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-rw-r--r--crypto/ecdh_helper.c83
1 files changed, 83 insertions, 0 deletions
diff --git a/crypto/ecdh_helper.c b/crypto/ecdh_helper.c
new file mode 100644
index 000000000..f18f9028f
--- /dev/null
+++ b/crypto/ecdh_helper.c
@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2016, Intel Corporation
+ * Authors: Salvatore Benedetto <salvatore.benedetto@intel.com>
+ */
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/err.h>
+#include <linux/string.h>
+#include <crypto/ecdh.h>
+#include <crypto/kpp.h>
+
+#define ECDH_KPP_SECRET_MIN_SIZE (sizeof(struct kpp_secret) + sizeof(short))
+
+static inline u8 *ecdh_pack_data(void *dst, const void *src, size_t sz)
+{
+ memcpy(dst, src, sz);
+ return dst + sz;
+}
+
+static inline const u8 *ecdh_unpack_data(void *dst, const void *src, size_t sz)
+{
+ memcpy(dst, src, sz);
+ return src + sz;
+}
+
+unsigned int crypto_ecdh_key_len(const struct ecdh *params)
+{
+ return ECDH_KPP_SECRET_MIN_SIZE + params->key_size;
+}
+EXPORT_SYMBOL_GPL(crypto_ecdh_key_len);
+
+int crypto_ecdh_encode_key(char *buf, unsigned int len,
+ const struct ecdh *params)
+{
+ u8 *ptr = buf;
+ struct kpp_secret secret = {
+ .type = CRYPTO_KPP_SECRET_TYPE_ECDH,
+ .len = len
+ };
+
+ if (unlikely(!buf))
+ return -EINVAL;
+
+ if (len != crypto_ecdh_key_len(params))
+ return -EINVAL;
+
+ ptr = ecdh_pack_data(ptr, &secret, sizeof(secret));
+ ptr = ecdh_pack_data(ptr, &params->key_size, sizeof(params->key_size));
+ ecdh_pack_data(ptr, params->key, params->key_size);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(crypto_ecdh_encode_key);
+
+int crypto_ecdh_decode_key(const char *buf, unsigned int len,
+ struct ecdh *params)
+{
+ const u8 *ptr = buf;
+ struct kpp_secret secret;
+
+ if (unlikely(!buf || len < ECDH_KPP_SECRET_MIN_SIZE))
+ return -EINVAL;
+
+ ptr = ecdh_unpack_data(&secret, ptr, sizeof(secret));
+ if (secret.type != CRYPTO_KPP_SECRET_TYPE_ECDH)
+ return -EINVAL;
+
+ if (unlikely(len < secret.len))
+ return -EINVAL;
+
+ ptr = ecdh_unpack_data(&params->key_size, ptr, sizeof(params->key_size));
+ if (secret.len != crypto_ecdh_key_len(params))
+ return -EINVAL;
+
+ /* Don't allocate memory. Set pointer to data
+ * within the given buffer
+ */
+ params->key = (void *)ptr;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(crypto_ecdh_decode_key);