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-rw-r--r--crypto/dh_helper.c95
1 files changed, 95 insertions, 0 deletions
diff --git a/crypto/dh_helper.c b/crypto/dh_helper.c
new file mode 100644
index 000000000..02db76b20
--- /dev/null
+++ b/crypto/dh_helper.c
@@ -0,0 +1,95 @@
+/*
+ * Copyright (c) 2016, Intel Corporation
+ * Authors: Salvatore Benedetto <salvatore.benedetto@intel.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/err.h>
+#include <linux/string.h>
+#include <crypto/dh.h>
+#include <crypto/kpp.h>
+
+#define DH_KPP_SECRET_MIN_SIZE (sizeof(struct kpp_secret) + 3 * sizeof(int))
+
+static inline u8 *dh_pack_data(void *dst, const void *src, size_t size)
+{
+ memcpy(dst, src, size);
+ return dst + size;
+}
+
+static inline const u8 *dh_unpack_data(void *dst, const void *src, size_t size)
+{
+ memcpy(dst, src, size);
+ return src + size;
+}
+
+static inline int dh_data_size(const struct dh *p)
+{
+ return p->key_size + p->p_size + p->g_size;
+}
+
+int crypto_dh_key_len(const struct dh *p)
+{
+ return DH_KPP_SECRET_MIN_SIZE + dh_data_size(p);
+}
+EXPORT_SYMBOL_GPL(crypto_dh_key_len);
+
+int crypto_dh_encode_key(char *buf, unsigned int len, const struct dh *params)
+{
+ u8 *ptr = buf;
+ struct kpp_secret secret = {
+ .type = CRYPTO_KPP_SECRET_TYPE_DH,
+ .len = len
+ };
+
+ if (unlikely(!buf))
+ return -EINVAL;
+
+ if (len != crypto_dh_key_len(params))
+ return -EINVAL;
+
+ ptr = dh_pack_data(ptr, &secret, sizeof(secret));
+ ptr = dh_pack_data(ptr, &params->key_size, sizeof(params->key_size));
+ ptr = dh_pack_data(ptr, &params->p_size, sizeof(params->p_size));
+ ptr = dh_pack_data(ptr, &params->g_size, sizeof(params->g_size));
+ ptr = dh_pack_data(ptr, params->key, params->key_size);
+ ptr = dh_pack_data(ptr, params->p, params->p_size);
+ dh_pack_data(ptr, params->g, params->g_size);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(crypto_dh_encode_key);
+
+int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params)
+{
+ const u8 *ptr = buf;
+ struct kpp_secret secret;
+
+ if (unlikely(!buf || len < DH_KPP_SECRET_MIN_SIZE))
+ return -EINVAL;
+
+ ptr = dh_unpack_data(&secret, ptr, sizeof(secret));
+ if (secret.type != CRYPTO_KPP_SECRET_TYPE_DH)
+ return -EINVAL;
+
+ ptr = dh_unpack_data(&params->key_size, ptr, sizeof(params->key_size));
+ ptr = dh_unpack_data(&params->p_size, ptr, sizeof(params->p_size));
+ ptr = dh_unpack_data(&params->g_size, ptr, sizeof(params->g_size));
+ if (secret.len != crypto_dh_key_len(params))
+ return -EINVAL;
+
+ /* Don't allocate memory. Set pointers to data within
+ * the given buffer
+ */
+ params->key = (void *)ptr;
+ params->p = (void *)(ptr + params->key_size);
+ params->g = (void *)(ptr + params->key_size + params->p_size);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(crypto_dh_decode_key);