Merge pull request #2087 from poettering/dnssec

Basic DNSSEC support, and unrelated fixes

19 files changed, 1242 insertions, 154 deletions

diff --git a/Makefile.am b/Makefile.am
index cecd139e4f..29c7f322ea 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -5136,12 +5136,13 @@ polkitpolicy_in_files += \
 	src/import/org.freedesktop.import1.policy.in
 
 EXTRA_DIST += \
-	units/systemd-importd.service.in \
-	src/resolve/resolved.conf.in
+	units/systemd-importd.service.in
 
 
 # ------------------------------------------------------------------------------
 if ENABLE_RESOLVED
+if HAVE_GCRYPT
+
 systemd_resolved_SOURCES = \
 	src/resolve/resolved.c \
 	src/resolve/resolved-manager.c \
@@ -5181,6 +5182,8 @@ systemd_resolved_SOURCES = \
 	src/resolve/resolved-dns-zone.c \
 	src/resolve/resolved-dns-stream.h \
 	src/resolve/resolved-dns-stream.c \
+	src/resolve/resolved-dns-dnssec.h \
+	src/resolve/resolved-dns-dnssec.c \
 	src/resolve/dns-type.c \
 	src/resolve/dns-type.h
 
@@ -5226,9 +5229,6 @@ GENERAL_ALIASES += \
 nodist_pkgsysconf_DATA += \
 	src/resolve/resolved.conf
 
-tests += \
-	test-dns-domain
-
 libnss_resolve_la_SOURCES = \
 	src/nss-resolve/nss-resolve.sym \
 	src/nss-resolve/nss-resolve.c
@@ -5272,10 +5272,34 @@ systemd_resolve_host_LDADD = \
 rootlibexec_PROGRAMS += \
 	systemd-resolve-host
 
+tests += \
+	test-dns-domain \
+	test-dnssec
+
+test_dnssec_SOURCES = \
+	src/resolve/test-dnssec.c \
+	src/resolve/resolved-dns-packet.c \
+	src/resolve/resolved-dns-packet.h \
+	src/resolve/resolved-dns-rr.c \
+	src/resolve/resolved-dns-rr.h \
+	src/resolve/resolved-dns-answer.c \
+	src/resolve/resolved-dns-answer.h \
+	src/resolve/resolved-dns-question.c \
+	src/resolve/resolved-dns-question.h \
+	src/resolve/resolved-dns-dnssec.c \
+	src/resolve/resolved-dns-dnssec.h \
+	src/resolve/dns-type.c \
+	src/resolve/dns-type.h
+
+test_dnssec_LDADD = \
+	libshared.la
+
+endif
 endif
 
 EXTRA_DIST += \
-	units/systemd-resolved.service.m4.in
+	units/systemd-resolved.service.m4.in \
+	src/resolve/resolved.conf.in
 
 # ------------------------------------------------------------------------------
 if ENABLE_NETWORKD
diff --git a/src/hostname/hostnamed.c b/src/hostname/hostnamed.c
index e1fbacd11b..d383041d39 100644
--- a/src/hostname/hostnamed.c
+++ b/src/hostname/hostnamed.c
@@ -212,10 +212,10 @@ try_dmi:
            unreliable enough, so let's not do any additional guesswork
            on top of that.
 
-           See the SMBIOS Specification 2.7.1 section 7.4.1 for
+           See the SMBIOS Specification 4.0 section 7.4.1 for
            details about the values listed here:
 
-           http://www.dmtf.org/sites/default/files/standards/documents/DSP0134_2.7.1.pdf
+           https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.0.0.pdf
          */
 
         switch (t) {
@@ -237,7 +237,11 @@ try_dmi:
 
         case 0x11:
         case 0x1C:
+        case 0x1D:
                 return "server";
+
+        case 0x1E:
+                return "tablet";
         }
 
         return NULL;
diff --git a/src/libsystemd-network/sd-dhcp-client.c b/src/libsystemd-network/sd-dhcp-client.c
index a03c8460a8..4521f8f0b1 100644
--- a/src/libsystemd-network/sd-dhcp-client.c
+++ b/src/libsystemd-network/sd-dhcp-client.c
@@ -554,7 +554,7 @@ static int client_append_fqdn_option(DHCPMessage *message, size_t optlen, size_t
         buffer[1] = 0;                 /* RCODE1 (deprecated) */
         buffer[2] = 0;                 /* RCODE2 (deprecated) */
 
-        r = dns_name_to_wire_format(fqdn, buffer + 3, sizeof(buffer) - 3);
+        r = dns_name_to_wire_format(fqdn, buffer + 3, sizeof(buffer) - 3, false);
         if (r > 0)
                 r = dhcp_option_append(message, optlen, optoffset, 0,
                                        DHCP_OPTION_FQDN, 3 + r, buffer);
diff --git a/src/resolve/resolved-bus.c b/src/resolve/resolved-bus.c
index f86c4ceb05..ddde3af0c3 100644
--- a/src/resolve/resolved-bus.c
+++ b/src/resolve/resolved-bus.c
@@ -425,8 +425,6 @@ fail:
 }
 
 static int bus_message_append_rr(sd_bus_message *m, DnsResourceRecord *rr, int ifindex) {
-        _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
-        size_t start;
         int r;
 
         assert(m);
@@ -443,17 +441,11 @@ static int bus_message_append_rr(sd_bus_message *m, DnsResourceRecord *rr, int i
         if (r < 0)
                 return r;
 
-        r = dns_packet_new(&p, DNS_PROTOCOL_DNS, 0);
+        r = dns_resource_record_to_wire_format(rr, false);
         if (r < 0)
                 return r;
 
-        p->refuse_compression = true;
-
-        r = dns_packet_append_rr(p, rr, &start);
-        if (r < 0)
-                return r;
-
-        r = sd_bus_message_append_array(m, 'y', DNS_PACKET_DATA(p) + start, p->size - start);
+        r = sd_bus_message_append_array(m, 'y', rr->wire_format, rr->wire_format_size);
         if (r < 0)
                 return r;
 
diff --git a/src/resolve/resolved-dns-answer.h b/src/resolve/resolved-dns-answer.h
index 8814919deb..89c254b02e 100644
--- a/src/resolve/resolved-dns-answer.h
+++ b/src/resolve/resolved-dns-answer.h
@@ -24,6 +24,7 @@
 typedef struct DnsAnswer DnsAnswer;
 typedef struct DnsAnswerItem DnsAnswerItem;
 
+#include "macro.h"
 #include "resolved-dns-rr.h"
 
 /* A simple array of resource records. We keep track of the
@@ -59,19 +60,23 @@ int dns_answer_reserve(DnsAnswer **a, unsigned n_free);
 
 DEFINE_TRIVIAL_CLEANUP_FUNC(DnsAnswer*, dns_answer_unref);
 
-#define DNS_ANSWER_FOREACH(kk, a)                                       \
-        for (unsigned _i = ({                                           \
+#define _DNS_ANSWER_FOREACH(q, kk, a)                                   \
+        for (unsigned UNIQ_T(i, q) = ({                                 \
                                 (kk) = ((a) && (a)->n_rrs > 0) ? (a)->items[0].rr : NULL; \
                                 0;                                      \
-                           });                                          \
-             (a) && ((_i) < (a)->n_rrs);                                \
-             _i++, (kk) = (_i < (a)->n_rrs ? (a)->items[_i].rr : NULL))
+                        });                                             \
+             (a) && (UNIQ_T(i, q) < (a)->n_rrs);                        \
+             UNIQ_T(i, q)++, (kk) = (UNIQ_T(i, q) < (a)->n_rrs ? (a)->items[UNIQ_T(i, q)].rr : NULL))
 
-#define DNS_ANSWER_FOREACH_IFINDEX(kk, ifindex, a)                      \
-        for (unsigned _i = ({                                           \
+#define DNS_ANSWER_FOREACH(kk, a) _DNS_ANSWER_FOREACH(UNIQ, kk, a)
+
+#define _DNS_ANSWER_FOREACH_IFINDEX(q, kk, ifindex, a)                  \
+        for (unsigned UNIQ_T(i, q) = ({                                 \
                                 (kk) = ((a) && (a)->n_rrs > 0) ? (a)->items[0].rr : NULL; \
                                 (ifindex) = ((a) && (a)->n_rrs > 0) ? (a)->items[0].ifindex : 0; \
                                 0;                                      \
-                           });                                          \
-             (a) && ((_i) < (a)->n_rrs);                                \
-             _i++, (kk) = ((_i < (a)->n_rrs) ? (a)->items[_i].rr : NULL), (ifindex) = ((_i < (a)->n_rrs) ? (a)->items[_i].ifindex : 0))
+                        });                                             \
+             (a) && (UNIQ_T(i, q) < (a)->n_rrs);                        \
+             UNIQ_T(i, q)++, (kk) = ((UNIQ_T(i, q) < (a)->n_rrs) ? (a)->items[UNIQ_T(i, q)].rr : NULL), (ifindex) = ((UNIQ_T(i, q) < (a)->n_rrs) ? (a)->items[UNIQ_T(i, q)].ifindex : 0))
+
+#define DNS_ANSWER_FOREACH_IFINDEX(kk, ifindex, a) _DNS_ANSWER_FOREACH_IFINDEX(UNIQ, kk, ifindex, a)
diff --git a/src/resolve/resolved-dns-cache.c b/src/resolve/resolved-dns-cache.c
index d963ce6e00..3f34017789 100644
--- a/src/resolve/resolved-dns-cache.c
+++ b/src/resolve/resolved-dns-cache.c
@@ -521,8 +521,8 @@ fail:
         return r;
 }
 
-static DnsCacheItem *dns_cache_get_by_key_follow_cname(DnsCache *c, DnsResourceKey *k) {
-        _cleanup_(dns_resource_key_unrefp) DnsResourceKey *cname_key = NULL;
+static DnsCacheItem *dns_cache_get_by_key_follow_cname_dname_nsec(DnsCache *c, DnsResourceKey *k) {
+        _cleanup_(dns_resource_key_unrefp) DnsResourceKey *nsec_key = NULL, *cname_key = NULL;
         DnsCacheItem *i;
         const char *n;
         int r;
@@ -534,20 +534,29 @@ static DnsCacheItem *dns_cache_get_by_key_follow_cname(DnsCache *c, DnsResourceK
          * much, after all this is just a cache */
 
         i = hashmap_get(c->by_key, k);
-        if (i || k->type == DNS_TYPE_CNAME || k->type == DNS_TYPE_DNAME)
+        if (i || IN_SET(k->type, DNS_TYPE_CNAME, DNS_TYPE_DNAME, DNS_TYPE_NSEC))
+                return i;
+
+        n = DNS_RESOURCE_KEY_NAME(k);
+
+        /* Check if we have an NSEC record instead for the name. */
+        nsec_key = dns_resource_key_new(k->class, DNS_TYPE_NSEC, n);
+        if (!nsec_key)
+                return NULL;
+
+        i = hashmap_get(c->by_key, nsec_key);
+        if (i)
                 return i;
 
         /* Check if we have a CNAME record instead */
         cname_key = dns_resource_key_new_cname(k);
         if (!cname_key)
                 return NULL;
-
         i = hashmap_get(c->by_key, cname_key);
         if (i)
                 return i;
 
         /* OK, let's look for cached DNAME records. */
-        n = DNS_RESOURCE_KEY_NAME(k);
         for (;;) {
                 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *dname_key = NULL;
                 char label[DNS_LABEL_MAX];
@@ -578,6 +587,7 @@ int dns_cache_lookup(DnsCache *c, DnsResourceKey *key, int *rcode, DnsAnswer **r
         int r;
         bool nxdomain = false;
         _cleanup_free_ char *key_str = NULL;
+        DnsResourceRecord *nsec = NULL;
         DnsCacheItem *j, *first;
 
         assert(c);
@@ -601,7 +611,7 @@ int dns_cache_lookup(DnsCache *c, DnsResourceKey *key, int *rcode, DnsAnswer **r
                 return 0;
         }
 
-        first = dns_cache_get_by_key_follow_cname(c, key);
+        first = dns_cache_get_by_key_follow_cname_dname_nsec(c, key);
         if (!first) {
                 /* If one question cannot be answered we need to refresh */
 
@@ -617,9 +627,11 @@ int dns_cache_lookup(DnsCache *c, DnsResourceKey *key, int *rcode, DnsAnswer **r
         }
 
         LIST_FOREACH(by_key, j, first) {
-                if (j->rr)
+                if (j->rr) {
+                        if (j->rr->key->type == DNS_TYPE_NSEC)
+                                nsec = j->rr;
                         n++;
-                else if (j->type == DNS_CACHE_NXDOMAIN)
+                } else if (j->type == DNS_CACHE_NXDOMAIN)
                         nxdomain = true;
         }
 
@@ -627,9 +639,22 @@ int dns_cache_lookup(DnsCache *c, DnsResourceKey *key, int *rcode, DnsAnswer **r
         if (r < 0)
                 return r;
 
+        if (nsec && key->type != DNS_TYPE_NSEC) {
+                log_debug("NSEC NODATA cache hit for %s", key_str);
+
+                /* We only found an NSEC record that matches our name.
+                 * If it says the type doesn't exit report
+                 * NODATA. Otherwise report a cache miss. */
+
+                *ret = NULL;
+                *rcode = DNS_RCODE_SUCCESS;
+
+                return !bitmap_isset(nsec->nsec.types, key->type);
+        }
+
         log_debug("%s cache hit for %s",
-                  nxdomain ? "NXDOMAIN" :
-                     n > 0 ? "Positive" : "NODATA",
+                  n > 0    ? "Positive" :
+                  nxdomain ? "NXDOMAIN" : "NODATA",
                   key_str);
 
         if (n <= 0) {
diff --git a/src/resolve/resolved-dns-cache.h b/src/resolve/resolved-dns-cache.h
index 164435b4fb..561d31ad99 100644
--- a/src/resolve/resolved-dns-cache.h
+++ b/src/resolve/resolved-dns-cache.h
@@ -21,7 +21,6 @@
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 ***/
 
-
 #include "hashmap.h"
 #include "list.h"
 #include "prioq.h"
diff --git a/src/resolve/resolved-dns-dnssec.c b/src/resolve/resolved-dns-dnssec.c
new file mode 100644
index 0000000000..a32e938045
--- /dev/null
+++ b/src/resolve/resolved-dns-dnssec.c
@@ -0,0 +1,692 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2015 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <gcrypt.h>
+
+#include "alloc-util.h"
+#include "dns-domain.h"
+#include "resolved-dns-dnssec.h"
+#include "resolved-dns-packet.h"
+
+/* Open question:
+ *
+ * How does the DNSSEC canonical form of a hostname with a label
+ * containing a dot look like, the way DNS-SD does it?
+ *
+ * */
+
+#define VERIFY_RRS_MAX 256
+#define MAX_KEY_SIZE (32*1024)
+
+/*
+ * The DNSSEC Chain of trust:
+ *
+ *            Normal RRs are protected via RRSIG RRs in combination with DNSKEY RRs, all in the same zone
+ *            DNSKEY RRs are either protected like normal RRs, or via a DS from a zone "higher" up the tree
+ *            DS RRs are protected like normal RRs
+ *
+ * Example chain:
+ *            Normal RR → RRSIG/DNSKEY+ → DS → RRSIG/DNSKEY+ → DS → ... → DS → RRSIG/DNSKEY+ → DS
+ */
+
+static bool dnssec_algorithm_supported(int algorithm) {
+        return IN_SET(algorithm,
+                      DNSSEC_ALGORITHM_RSASHA1,
+                      DNSSEC_ALGORITHM_RSASHA1_NSEC3_SHA1,
+                      DNSSEC_ALGORITHM_RSASHA256,
+                      DNSSEC_ALGORITHM_RSASHA512);
+}
+
+static bool dnssec_digest_supported(int digest) {
+        return IN_SET(digest,
+                      DNSSEC_DIGEST_SHA1,
+                      DNSSEC_DIGEST_SHA256);
+}
+
+uint16_t dnssec_keytag(DnsResourceRecord *dnskey) {
+        const uint8_t *p;
+        uint32_t sum;
+        size_t i;
+
+        /* The algorithm from RFC 4034, Appendix B. */
+
+        assert(dnskey);
+        assert(dnskey->key->type == DNS_TYPE_DNSKEY);
+
+        sum = (uint32_t) dnskey->dnskey.flags +
+                ((((uint32_t) dnskey->dnskey.protocol) << 8) + (uint32_t) dnskey->dnskey.algorithm);
+
+        p = dnskey->dnskey.key;
+
+        for (i = 0; i < dnskey->dnskey.key_size; i++)
+                sum += (i & 1) == 0 ? (uint32_t) p[i] << 8 : (uint32_t) p[i];
+
+        sum += (sum >> 16) & UINT32_C(0xFFFF);
+
+        return sum & UINT32_C(0xFFFF);
+}
+
+static int rr_compare(const void *a, const void *b) {
+        DnsResourceRecord **x = (DnsResourceRecord**) a, **y = (DnsResourceRecord**) b;
+        size_t m;
+        int r;
+
+        /* Let's order the RRs according to RFC 4034, Section 6.3 */
+
+        assert(x);
+        assert(*x);
+        assert((*x)->wire_format);
+        assert(y);
+        assert(*y);
+        assert((*y)->wire_format);
+
+        m = MIN((*x)->wire_format_size, (*y)->wire_format_size);
+
+        r = memcmp((*x)->wire_format, (*y)->wire_format, m);
+        if (r != 0)
+                return r;
+
+        if ((*x)->wire_format_size < (*y)->wire_format_size)
+                return -1;
+        else if ((*x)->wire_format_size > (*y)->wire_format_size)
+                return 1;
+
+        return 0;
+}
+
+static int dnssec_rsa_verify(
+                const char *hash_algorithm,
+                const void *signature, size_t signature_size,
+                const void *data, size_t data_size,
+                const void *exponent, size_t exponent_size,
+                const void *modulus, size_t modulus_size) {
+
+        gcry_sexp_t public_key_sexp = NULL, data_sexp = NULL, signature_sexp = NULL;
+        gcry_mpi_t n = NULL, e = NULL, s = NULL;
+        gcry_error_t ge;
+        int r;
+
+        assert(hash_algorithm);
+
+        ge = gcry_mpi_scan(&s, GCRYMPI_FMT_USG, signature, signature_size, NULL);
+        if (ge != 0) {
+                r = -EIO;
+                goto finish;
+        }
+
+        ge = gcry_mpi_scan(&e, GCRYMPI_FMT_USG, exponent, exponent_size, NULL);
+        if (ge != 0) {
+                r = -EIO;
+                goto finish;
+        }
+
+        ge = gcry_mpi_scan(&n, GCRYMPI_FMT_USG, modulus, modulus_size, NULL);
+        if (ge != 0) {
+                r = -EIO;
+                goto finish;
+        }
+
+        ge = gcry_sexp_build(&signature_sexp,
+                             NULL,
+                             "(sig-val (rsa (s %m)))",
+                             s);
+
+        if (ge != 0) {
+                r = -EIO;
+                goto finish;
+        }
+
+        ge = gcry_sexp_build(&data_sexp,
+                             NULL,
+                             "(data (flags pkcs1) (hash %s %b))",
+                             hash_algorithm,
+                             (int) data_size,
+                             data);
+        if (ge != 0) {
+                r = -EIO;
+                goto finish;
+        }
+
+        ge = gcry_sexp_build(&public_key_sexp,
+                             NULL,
+                             "(public-key (rsa (n %m) (e %m)))",
+                             n,
+                             e);
+        if (ge != 0) {
+                r = -EIO;
+                goto finish;
+        }
+
+        ge = gcry_pk_verify(signature_sexp, data_sexp, public_key_sexp);
+        if (ge == GPG_ERR_BAD_SIGNATURE)
+                r = 0;
+        else if (ge != 0)
+                r = -EIO;
+        else
+                r = 1;
+
+finish:
+        if (e)
+                gcry_mpi_release(e);
+        if (n)
+                gcry_mpi_release(n);
+        if (s)
+                gcry_mpi_release(s);
+
+        if (public_key_sexp)
+                gcry_sexp_release(public_key_sexp);
+        if (signature_sexp)
+                gcry_sexp_release(signature_sexp);
+        if (data_sexp)
+                gcry_sexp_release(data_sexp);
+
+        return r;
+}
+
+static void md_add_uint8(gcry_md_hd_t md, uint8_t v) {
+        gcry_md_write(md, &v, sizeof(v));
+}
+
+static void md_add_uint16(gcry_md_hd_t md, uint16_t v) {
+        v = htobe16(v);
+        gcry_md_write(md, &v, sizeof(v));
+}
+
+static void md_add_uint32(gcry_md_hd_t md, uint32_t v) {
+        v = htobe32(v);
+        gcry_md_write(md, &v, sizeof(v));
+}
+
+static int dnssec_rrsig_expired(DnsResourceRecord *rrsig, usec_t realtime) {
+        usec_t expiration, inception, skew;
+
+        assert(rrsig);
+        assert(rrsig->key->type == DNS_TYPE_RRSIG);
+
+        if (realtime == USEC_INFINITY)
+                realtime = now(CLOCK_REALTIME);
+
+        expiration = rrsig->rrsig.expiration * USEC_PER_SEC;
+        inception = rrsig->rrsig.inception * USEC_PER_SEC;
+
+        if (inception > expiration)
+                return -EINVAL;
+
+        /* Permit a certain amount of clock skew of 10% of the valid time range */
+        skew = (expiration - inception) / 10;
+
+        if (inception < skew)
+                inception = 0;
+        else
+                inception -= skew;
+
+        if (expiration + skew < expiration)
+                expiration = USEC_INFINITY;
+        else
+                expiration += skew;
+
+        return realtime < inception || realtime > expiration;
+}
+
+int dnssec_verify_rrset(
+                DnsAnswer *a,
+                DnsResourceKey *key,
+                DnsResourceRecord *rrsig,
+                DnsResourceRecord *dnskey,
+                usec_t realtime) {
+
+        uint8_t wire_format_name[DNS_WIRE_FOMAT_HOSTNAME_MAX];
+        size_t exponent_size, modulus_size, hash_size;
+        void *exponent, *modulus, *hash;
+        DnsResourceRecord **list, *rr;
+        gcry_md_hd_t md = NULL;
+        size_t k, n = 0;
+        int r;
+
+        assert(key);
+        assert(rrsig);
+        assert(dnskey);
+        assert(rrsig->key->type == DNS_TYPE_RRSIG);
+        assert(dnskey->key->type == DNS_TYPE_DNSKEY);
+
+        /* Verifies the the RRSet matching the specified "key" in "a",
+         * using the signature "rrsig" and the key "dnskey". It's
+         * assumed the RRSIG and DNSKEY match. */
+
+        if (!dnssec_algorithm_supported(rrsig->rrsig.algorithm))
+                return -EOPNOTSUPP;
+
+        if (a->n_rrs > VERIFY_RRS_MAX)
+                return -E2BIG;
+
+        r = dnssec_rrsig_expired(rrsig, realtime);
+        if (r < 0)
+                return r;
+        if (r > 0)
+                return DNSSEC_SIGNATURE_EXPIRED;
+
+        /* Collect all relevant RRs in a single array, so that we can look at the RRset */
+        list = newa(DnsResourceRecord *, a->n_rrs);
+
+        DNS_ANSWER_FOREACH(rr, a) {
+                r = dns_resource_key_equal(key, rr->key);
+                if (r < 0)
+                        return r;
+                if (r == 0)
+                        continue;
+
+                /* We need the wire format for ordering, and digest calculation */
+                r = dns_resource_record_to_wire_format(rr, true);
+                if (r < 0)
+                        return r;
+
+                list[n++] = rr;
+        }
+
+        if (n <= 0)
+                return -ENODATA;
+
+        /* Bring the RRs into canonical order */
+        qsort_safe(list, n, sizeof(DnsResourceRecord), rr_compare);
+
+        /* OK, the RRs are now in canonical order. Let's calculate the digest */
+        switch (rrsig->rrsig.algorithm) {
+
+        case DNSSEC_ALGORITHM_RSASHA1:
+        case DNSSEC_ALGORITHM_RSASHA1_NSEC3_SHA1:
+                gcry_md_open(&md, GCRY_MD_SHA1, 0);
+                hash_size = 20;
+                break;
+
+        case DNSSEC_ALGORITHM_RSASHA256:
+                gcry_md_open(&md, GCRY_MD_SHA256, 0);
+                hash_size = 32;
+                break;
+
+        case DNSSEC_ALGORITHM_RSASHA512:
+                gcry_md_open(&md, GCRY_MD_SHA512, 0);
+                hash_size = 64;
+                break;
+
+        default:
+                assert_not_reached("Unknown digest");
+        }
+
+        if (!md)
+                return -EIO;
+
+        md_add_uint16(md, rrsig->rrsig.type_covered);
+        md_add_uint8(md, rrsig->rrsig.algorithm);
+        md_add_uint8(md, rrsig->rrsig.labels);
+        md_add_uint32(md, rrsig->rrsig.original_ttl);
+        md_add_uint32(md, rrsig->rrsig.expiration);
+        md_add_uint32(md, rrsig->rrsig.inception);
+        md_add_uint16(md, rrsig->rrsig.key_tag);
+
+        r = dns_name_to_wire_format(rrsig->rrsig.signer, wire_format_name, sizeof(wire_format_name), true);
+        if (r < 0)
+                goto finish;
+        gcry_md_write(md, wire_format_name, r);
+
+        for (k = 0; k < n; k++) {
+                size_t l;
+                rr = list[k];
+
+                r = dns_name_to_wire_format(DNS_RESOURCE_KEY_NAME(rr->key), wire_format_name, sizeof(wire_format_name), true);
+                if (r < 0)
+                        goto finish;
+                gcry_md_write(md, wire_format_name, r);
+
+                md_add_uint16(md, rr->key->type);
+                md_add_uint16(md, rr->key->class);
+                md_add_uint32(md, rrsig->rrsig.original_ttl);
+
+                assert(rr->wire_format_rdata_offset <= rr->wire_format_size);
+                l = rr->wire_format_size - rr->wire_format_rdata_offset;
+                assert(l <= 0xFFFF);
+
+                md_add_uint16(md, (uint16_t) l);
+                gcry_md_write(md, (uint8_t*) rr->wire_format + rr->wire_format_rdata_offset, l);
+        }
+
+        hash = gcry_md_read(md, 0);
+        if (!hash) {
+                r = -EIO;
+                goto finish;
+        }
+
+        if (*(uint8_t*) dnskey->dnskey.key == 0) {
+                /* exponent is > 255 bytes long */
+
+                exponent = (uint8_t*) dnskey->dnskey.key + 3;
+                exponent_size =
+                        ((size_t) (((uint8_t*) dnskey->dnskey.key)[0]) << 8) |
+                        ((size_t) ((uint8_t*) dnskey->dnskey.key)[1]);
+
+                if (exponent_size < 256) {
+                        r = -EINVAL;
+                        goto finish;
+                }
+
+                if (3 + exponent_size >= dnskey->dnskey.key_size) {
+                        r = -EINVAL;
+                        goto finish;
+                }
+
+                modulus = (uint8_t*) dnskey->dnskey.key + 3 + exponent_size;
+                modulus_size = dnskey->dnskey.key_size - 3 - exponent_size;
+
+        } else {
+                /* exponent is <= 255 bytes long */
+
+                exponent = (uint8_t*) dnskey->dnskey.key + 1;
+                exponent_size = (size_t) ((uint8_t*) dnskey->dnskey.key)[0];
+
+                if (exponent_size <= 0) {
+                        r = -EINVAL;
+                        goto finish;
+                }
+
+                if (1 + exponent_size >= dnskey->dnskey.key_size) {
+                        r = -EINVAL;
+                        goto finish;
+                }
+
+                modulus = (uint8_t*) dnskey->dnskey.key + 1 + exponent_size;
+                modulus_size = dnskey->dnskey.key_size - 1 - exponent_size;
+        }
+
+        r = dnssec_rsa_verify(
+                        gcry_md_algo_name(gcry_md_get_algo(md)),
+                        rrsig->rrsig.signature, rrsig->rrsig.signature_size,
+                        hash, hash_size,
+                        exponent, exponent_size,
+                        modulus, modulus_size);
+        if (r < 0)
+                goto finish;
+
+        r = r ? DNSSEC_VERIFIED : DNSSEC_INVALID;
+
+finish:
+        gcry_md_close(md);
+        return r;
+}
+
+int dnssec_rrsig_match_dnskey(DnsResourceRecord *rrsig, DnsResourceRecord *dnskey) {
+
+        assert(rrsig);
+        assert(dnskey);
+
+        /* Checks if the specified DNSKEY RR matches the key used for
+         * the signature in the specified RRSIG RR */
+
+        if (rrsig->key->type != DNS_TYPE_RRSIG)
+                return -EINVAL;
+
+        if (dnskey->key->type != DNS_TYPE_DNSKEY)
+                return 0;
+        if (dnskey->key->class != rrsig->key->class)
+                return 0;
+        if ((dnskey->dnskey.flags & DNSKEY_FLAG_ZONE_KEY) == 0)
+                return 0;
+        if (dnskey->dnskey.protocol != 3)
+                return 0;
+        if (dnskey->dnskey.algorithm != rrsig->rrsig.algorithm)
+                return 0;
+
+        if (dnssec_keytag(dnskey) != rrsig->rrsig.key_tag)
+                return 0;
+
+        return dns_name_equal(DNS_RESOURCE_KEY_NAME(dnskey->key), DNS_RESOURCE_KEY_NAME(rrsig->key));
+}
+
+int dnssec_key_match_rrsig(DnsResourceKey *key, DnsResourceRecord *rrsig) {
+        assert(key);
+        assert(rrsig);
+
+        /* Checks if the specified RRSIG RR protects the RRSet of the specified RR key. */
+
+        if (rrsig->key->type != DNS_TYPE_RRSIG)
+                return 0;
+        if (rrsig->key->class != key->class)
+                return 0;
+        if (rrsig->rrsig.type_covered != key->type)
+                return 0;
+
+        return dns_name_equal(DNS_RESOURCE_KEY_NAME(rrsig->key), DNS_RESOURCE_KEY_NAME(key));
+}
+
+int dnssec_verify_rrset_search(
+                DnsAnswer *a,
+                DnsResourceKey *key,
+                DnsAnswer *validated_dnskeys,
+                usec_t realtime) {
+
+        bool found_rrsig = false, found_dnskey = false;
+        DnsResourceRecord *rrsig;
+        int r;
+
+        assert(key);
+
+        /* Verifies all RRs from "a" that match the key "key", against DNSKEY RRs in "validated_dnskeys" */
+
+        if (!a || a->n_rrs <= 0)
+                return -ENODATA;
+
+        /* Iterate through each RRSIG RR. */
+        DNS_ANSWER_FOREACH(rrsig, a) {
+                DnsResourceRecord *dnskey;
+
+                r = dnssec_key_match_rrsig(key, rrsig);
+                if (r < 0)
+                        return r;
+                if (r == 0)
+                        continue;
+
+                found_rrsig = true;
+
+                DNS_ANSWER_FOREACH(dnskey, validated_dnskeys) {
+
+                        r = dnssec_rrsig_match_dnskey(rrsig, dnskey);
+                        if (r < 0)
+                                return r;
+                        if (r == 0)
+                                continue;
+
+                        found_dnskey = true;
+
+                        /* Take the time here, if it isn't set yet, so
+                         * that we do all validations with the same
+                         * time. */
+                        if (realtime == USEC_INFINITY)
+                                realtime = now(CLOCK_REALTIME);
+
+                        /* Yay, we found a matching RRSIG with a matching
+                         * DNSKEY, awesome. Now let's verify all entries of
+                         * the RRSet against the RRSIG and DNSKEY
+                         * combination. */
+
+                        r = dnssec_verify_rrset(a, key, rrsig, dnskey, realtime);
+                        if (r < 0 && r != EOPNOTSUPP)
+                                return r;
+                        if (r == DNSSEC_VERIFIED)
+                                return DNSSEC_VERIFIED;
+
+                        /* If the signature is invalid, or done using
+                           an unsupported algorithm, let's try another
+                           key and/or signature. After all they
+                           key_tags and stuff are not unique, and
+                           might be shared by multiple keys. */
+                }
+        }
+
+        if (found_dnskey)
+                return DNSSEC_INVALID;
+
+        if (found_rrsig)
+                return DNSSEC_MISSING_KEY;
+
+        return DNSSEC_NO_SIGNATURE;
+}
+
+int dnssec_canonicalize(const char *n, char *buffer, size_t buffer_max) {
+        _cleanup_free_ char *s = NULL;
+        size_t c = 0;
+        int r;
+
+        /* Converts the specified hostname into DNSSEC canonicalized
+         * form. */
+
+        if (buffer_max < 2)
+                return -ENOBUFS;
+
+        for (;;) {
+                size_t i;
+
+                r = dns_label_unescape(&n, buffer, buffer_max);
+                if (r < 0)
+                        return r;
+                if (r == 0)
+                        break;
+                if (r > 0) {
+                        int k;
+
+                        /* DNSSEC validation is always done on the ASCII version of the label */
+                        k = dns_label_apply_idna(buffer, r, buffer, buffer_max);
+                        if (k < 0)
+                                return k;
+                        if (k > 0)
+                                r = k;
+                }
+
+                if (buffer_max < (size_t) r + 2)
+                        return -ENOBUFS;
+
+                /* The DNSSEC canonical form is not clear on what to
+                 * do with dots appearing in labels, the way DNS-SD
+                 * does it. Refuse it for now. */
+
+                if (memchr(buffer, '.', r))
+                        return -EINVAL;
+
+                for (i = 0; i < (size_t) r; i ++) {
+                        if (buffer[i] >= 'A' && buffer[i] <= 'Z')
+                                buffer[i] = buffer[i] - 'A' + 'a';
+                }
+
+                buffer[r] = '.';
+
+                buffer += r + 1;
+                c += r + 1;
+
+                buffer_max -= r + 1;
+        }
+
+        if (c <= 0) {
+                /* Not even a single label: this is the root domain name */
+
+                assert(buffer_max > 2);
+                buffer[0] = '.';
+                buffer[1] = 0;
+
+                return 1;
+        }
+
+        return (int) c;
+}
+
+int dnssec_verify_dnskey(DnsResourceRecord *dnskey, DnsResourceRecord *ds) {
+        gcry_md_hd_t md = NULL;
+        char owner_name[DNSSEC_CANONICAL_HOSTNAME_MAX];
+        void *result;
+        int r;
+
+        assert(dnskey);
+        assert(ds);
+
+        /* Implements DNSKEY verification by a DS, according to RFC 4035, section 5.2 */
+
+        if (dnskey->key->type != DNS_TYPE_DNSKEY)
+                return -EINVAL;
+        if (ds->key->type != DNS_TYPE_DS)
+                return -EINVAL;
+        if ((dnskey->dnskey.flags & DNSKEY_FLAG_ZONE_KEY) == 0)
+                return -EKEYREJECTED;
+        if (dnskey->dnskey.protocol != 3)
+                return -EKEYREJECTED;
+
+        if (!dnssec_algorithm_supported(dnskey->dnskey.algorithm))
+                return -EOPNOTSUPP;
+        if (!dnssec_digest_supported(ds->ds.digest_type))
+                return -EOPNOTSUPP;
+
+        if (dnskey->dnskey.algorithm != ds->ds.algorithm)
+                return 0;
+        if (dnssec_keytag(dnskey) != ds->ds.key_tag)
+                return 0;
+
+        switch (ds->ds.digest_type) {
+
+        case DNSSEC_DIGEST_SHA1:
+
+                if (ds->ds.digest_size != 20)
+                        return 0;
+
+                gcry_md_open(&md, GCRY_MD_SHA1, 0);
+                break;
+
+        case DNSSEC_DIGEST_SHA256:
+
+                if (ds->ds.digest_size != 32)
+                        return 0;
+
+                gcry_md_open(&md, GCRY_MD_SHA256, 0);
+                break;
+
+        default:
+                assert_not_reached("Unknown digest");
+        }
+
+        if (!md)
+                return -EIO;
+
+        r = dnssec_canonicalize(DNS_RESOURCE_KEY_NAME(dnskey->key), owner_name, sizeof(owner_name));
+        if (r < 0)
+                goto finish;
+
+        gcry_md_write(md, owner_name, r);
+        md_add_uint16(md, dnskey->dnskey.flags);
+        md_add_uint8(md, dnskey->dnskey.protocol);
+        md_add_uint8(md, dnskey->dnskey.algorithm);
+        gcry_md_write(md, dnskey->dnskey.key, dnskey->dnskey.key_size);
+
+        result = gcry_md_read(md, 0);
+        if (!result) {
+                r = -EIO;
+                goto finish;
+        }
+
+        r = memcmp(result, ds->ds.digest, ds->ds.digest_size) != 0;
+
+finish:
+        gcry_md_close(md);
+        return r;
+}
diff --git a/src/resolve/resolved-dns-dnssec.h b/src/resolve/resolved-dns-dnssec.h
new file mode 100644
index 0000000000..8f812bc1fb
--- /dev/null
+++ b/src/resolve/resolved-dns-dnssec.h
@@ -0,0 +1,49 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+#pragma once
+
+/***
+  This file is part of systemd.
+
+  Copyright 2015 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include "dns-domain.h"
+#include "resolved-dns-answer.h"
+#include "resolved-dns-rr.h"
+
+enum {
+        DNSSEC_VERIFIED,
+        DNSSEC_INVALID,
+        DNSSEC_NO_SIGNATURE,
+        DNSSEC_MISSING_KEY,
+        DNSSEC_SIGNATURE_EXPIRED,
+};
+
+
+#define DNSSEC_CANONICAL_HOSTNAME_MAX (DNS_HOSTNAME_MAX + 2)
+
+int dnssec_rrsig_match_dnskey(DnsResourceRecord *rrsig, DnsResourceRecord *dnskey);
+int dnssec_key_match_rrsig(DnsResourceKey *key, DnsResourceRecord *rrsig);
+
+int dnssec_verify_rrset(DnsAnswer *answer, DnsResourceKey *key, DnsResourceRecord *rrsig, DnsResourceRecord *dnskey, usec_t realtime);
+int dnssec_verify_rrset_search(DnsAnswer *a, DnsResourceKey *key, DnsAnswer *validated_dnskeys, usec_t realtime);
+
+int dnssec_verify_dnskey(DnsResourceRecord *dnskey, DnsResourceRecord *ds);
+
+uint16_t dnssec_keytag(DnsResourceRecord *dnskey);
+
+int dnssec_canonicalize(const char *n, char *buffer, size_t buffer_max);
diff --git a/src/resolve/resolved-dns-packet.c b/src/resolve/resolved-dns-packet.c
index 75ca23fd08..2a010ef507 100644
--- a/src/resolve/resolved-dns-packet.c
+++ b/src/resolve/resolved-dns-packet.c
@@ -108,6 +108,8 @@ DnsPacket *dns_packet_ref(DnsPacket *p) {
         if (!p)
                 return NULL;
 
+        assert(!p->on_stack);
+
         assert(p->n_ref > 0);
         p->n_ref++;
         return p;
@@ -126,7 +128,9 @@ static void dns_packet_free(DnsPacket *p) {
         hashmap_free(p->names);
 
         free(p->_data);
-        free(p);
+
+        if (!p->on_stack)
+                free(p);
 }
 
 DnsPacket *dns_packet_unref(DnsPacket *p) {
@@ -351,25 +355,10 @@ int dns_packet_append_uint32(DnsPacket *p, uint32_t v, size_t *start) {
 }
 
 int dns_packet_append_string(DnsPacket *p, const char *s, size_t *start) {
-        void *d;
-        size_t l;
-        int r;
-
         assert(p);
         assert(s);
 
-        l = strlen(s);
-        if (l > 255)
-                return -E2BIG;
-
-        r = dns_packet_extend(p, 1 + l, &d, start);
-        if (r < 0)
-                return r;
-
-        ((uint8_t*) d)[0] = (uint8_t) l;
-        memcpy(((uint8_t*) d) + 1, s, l);
-
-        return 0;
+        return dns_packet_append_raw_string(p, s, strlen(s), start);
 }
 
 int dns_packet_append_raw_string(DnsPacket *p, const void *s, size_t size, size_t *start) {
@@ -395,7 +384,7 @@ int dns_packet_append_raw_string(DnsPacket *p, const void *s, size_t size, size_
 }
 
 int dns_packet_append_label(DnsPacket *p, const char *d, size_t l, size_t *start) {
-        void *w;
+        uint8_t *w;
         int r;
 
         assert(p);
@@ -404,12 +393,29 @@ int dns_packet_append_label(DnsPacket *p, const char *d, size_t l, size_t *start
         if (l > DNS_LABEL_MAX)
                 return -E2BIG;
 
-        r = dns_packet_extend(p, 1 + l, &w, start);
+        r = dns_packet_extend(p, 1 + l, (void**) &w, start);
         if (r < 0)
                 return r;
 
-        ((uint8_t*) w)[0] = (uint8_t) l;
-        memcpy(((uint8_t*) w) + 1, d, l);
+        *(w++) = (uint8_t) l;
+
+        if (p->canonical_form) {
+                size_t i;
+
+                /* Generate in canonical form, as defined by DNSSEC
+                 * RFC 4034, Section 6.2, i.e. all lower-case. */
+
+                for (i = 0; i < l; i++) {
+                        if (d[i] >= 'A' && d[i] <= 'Z')
+                                w[i] = (uint8_t) (d[i] - 'A' + 'a');
+                        else
+                                w[i] = (uint8_t) d[i];
+                }
+        } else
+                /* Otherwise, just copy the string unaltered. This is
+                 * essential for DNS-SD, where the casing of labels
+                 * matters and needs to be retained. */
+                memcpy(w, d, l);
 
         return 0;
 }
@@ -662,8 +668,8 @@ fail:
         return r;
 }
 
-int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *start) {
-        size_t saved_size, rdlength_offset, end, rdlength;
+int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *start, size_t *rdata_start) {
+        size_t saved_size, rdlength_offset, end, rdlength, rds;
         int r;
 
         assert(p);
@@ -684,6 +690,8 @@ int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *star
         if (r < 0)
                 goto fail;
 
+        rds = p->size - saved_size;
+
         switch (rr->unparseable ? _DNS_TYPE_INVALID : rr->key->type) {
 
         case DNS_TYPE_SRV:
@@ -841,11 +849,11 @@ int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *star
                 break;
 
         case DNS_TYPE_DNSKEY:
-                r = dns_packet_append_uint16(p, dnskey_to_flags(rr), NULL);
+                r = dns_packet_append_uint16(p, rr->dnskey.flags, NULL);
                 if (r < 0)
                         goto fail;
 
-                r = dns_packet_append_uint8(p, 3u, NULL);
+                r = dns_packet_append_uint8(p, rr->dnskey.protocol, NULL);
                 if (r < 0)
                         goto fail;
 
@@ -962,6 +970,9 @@ int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *star
         if (start)
                 *start = saved_size;
 
+        if (rdata_start)
+                *rdata_start = rds;
+
         return 0;
 
 fail:
@@ -1427,17 +1438,6 @@ static bool loc_size_ok(uint8_t size) {
         return m <= 9 && e <= 9 && (m > 0 || e == 0);
 }
 
-static int dnskey_parse_flags(DnsResourceRecord *rr, uint16_t flags) {
-        assert(rr);
-
-        if (flags & ~(DNSKEY_FLAG_SEP | DNSKEY_FLAG_ZONE_KEY))
-                return -EBADMSG;
-
-        rr->dnskey.zone_key_flag = flags & DNSKEY_FLAG_ZONE_KEY;
-        rr->dnskey.sep_flag = flags & DNSKEY_FLAG_SEP;
-        return 0;
-}
-
 int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
         _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
         _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
@@ -1706,28 +1706,15 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
 
                 break;
 
-        case DNS_TYPE_DNSKEY: {
-                uint16_t flags;
-                uint8_t proto;
-
-                r = dns_packet_read_uint16(p, &flags, NULL);
-                if (r < 0)
-                        goto fail;
-
-                r = dnskey_parse_flags(rr, flags);
+        case DNS_TYPE_DNSKEY:
+                r = dns_packet_read_uint16(p, &rr->dnskey.flags, NULL);
                 if (r < 0)
                         goto fail;
 
-                r = dns_packet_read_uint8(p, &proto, NULL);
+                r = dns_packet_read_uint8(p, &rr->dnskey.protocol, NULL);
                 if (r < 0)
                         goto fail;
 
-                /* protocol is required to be always 3 */
-                if (proto != 3) {
-                        r = -EBADMSG;
-                        goto fail;
-                }
-
                 r = dns_packet_read_uint8(p, &rr->dnskey.algorithm, NULL);
                 if (r < 0)
                         goto fail;
@@ -1744,7 +1731,6 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
                 }
 
                 break;
-        }
 
         case DNS_TYPE_RRSIG:
                 r = dns_packet_read_uint16(p, &rr->rrsig.type_covered, NULL);
@@ -1976,17 +1962,3 @@ static const char* const dns_protocol_table[_DNS_PROTOCOL_MAX] = {
         [DNS_PROTOCOL_LLMNR] = "llmnr",
 };
 DEFINE_STRING_TABLE_LOOKUP(dns_protocol, DnsProtocol);
-
-static const char* const dnssec_algorithm_table[_DNSSEC_ALGORITHM_MAX_DEFINED] = {
-        [DNSSEC_ALGORITHM_RSAMD5]             = "RSAMD5",
-        [DNSSEC_ALGORITHM_DH]                 = "DH",
-        [DNSSEC_ALGORITHM_DSA]                = "DSA",
-        [DNSSEC_ALGORITHM_ECC]                = "ECC",
-        [DNSSEC_ALGORITHM_RSASHA1]            = "RSASHA1",
-        [DNSSEC_ALGORITHM_DSA_NSEC3_SHA1]     = "DSA-NSEC3-SHA1",
-        [DNSSEC_ALGORITHM_RSASHA1_NSEC3_SHA1] = "RSASHA1-NSEC3-SHA1",
-        [DNSSEC_ALGORITHM_INDIRECT]           = "INDIRECT",
-        [DNSSEC_ALGORITHM_PRIVATEDNS]         = "PRIVATEDNS",
-        [DNSSEC_ALGORITHM_PRIVATEOID]         = "PRIVATEOID",
-};
-DEFINE_STRING_TABLE_LOOKUP(dnssec_algorithm, int);
diff --git a/src/resolve/resolved-dns-packet.h b/src/resolve/resolved-dns-packet.h
index 25dfb2642f..a6b88e6c79 100644
--- a/src/resolve/resolved-dns-packet.h
+++ b/src/resolve/resolved-dns-packet.h
@@ -88,8 +88,10 @@ struct DnsPacket {
         uint16_t sender_port, destination_port;
         uint32_t ttl;
 
-        bool extracted;
-        bool refuse_compression;
+        bool on_stack:1;
+        bool extracted:1;
+        bool refuse_compression:1;
+        bool canonical_form:1;
 };
 
 static inline uint8_t* DNS_PACKET_DATA(DnsPacket *p) {
@@ -162,7 +164,7 @@ int dns_packet_append_raw_string(DnsPacket *p, const void *s, size_t size, size_
 int dns_packet_append_label(DnsPacket *p, const char *s, size_t l, size_t *start);
 int dns_packet_append_name(DnsPacket *p, const char *name, bool allow_compression, size_t *start);
 int dns_packet_append_key(DnsPacket *p, const DnsResourceKey *key, size_t *start);
-int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *start);
+int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *start, size_t *rdata_start);
 int dns_packet_append_opt_rr(DnsPacket *p, uint16_t max_udp_size, bool edns0_do, size_t *start);
 
 void dns_packet_truncate(DnsPacket *p, size_t sz);
@@ -223,32 +225,6 @@ DnsProtocol dns_protocol_from_string(const char *s) _pure_;
 #define LLMNR_MULTICAST_IPV4_ADDRESS ((struct in_addr) { .s_addr = htobe32(224U << 24 | 252U) })
 #define LLMNR_MULTICAST_IPV6_ADDRESS ((struct in6_addr) { .s6_addr = { 0xFF, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x03 } })
 
-#define DNSKEY_FLAG_ZONE_KEY (1u << 8)
-#define DNSKEY_FLAG_SEP      (1u << 0)
-
-static inline uint16_t dnskey_to_flags(const DnsResourceRecord *rr) {
-        return (rr->dnskey.zone_key_flag * DNSKEY_FLAG_ZONE_KEY |
-                rr->dnskey.sep_flag * DNSKEY_FLAG_SEP);
-}
-
-/* http://tools.ietf.org/html/rfc4034#appendix-A.1 */
-enum {
-        DNSSEC_ALGORITHM_RSAMD5 = 1,
-        DNSSEC_ALGORITHM_DH,
-        DNSSEC_ALGORITHM_DSA,
-        DNSSEC_ALGORITHM_ECC,
-        DNSSEC_ALGORITHM_RSASHA1,
-        DNSSEC_ALGORITHM_DSA_NSEC3_SHA1,
-        DNSSEC_ALGORITHM_RSASHA1_NSEC3_SHA1,
-        DNSSEC_ALGORITHM_INDIRECT = 252,
-        DNSSEC_ALGORITHM_PRIVATEDNS,
-        DNSSEC_ALGORITHM_PRIVATEOID,
-        _DNSSEC_ALGORITHM_MAX_DEFINED
-};
-
-const char* dnssec_algorithm_to_string(int i) _const_;
-int dnssec_algorithm_from_string(const char *s) _pure_;
-
 static inline uint64_t SD_RESOLVED_FLAGS_MAKE(DnsProtocol protocol, int family) {
 
         /* Converts a protocol + family into a flags field as used in queries */
diff --git a/src/resolve/resolved-dns-question.h b/src/resolve/resolved-dns-question.h
index e77116c03a..5ffb63e250 100644
--- a/src/resolve/resolved-dns-question.h
+++ b/src/resolve/resolved-dns-question.h
@@ -23,9 +23,10 @@
 
 typedef struct DnsQuestion DnsQuestion;
 
+#include "macro.h"
 #include "resolved-dns-rr.h"
 
-/* A simple array of resources keys */
+/* A simple array of resource keys */
 
 struct DnsQuestion {
         unsigned n_ref;
@@ -55,10 +56,12 @@ const char *dns_question_first_name(DnsQuestion *q);
 
 DEFINE_TRIVIAL_CLEANUP_FUNC(DnsQuestion*, dns_question_unref);
 
-#define DNS_QUESTION_FOREACH(key, q)                                    \
-        for (unsigned _i = ({                                           \
+#define _DNS_QUESTION_FOREACH(u, key, q)                                \
+        for (unsigned UNIQ_T(i, u) = ({                                 \
                                 (key) = ((q) && (q)->n_keys > 0) ? (q)->keys[0] : NULL; \
                                 0;                                      \
                         });                                             \
-             (q) && ((_i) < (q)->n_keys);                               \
-             _i++, (key) = (_i < (q)->n_keys ? (q)->keys[_i] : NULL))
+             (q) && (UNIQ_T(i, u) < (q)->n_keys);                       \
+             UNIQ_T(i, u)++, (key) = (UNIQ_T(i, u) < (q)->n_keys ? (q)->keys[UNIQ_T(i, u)] : NULL))
+
+#define DNS_QUESTION_FOREACH(key, q) _DNS_QUESTION_FOREACH(UNIQ, key, q)
diff --git a/src/resolve/resolved-dns-rr.c b/src/resolve/resolved-dns-rr.c
index 4a1abb0cdc..281e228b12 100644
--- a/src/resolve/resolved-dns-rr.c
+++ b/src/resolve/resolved-dns-rr.c
@@ -27,6 +27,7 @@
 #include "hexdecoct.h"
 #include "resolved-dns-packet.h"
 #include "resolved-dns-rr.h"
+#include "string-table.h"
 #include "string-util.h"
 #include "strv.h"
 
@@ -416,6 +417,7 @@ DnsResourceRecord* dns_resource_record_unref(DnsResourceRecord *rr) {
                         free(rr->generic.data);
                 }
 
+                free(rr->wire_format);
                 dns_resource_key_unref(rr->key);
         }
 
@@ -576,8 +578,8 @@ int dns_resource_record_equal(const DnsResourceRecord *a, const DnsResourceRecor
                        memcmp(a->sshfp.fingerprint, b->sshfp.fingerprint, a->sshfp.fingerprint_size) == 0;
 
         case DNS_TYPE_DNSKEY:
-                return a->dnskey.zone_key_flag == b->dnskey.zone_key_flag &&
-                       a->dnskey.sep_flag == b->dnskey.sep_flag &&
+                return a->dnskey.flags == b->dnskey.flags &&
+                       a->dnskey.protocol == b->dnskey.protocol &&
                        a->dnskey.algorithm == b->dnskey.algorithm &&
                        a->dnskey.key_size == b->dnskey.key_size &&
                        memcmp(a->dnskey.key, b->dnskey.key, a->dnskey.key_size) == 0;
@@ -883,9 +885,10 @@ int dns_resource_record_to_string(const DnsResourceRecord *rr, char **ret) {
                 if (!t)
                         return -ENOMEM;
 
-                r = asprintf(&s, "%s %u 3 %.*s%.*u %s",
+                r = asprintf(&s, "%s %u %u %.*s%.*u %s",
                              k,
-                             dnskey_to_flags(rr),
+                             rr->dnskey.flags,
+                             rr->dnskey.protocol,
                              alg ? -1 : 0, alg,
                              alg ? 0 : 1, alg ? 0u : (unsigned) rr->dnskey.algorithm,
                              t);
@@ -993,6 +996,51 @@ int dns_resource_record_to_string(const DnsResourceRecord *rr, char **ret) {
         return 0;
 }
 
+int dns_resource_record_to_wire_format(DnsResourceRecord *rr, bool canonical) {
+
+        DnsPacket packet = {
+                .n_ref = 1,
+                .protocol = DNS_PROTOCOL_DNS,
+                .on_stack = true,
+                .refuse_compression = true,
+                .canonical_form = canonical,
+        };
+
+        size_t start, rds;
+        int r;
+
+        assert(rr);
+
+        /* Generates the RR in wire-format, optionally in the
+         * canonical form as discussed in the DNSSEC RFC 4034, Section
+         * 6.2. We allocate a throw-away DnsPacket object on the stack
+         * here, because we need some book-keeping for memory
+         * management, and can reuse the DnsPacket serializer, that
+         * can generate the canonical form, too, but also knows label
+         * compression and suchlike. */
+
+        if (rr->wire_format && rr->wire_format_canonical == canonical)
+                return 0;
+
+        r = dns_packet_append_rr(&packet, rr, &start, &rds);
+        if (r < 0)
+                return r;
+
+        assert(start == 0);
+        assert(packet._data);
+
+        free(rr->wire_format);
+        rr->wire_format = packet._data;
+        rr->wire_format_size = packet.size;
+        rr->wire_format_rdata_offset = rds;
+        rr->wire_format_canonical = canonical;
+
+        packet._data = NULL;
+        dns_packet_unref(&packet);
+
+        return 0;
+}
+
 const char *dns_class_to_string(uint16_t class) {
 
         switch (class) {
@@ -1049,3 +1097,25 @@ bool dns_txt_item_equal(DnsTxtItem *a, DnsTxtItem *b) {
 
         return dns_txt_item_equal(a->items_next, b->items_next);
 }
+
+static const char* const dnssec_algorithm_table[_DNSSEC_ALGORITHM_MAX_DEFINED] = {
+        [DNSSEC_ALGORITHM_RSAMD5]             = "RSAMD5",
+        [DNSSEC_ALGORITHM_DH]                 = "DH",
+        [DNSSEC_ALGORITHM_DSA]                = "DSA",
+        [DNSSEC_ALGORITHM_ECC]                = "ECC",
+        [DNSSEC_ALGORITHM_RSASHA1]            = "RSASHA1",
+        [DNSSEC_ALGORITHM_DSA_NSEC3_SHA1]     = "DSA-NSEC3-SHA1",
+        [DNSSEC_ALGORITHM_RSASHA1_NSEC3_SHA1] = "RSASHA1-NSEC3-SHA1",
+        [DNSSEC_ALGORITHM_RSASHA256]          = "RSASHA256",
+        [DNSSEC_ALGORITHM_RSASHA512]          = "RSASHA512",
+        [DNSSEC_ALGORITHM_INDIRECT]           = "INDIRECT",
+        [DNSSEC_ALGORITHM_PRIVATEDNS]         = "PRIVATEDNS",
+        [DNSSEC_ALGORITHM_PRIVATEOID]         = "PRIVATEOID",
+};
+DEFINE_STRING_TABLE_LOOKUP(dnssec_algorithm, int);
+
+static const char* const dnssec_digest_table[_DNSSEC_DIGEST_MAX_DEFINED] = {
+        [DNSSEC_DIGEST_SHA1] = "SHA1",
+        [DNSSEC_DIGEST_SHA256] = "SHA256",
+};
+DEFINE_STRING_TABLE_LOOKUP(dnssec_digest, int);
diff --git a/src/resolve/resolved-dns-rr.h b/src/resolve/resolved-dns-rr.h
index a092961823..2a103aab8d 100644
--- a/src/resolve/resolved-dns-rr.h
+++ b/src/resolve/resolved-dns-rr.h
@@ -41,6 +41,37 @@ enum {
         _DNS_CLASS_INVALID = -1
 };
 
+/* DNSKEY RR flags */
+#define DNSKEY_FLAG_ZONE_KEY (UINT16_C(1) << 8)
+#define DNSKEY_FLAG_SEP      (UINT16_C(1) << 0)
+
+/* DNSSEC algorithm identifiers, see
+ * http://tools.ietf.org/html/rfc4034#appendix-A.1 and
+ * https://www.iana.org/assignments/dns-sec-alg-numbers/dns-sec-alg-numbers.xhtml */
+enum {
+        DNSSEC_ALGORITHM_RSAMD5 = 1,
+        DNSSEC_ALGORITHM_DH,
+        DNSSEC_ALGORITHM_DSA,
+        DNSSEC_ALGORITHM_ECC,
+        DNSSEC_ALGORITHM_RSASHA1,
+        DNSSEC_ALGORITHM_DSA_NSEC3_SHA1,
+        DNSSEC_ALGORITHM_RSASHA1_NSEC3_SHA1,
+        DNSSEC_ALGORITHM_RSASHA256 = 8,  /* RFC 5702 */
+        DNSSEC_ALGORITHM_RSASHA512 = 10, /* RFC 5702 */
+        DNSSEC_ALGORITHM_INDIRECT = 252,
+        DNSSEC_ALGORITHM_PRIVATEDNS,
+        DNSSEC_ALGORITHM_PRIVATEOID,
+        _DNSSEC_ALGORITHM_MAX_DEFINED
+};
+
+/* DNSSEC digest identifiers, see
+ * https://www.iana.org/assignments/ds-rr-types/ds-rr-types.xhtml */
+enum {
+        DNSSEC_DIGEST_SHA1 = 1,
+        DNSSEC_DIGEST_SHA256 = 2,
+        _DNSSEC_DIGEST_MAX_DEFINED
+};
+
 struct DnsResourceKey {
         unsigned n_ref;
         uint16_t class, type;
@@ -57,7 +88,11 @@ struct DnsResourceRecord {
         unsigned n_ref;
         DnsResourceKey *key;
         uint32_t ttl;
-        bool unparseable;
+        bool unparseable:1;
+        bool wire_format_canonical:1;
+        void *wire_format;
+        size_t wire_format_size;
+        size_t wire_format_rdata_offset;
         union {
                 struct {
                         void *data;
@@ -135,8 +170,8 @@ struct DnsResourceRecord {
 
                 /* http://tools.ietf.org/html/rfc4034#section-2.1 */
                 struct {
-                        bool zone_key_flag:1;
-                        bool sep_flag:1;
+                        uint16_t flags;
+                        uint8_t protocol;
                         uint8_t algorithm;
                         void* key;
                         size_t key_size;
@@ -209,6 +244,8 @@ int dns_resource_record_equal(const DnsResourceRecord *a, const DnsResourceRecor
 int dns_resource_record_to_string(const DnsResourceRecord *rr, char **ret);
 DEFINE_TRIVIAL_CLEANUP_FUNC(DnsResourceRecord*, dns_resource_record_unref);
 
+int dns_resource_record_to_wire_format(DnsResourceRecord *rr, bool canonical);
+
 DnsTxtItem *dns_txt_item_free_all(DnsTxtItem *i);
 bool dns_txt_item_equal(DnsTxtItem *a, DnsTxtItem *b);
 
@@ -216,3 +253,9 @@ const char *dns_class_to_string(uint16_t type);
 int dns_class_from_string(const char *name, uint16_t *class);
 
 extern const struct hash_ops dns_resource_key_hash_ops;
+
+const char* dnssec_algorithm_to_string(int i) _const_;
+int dnssec_algorithm_from_string(const char *s) _pure_;
+
+const char *dnssec_digest_to_string(int i) _const_;
+int dnssec_digest_from_string(const char *s) _pure_;
diff --git a/src/resolve/resolved-dns-scope.c b/src/resolve/resolved-dns-scope.c
index 09e6872d26..846280e8b8 100644
--- a/src/resolve/resolved-dns-scope.c
+++ b/src/resolve/resolved-dns-scope.c
@@ -549,7 +549,7 @@ static int dns_scope_make_reply_packet(
 
         if (answer) {
                 for (i = 0; i < answer->n_rrs; i++) {
-                        r = dns_packet_append_rr(p, answer->items[i].rr, NULL);
+                        r = dns_packet_append_rr(p, answer->items[i].rr, NULL, NULL);
                         if (r < 0)
                                 return r;
                 }
@@ -559,7 +559,7 @@ static int dns_scope_make_reply_packet(
 
         if (soa) {
                 for (i = 0; i < soa->n_rrs; i++) {
-                        r = dns_packet_append_rr(p, soa->items[i].rr, NULL);
+                        r = dns_packet_append_rr(p, soa->items[i].rr, NULL, NULL);
                         if (r < 0)
                                 return r;
                 }
@@ -733,7 +733,7 @@ static int dns_scope_make_conflict_packet(
         if (r < 0)
                 return r;
 
-        r = dns_packet_append_rr(p, rr, NULL);
+        r = dns_packet_append_rr(p, rr, NULL, NULL);
         if (r < 0)
                 return r;
 
diff --git a/src/resolve/test-dnssec.c b/src/resolve/test-dnssec.c
new file mode 100644
index 0000000000..0b2ffeeddd
--- /dev/null
+++ b/src/resolve/test-dnssec.c
@@ -0,0 +1,217 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2015 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <sys/socket.h>
+
+#include "alloc-util.h"
+#include "resolved-dns-dnssec.h"
+#include "resolved-dns-rr.h"
+#include "string-util.h"
+
+static void test_dnssec_verify_rrset(void) {
+
+        static const uint8_t signature_blob[] = {
+                0x7f, 0x79, 0xdd, 0x5e, 0x89, 0x79, 0x18, 0xd0, 0x34, 0x86, 0x8c, 0x72, 0x77, 0x75, 0x48, 0x4d,
+                0xc3, 0x7d, 0x38, 0x04, 0xab, 0xcd, 0x9e, 0x4c, 0x82, 0xb0, 0x92, 0xca, 0xe9, 0x66, 0xe9, 0x6e,
+                0x47, 0xc7, 0x68, 0x8c, 0x94, 0xf6, 0x69, 0xcb, 0x75, 0x94, 0xe6, 0x30, 0xa6, 0xfb, 0x68, 0x64,
+                0x96, 0x1a, 0x84, 0xe1, 0xdc, 0x16, 0x4c, 0x83, 0x6c, 0x44, 0xf2, 0x74, 0x4d, 0x74, 0x79, 0x8f,
+                0xf3, 0xf4, 0x63, 0x0d, 0xef, 0x5a, 0xe7, 0xe2, 0xfd, 0xf2, 0x2b, 0x38, 0x7c, 0x28, 0x96, 0x9d,
+                0xb6, 0xcd, 0x5c, 0x3b, 0x57, 0xe2, 0x24, 0x78, 0x65, 0xd0, 0x9e, 0x77, 0x83, 0x09, 0x6c, 0xff,
+                0x3d, 0x52, 0x3f, 0x6e, 0xd1, 0xed, 0x2e, 0xf9, 0xee, 0x8e, 0xa6, 0xbe, 0x9a, 0xa8, 0x87, 0x76,
+                0xd8, 0x77, 0xcc, 0x96, 0xa0, 0x98, 0xa1, 0xd1, 0x68, 0x09, 0x43, 0xcf, 0x56, 0xd9, 0xd1, 0x66,
+        };
+
+        static const uint8_t dnskey_blob[] = {
+                0x03, 0x01, 0x00, 0x01, 0x9b, 0x49, 0x9b, 0xc1, 0xf9, 0x9a, 0xe0, 0x4e, 0xcf, 0xcb, 0x14, 0x45,
+                0x2e, 0xc9, 0xf9, 0x74, 0xa7, 0x18, 0xb5, 0xf3, 0xde, 0x39, 0x49, 0xdf, 0x63, 0x33, 0x97, 0x52,
+                0xe0, 0x8e, 0xac, 0x50, 0x30, 0x8e, 0x09, 0xd5, 0x24, 0x3d, 0x26, 0xa4, 0x49, 0x37, 0x2b, 0xb0,
+                0x6b, 0x1b, 0xdf, 0xde, 0x85, 0x83, 0xcb, 0x22, 0x4e, 0x60, 0x0a, 0x91, 0x1a, 0x1f, 0xc5, 0x40,
+                0xb1, 0xc3, 0x15, 0xc1, 0x54, 0x77, 0x86, 0x65, 0x53, 0xec, 0x10, 0x90, 0x0c, 0x91, 0x00, 0x5e,
+                0x15, 0xdc, 0x08, 0x02, 0x4c, 0x8c, 0x0d, 0xc0, 0xac, 0x6e, 0xc4, 0x3e, 0x1b, 0x80, 0x19, 0xe4,
+                0xf7, 0x5f, 0x77, 0x51, 0x06, 0x87, 0x61, 0xde, 0xa2, 0x18, 0x0f, 0x40, 0x8b, 0x79, 0x72, 0xfa,
+                0x8d, 0x1a, 0x44, 0x47, 0x0d, 0x8e, 0x3a, 0x2d, 0xc7, 0x39, 0xbf, 0x56, 0x28, 0x97, 0xd9, 0x20,
+                0x4f, 0x00, 0x51, 0x3b,
+        };
+
+        _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *a = NULL, *rrsig = NULL, *dnskey = NULL;
+        _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
+        _cleanup_free_ char *x = NULL, *y = NULL, *z = NULL;
+
+        a = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_A, "nAsA.gov");
+        assert_se(a);
+
+        a->a.in_addr.s_addr = inet_addr("52.0.14.116");
+
+        assert_se(dns_resource_record_to_string(a, &x) >= 0);
+        log_info("A: %s", x);
+
+        rrsig = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_RRSIG, "NaSa.GOV.");
+        assert_se(rrsig);
+
+        rrsig->rrsig.type_covered = DNS_TYPE_A;
+        rrsig->rrsig.algorithm = DNSSEC_ALGORITHM_RSASHA256;
+        rrsig->rrsig.labels = 2;
+        rrsig->rrsig.original_ttl = 600;
+        rrsig->rrsig.expiration = 0x5683135c;
+        rrsig->rrsig.inception = 0x565b7da8;
+        rrsig->rrsig.key_tag = 63876;
+        rrsig->rrsig.signer = strdup("Nasa.Gov.");
+        assert_se(rrsig->rrsig.signer);
+        rrsig->rrsig.signature_size = sizeof(signature_blob);
+        rrsig->rrsig.signature = memdup(signature_blob, rrsig->rrsig.signature_size);
+        assert_se(rrsig->rrsig.signature);
+
+        assert_se(dns_resource_record_to_string(rrsig, &y) >= 0);
+        log_info("RRSIG: %s", y);
+
+        dnskey = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_DNSKEY, "nASA.gOV");
+        assert_se(dnskey);
+
+        dnskey->dnskey.flags = 256;
+        dnskey->dnskey.protocol = 3;
+        dnskey->dnskey.algorithm = DNSSEC_ALGORITHM_RSASHA256;
+        dnskey->dnskey.key_size = sizeof(dnskey_blob);
+        dnskey->dnskey.key = memdup(dnskey_blob, sizeof(dnskey_blob));
+        assert_se(dnskey->dnskey.key);
+
+        assert_se(dns_resource_record_to_string(dnskey, &z) >= 0);
+        log_info("DNSKEY: %s", z);
+        log_info("DNSKEY keytag: %u", dnssec_keytag(dnskey));
+
+        assert_se(dnssec_key_match_rrsig(a->key, rrsig) > 0);
+        assert_se(dnssec_rrsig_match_dnskey(rrsig, dnskey) > 0);
+
+        answer = dns_answer_new(1);
+        assert_se(answer);
+        assert_se(dns_answer_add(answer, a, 0) >= 0);
+
+        /* Validate the RR as it if was 2015-12-2 today */
+        assert_se(dnssec_verify_rrset(answer, a->key, rrsig, dnskey, 1449092754*USEC_PER_SEC) == DNSSEC_VERIFIED);
+}
+
+static void test_dnssec_verify_dns_key(void) {
+
+        static const uint8_t ds1_fprint[] = {
+                0x46, 0x8B, 0xC8, 0xDD, 0xC7, 0xE8, 0x27, 0x03, 0x40, 0xBB, 0x8A, 0x1F, 0x3B, 0x2E, 0x45, 0x9D,
+                0x80, 0x67, 0x14, 0x01,
+        };
+        static const uint8_t ds2_fprint[] = {
+                0x8A, 0xEE, 0x80, 0x47, 0x05, 0x5F, 0x83, 0xD1, 0x48, 0xBA, 0x8F, 0xF6, 0xDD, 0xA7, 0x60, 0xCE,
+                0x94, 0xF7, 0xC7, 0x5E, 0x52, 0x4C, 0xF2, 0xE9, 0x50, 0xB9, 0x2E, 0xCB, 0xEF, 0x96, 0xB9, 0x98,
+        };
+        static const uint8_t dnskey_blob[] = {
+                0x03, 0x01, 0x00, 0x01, 0xa8, 0x12, 0xda, 0x4f, 0xd2, 0x7d, 0x54, 0x14, 0x0e, 0xcc, 0x5b, 0x5e,
+                0x45, 0x9c, 0x96, 0x98, 0xc0, 0xc0, 0x85, 0x81, 0xb1, 0x47, 0x8c, 0x7d, 0xe8, 0x39, 0x50, 0xcc,
+                0xc5, 0xd0, 0xf2, 0x00, 0x81, 0x67, 0x79, 0xf6, 0xcc, 0x9d, 0xad, 0x6c, 0xbb, 0x7b, 0x6f, 0x48,
+                0x97, 0x15, 0x1c, 0xfd, 0x0b, 0xfe, 0xd3, 0xd7, 0x7d, 0x9f, 0x81, 0x26, 0xd3, 0xc5, 0x65, 0x49,
+                0xcf, 0x46, 0x62, 0xb0, 0x55, 0x6e, 0x47, 0xc7, 0x30, 0xef, 0x51, 0xfb, 0x3e, 0xc6, 0xef, 0xde,
+                0x27, 0x3f, 0xfa, 0x57, 0x2d, 0xa7, 0x1d, 0x80, 0x46, 0x9a, 0x5f, 0x14, 0xb3, 0xb0, 0x2c, 0xbe,
+                0x72, 0xca, 0xdf, 0xb2, 0xff, 0x36, 0x5b, 0x4f, 0xec, 0x58, 0x8e, 0x8d, 0x01, 0xe9, 0xa9, 0xdf,
+                0xb5, 0x60, 0xad, 0x52, 0x4d, 0xfc, 0xa9, 0x3e, 0x8d, 0x35, 0x95, 0xb3, 0x4e, 0x0f, 0xca, 0x45,
+                0x1b, 0xf7, 0xef, 0x3a, 0x88, 0x25, 0x08, 0xc7, 0x4e, 0x06, 0xc1, 0x62, 0x1a, 0xce, 0xd8, 0x77,
+                0xbd, 0x02, 0x65, 0xf8, 0x49, 0xfb, 0xce, 0xf6, 0xa8, 0x09, 0xfc, 0xde, 0xb2, 0x09, 0x9d, 0x39,
+                0xf8, 0x63, 0x9c, 0x32, 0x42, 0x7c, 0xa0, 0x30, 0x86, 0x72, 0x7a, 0x4a, 0xc6, 0xd4, 0xb3, 0x2d,
+                0x24, 0xef, 0x96, 0x3f, 0xc2, 0xda, 0xd3, 0xf2, 0x15, 0x6f, 0xda, 0x65, 0x4b, 0x81, 0x28, 0x68,
+                0xf4, 0xfe, 0x3e, 0x71, 0x4f, 0x50, 0x96, 0x72, 0x58, 0xa1, 0x89, 0xdd, 0x01, 0x61, 0x39, 0x39,
+                0xc6, 0x76, 0xa4, 0xda, 0x02, 0x70, 0x3d, 0xc0, 0xdc, 0x8d, 0x70, 0x72, 0x04, 0x90, 0x79, 0xd4,
+                0xec, 0x65, 0xcf, 0x49, 0x35, 0x25, 0x3a, 0x14, 0x1a, 0x45, 0x20, 0xeb, 0x31, 0xaf, 0x92, 0xba,
+                0x20, 0xd3, 0xcd, 0xa7, 0x13, 0x44, 0xdc, 0xcf, 0xf0, 0x27, 0x34, 0xb9, 0xe7, 0x24, 0x6f, 0x73,
+                0xe7, 0xea, 0x77, 0x03,
+        };
+
+        _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *dnskey = NULL, *ds1 = NULL, *ds2 = NULL;
+        _cleanup_free_ char *a = NULL, *b = NULL, *c = NULL;
+
+        /* The two DS RRs in effect for nasa.gov on 2015-12-01. */
+        ds1 = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_DS, "nasa.gov");
+        assert_se(ds1);
+
+        ds1->ds.key_tag = 47857;
+        ds1->ds.algorithm = DNSSEC_ALGORITHM_RSASHA256;
+        ds1->ds.digest_type = DNSSEC_DIGEST_SHA1;
+        ds1->ds.digest_size = sizeof(ds1_fprint);
+        ds1->ds.digest = memdup(ds1_fprint, ds1->ds.digest_size);
+        assert_se(ds1->ds.digest);
+
+        assert_se(dns_resource_record_to_string(ds1, &a) >= 0);
+        log_info("DS1: %s", a);
+
+        ds2 = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_DS, "NASA.GOV");
+        assert_se(ds2);
+
+        ds2->ds.key_tag = 47857;
+        ds2->ds.algorithm = DNSSEC_ALGORITHM_RSASHA256;
+        ds2->ds.digest_type = DNSSEC_DIGEST_SHA256;
+        ds2->ds.digest_size = sizeof(ds2_fprint);
+        ds2->ds.digest = memdup(ds2_fprint, ds2->ds.digest_size);
+        assert_se(ds2->ds.digest);
+
+        assert_se(dns_resource_record_to_string(ds2, &b) >= 0);
+        log_info("DS2: %s", b);
+
+        dnskey = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_DNSKEY, "nasa.GOV");
+        assert_se(dnskey);
+
+        dnskey->dnskey.flags = 257;
+        dnskey->dnskey.protocol = 3;
+        dnskey->dnskey.algorithm = DNSSEC_ALGORITHM_RSASHA256;
+        dnskey->dnskey.key_size = sizeof(dnskey_blob);
+        dnskey->dnskey.key = memdup(dnskey_blob, sizeof(dnskey_blob));
+        assert_se(dnskey->dnskey.key);
+
+        assert_se(dns_resource_record_to_string(dnskey, &c) >= 0);
+        log_info("DNSKEY: %s", c);
+        log_info("DNSKEY keytag: %u", dnssec_keytag(dnskey));
+
+        assert_se(dnssec_verify_dnskey(dnskey, ds1) > 0);
+        assert_se(dnssec_verify_dnskey(dnskey, ds2) > 0);
+}
+
+static void test_dnssec_canonicalize_one(const char *original, const char *canonical, int r) {
+        char canonicalized[DNSSEC_CANONICAL_HOSTNAME_MAX];
+
+        assert_se(dnssec_canonicalize(original, canonicalized, sizeof(canonicalized)) == r);
+        if (r < 0)
+                return;
+
+        assert_se(streq(canonicalized, canonical));
+}
+
+static void test_dnssec_canonicalize(void) {
+        test_dnssec_canonicalize_one("", ".", 1);
+        test_dnssec_canonicalize_one(".", ".", 1);
+        test_dnssec_canonicalize_one("foo", "foo.", 4);
+        test_dnssec_canonicalize_one("foo.", "foo.", 4);
+        test_dnssec_canonicalize_one("FOO.", "foo.", 4);
+        test_dnssec_canonicalize_one("FOO.bar.", "foo.bar.", 8);
+        test_dnssec_canonicalize_one("FOO..bar.", NULL, -EINVAL);
+}
+
+int main(int argc, char*argv[]) {
+
+        test_dnssec_canonicalize();
+        test_dnssec_verify_dns_key();
+        test_dnssec_verify_rrset();
+
+        return 0;
+}
diff --git a/src/shared/dns-domain.c b/src/shared/dns-domain.c
index 5ac8ad5b7a..429aa6d2cb 100644
--- a/src/shared/dns-domain.c
+++ b/src/shared/dns-domain.c
@@ -865,7 +865,7 @@ bool dns_name_is_single_label(const char *name) {
 }
 
 /* Encode a domain name according to RFC 1035 Section 3.1, without compression */
-int dns_name_to_wire_format(const char *domain, uint8_t *buffer, size_t len) {
+int dns_name_to_wire_format(const char *domain, uint8_t *buffer, size_t len, bool canonical) {
         uint8_t *label_length, *out;
         int r;
 
@@ -890,6 +890,20 @@ int dns_name_to_wire_format(const char *domain, uint8_t *buffer, size_t len) {
                 if (r < 0)
                         return r;
 
+                if (canonical) {
+                        size_t i;
+
+                        /* Optionally, output the name in DNSSEC
+                         * canonical format, as described in RFC 4034,
+                         * section 6.2. Or in other words: in
+                         * lower-case. */
+
+                        for (i = 0; i < (size_t) r; i++) {
+                                if (out[i] >= 'A' && out[i] <= 'Z')
+                                        out[i] = out[i] - 'A' + 'a';
+                        }
+                }
+
                 /* Fill label length, move forward */
                 *label_length = r;
                 out += r;
diff --git a/src/shared/dns-domain.h b/src/shared/dns-domain.h
index 44a9975541..e48d8c6b9d 100644
--- a/src/shared/dns-domain.h
+++ b/src/shared/dns-domain.h
@@ -34,6 +34,9 @@
 /* Maximum length of a full hostname, consisting of a series of unescaped labels, and no trailing dot or NUL byte */
 #define DNS_HOSTNAME_MAX 253
 
+/* Maximum length of a full hostname, on the wire, including the final NUL byte */
+#define DNS_WIRE_FOMAT_HOSTNAME_MAX 255
+
 int dns_label_unescape(const char **name, char *dest, size_t sz);
 int dns_label_unescape_suffix(const char *name, const char **label_end, char *dest, size_t sz);
 int dns_label_escape(const char *p, size_t l, char *dest, size_t sz);
@@ -77,7 +80,7 @@ int dns_name_address(const char *p, int *family, union in_addr_union *a);
 bool dns_name_is_root(const char *name);
 bool dns_name_is_single_label(const char *name);
 
-int dns_name_to_wire_format(const char *domain, uint8_t *buffer, size_t len);
+int dns_name_to_wire_format(const char *domain, uint8_t *buffer, size_t len, bool canonical);
 
 bool dns_srv_type_is_valid(const char *name);
 bool dns_service_name_is_valid(const char *name);
diff --git a/src/test/test-dns-domain.c b/src/test/test-dns-domain.c
index 7f53a8cc56..de003e251c 100644
--- a/src/test/test-dns-domain.c
+++ b/src/test/test-dns-domain.c
@@ -56,7 +56,7 @@ static void test_dns_name_to_wire_format_one(const char *what, const char *expec
         uint8_t buffer[buffer_sz];
         int r;
 
-        r = dns_name_to_wire_format(what, buffer, buffer_sz);
+        r = dns_name_to_wire_format(what, buffer, buffer_sz, false);
         assert_se(r == ret);
 
         if (r < 0)