/*
- * Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
+ * Copyright 2016-2018 The OpenSSL Project Authors. All Rights Reserved.
*
- * Licensed under the OpenSSL license (the "License"). You may not use
+ * Licensed under the Apache License 2.0 (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#include <stdlib.h>
+#include <stdarg.h>
#include <string.h>
#include <openssl/hmac.h>
-#include <openssl/kdf.h>
#include <openssl/evp.h>
+#include <openssl/kdf.h>
#include "internal/cryptlib.h"
+#include "internal/numbers.h"
#include "internal/evp_int.h"
+#include "kdf_local.h"
#define HKDF_MAXBUF 1024
-static unsigned char *HKDF(const EVP_MD *evp_md,
- const unsigned char *salt, size_t salt_len,
- const unsigned char *key, size_t key_len,
- const unsigned char *info, size_t info_len,
- unsigned char *okm, size_t okm_len);
-
-static unsigned char *HKDF_Extract(const EVP_MD *evp_md,
- const unsigned char *salt, size_t salt_len,
- const unsigned char *key, size_t key_len,
- unsigned char *prk, size_t *prk_len);
-
-static unsigned char *HKDF_Expand(const EVP_MD *evp_md,
- const unsigned char *prk, size_t prk_len,
- const unsigned char *info, size_t info_len,
- unsigned char *okm, size_t okm_len);
-
-typedef struct {
+static void kdf_hkdf_reset(EVP_KDF_IMPL *impl);
+static int HKDF(const EVP_MD *evp_md,
+ const unsigned char *salt, size_t salt_len,
+ const unsigned char *key, size_t key_len,
+ const unsigned char *info, size_t info_len,
+ unsigned char *okm, size_t okm_len);
+static int HKDF_Extract(const EVP_MD *evp_md,
+ const unsigned char *salt, size_t salt_len,
+ const unsigned char *ikm, size_t ikm_len,
+ unsigned char *prk, size_t prk_len);
+static int HKDF_Expand(const EVP_MD *evp_md,
+ const unsigned char *prk, size_t prk_len,
+ const unsigned char *info, size_t info_len,
+ unsigned char *okm, size_t okm_len);
+
+struct evp_kdf_impl_st {
+ int mode;
const EVP_MD *md;
unsigned char *salt;
size_t salt_len;
size_t key_len;
unsigned char info[HKDF_MAXBUF];
size_t info_len;
-} HKDF_PKEY_CTX;
+};
-static int pkey_hkdf_init(EVP_PKEY_CTX *ctx)
+static EVP_KDF_IMPL *kdf_hkdf_new(void)
{
- HKDF_PKEY_CTX *kctx;
-
- kctx = OPENSSL_zalloc(sizeof(*kctx));
- if (kctx == NULL)
- return 0;
+ EVP_KDF_IMPL *impl;
- ctx->data = kctx;
+ if ((impl = OPENSSL_zalloc(sizeof(*impl))) == NULL)
+ KDFerr(KDF_F_KDF_HKDF_NEW, ERR_R_MALLOC_FAILURE);
+ return impl;
+}
- return 1;
+static void kdf_hkdf_free(EVP_KDF_IMPL *impl)
+{
+ kdf_hkdf_reset(impl);
+ OPENSSL_free(impl);
}
-static void pkey_hkdf_cleanup(EVP_PKEY_CTX *ctx)
+static void kdf_hkdf_reset(EVP_KDF_IMPL *impl)
{
- HKDF_PKEY_CTX *kctx = ctx->data;
- OPENSSL_clear_free(kctx->salt, kctx->salt_len);
- OPENSSL_clear_free(kctx->key, kctx->key_len);
- OPENSSL_cleanse(kctx->info, kctx->info_len);
- OPENSSL_free(kctx);
+ OPENSSL_free(impl->salt);
+ OPENSSL_clear_free(impl->key, impl->key_len);
+ OPENSSL_cleanse(impl->info, impl->info_len);
+ memset(impl, 0, sizeof(*impl));
}
-static int pkey_hkdf_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
+static int kdf_hkdf_ctrl(EVP_KDF_IMPL *impl, int cmd, va_list args)
{
- HKDF_PKEY_CTX *kctx = ctx->data;
+ const unsigned char *p;
+ size_t len;
+ const EVP_MD *md;
- switch (type) {
- case EVP_PKEY_CTRL_HKDF_MD:
- if (p2 == NULL)
+ switch (cmd) {
+ case EVP_KDF_CTRL_SET_MD:
+ md = va_arg(args, const EVP_MD *);
+ if (md == NULL)
return 0;
- kctx->md = p2;
+ impl->md = md;
return 1;
- case EVP_PKEY_CTRL_HKDF_SALT:
- if (p1 == 0 || p2 == NULL)
- return 1;
-
- if (p1 < 0)
- return 0;
+ case EVP_KDF_CTRL_SET_HKDF_MODE:
+ impl->mode = va_arg(args, int);
+ return 1;
- if (kctx->salt != NULL)
- OPENSSL_clear_free(kctx->salt, kctx->salt_len);
+ case EVP_KDF_CTRL_SET_SALT:
+ p = va_arg(args, const unsigned char *);
+ len = va_arg(args, size_t);
+ if (len == 0 || p == NULL)
+ return 1;
- kctx->salt = OPENSSL_memdup(p2, p1);
- if (kctx->salt == NULL)
+ OPENSSL_free(impl->salt);
+ impl->salt = OPENSSL_memdup(p, len);
+ if (impl->salt == NULL)
return 0;
- kctx->salt_len = p1;
+ impl->salt_len = len;
return 1;
- case EVP_PKEY_CTRL_HKDF_KEY:
- if (p1 < 0)
+ case EVP_KDF_CTRL_SET_KEY:
+ p = va_arg(args, const unsigned char *);
+ len = va_arg(args, size_t);
+ OPENSSL_clear_free(impl->key, impl->key_len);
+ impl->key = OPENSSL_memdup(p, len);
+ if (impl->key == NULL)
return 0;
- if (kctx->key != NULL)
- OPENSSL_clear_free(kctx->key, kctx->key_len);
-
- kctx->key = OPENSSL_memdup(p2, p1);
- if (kctx->key == NULL)
- return 0;
+ impl->key_len = len;
+ return 1;
- kctx->key_len = p1;
+ case EVP_KDF_CTRL_RESET_HKDF_INFO:
+ OPENSSL_cleanse(impl->info, impl->info_len);
+ impl->info_len = 0;
return 1;
- case EVP_PKEY_CTRL_HKDF_INFO:
- if (p1 == 0 || p2 == NULL)
+ case EVP_KDF_CTRL_ADD_HKDF_INFO:
+ p = va_arg(args, const unsigned char *);
+ len = va_arg(args, size_t);
+ if (len == 0 || p == NULL)
return 1;
- if (p1 < 0 || p1 > (int)(HKDF_MAXBUF - kctx->info_len))
+ if (len > (HKDF_MAXBUF - impl->info_len))
return 0;
- memcpy(kctx->info + kctx->info_len, p2, p1);
- kctx->info_len += p1;
+ memcpy(impl->info + impl->info_len, p, len);
+ impl->info_len += len;
return 1;
default:
return -2;
-
}
}
-static int pkey_hkdf_ctrl_str(EVP_PKEY_CTX *ctx, const char *type,
- const char *value)
+static int kdf_hkdf_ctrl_str(EVP_KDF_IMPL *impl, const char *type,
+ const char *value)
{
- if (strcmp(type, "md") == 0)
- return EVP_PKEY_CTX_set_hkdf_md(ctx, EVP_get_digestbyname(value));
+ if (strcmp(type, "mode") == 0) {
+ int mode;
+
+ if (strcmp(value, "EXTRACT_AND_EXPAND") == 0)
+ mode = EVP_KDF_HKDF_MODE_EXTRACT_AND_EXPAND;
+ else if (strcmp(value, "EXTRACT_ONLY") == 0)
+ mode = EVP_KDF_HKDF_MODE_EXTRACT_ONLY;
+ else if (strcmp(value, "EXPAND_ONLY") == 0)
+ mode = EVP_KDF_HKDF_MODE_EXPAND_ONLY;
+ else
+ return 0;
+
+ return call_ctrl(kdf_hkdf_ctrl, impl, EVP_KDF_CTRL_SET_HKDF_MODE, mode);
+ }
+
+ if (strcmp(type, "digest") == 0)
+ return kdf_md2ctrl(impl, kdf_hkdf_ctrl, EVP_KDF_CTRL_SET_MD, value);
if (strcmp(type, "salt") == 0)
- return EVP_PKEY_CTX_str2ctrl(ctx, EVP_PKEY_CTRL_HKDF_SALT, value);
+ return kdf_str2ctrl(impl, kdf_hkdf_ctrl, EVP_KDF_CTRL_SET_SALT, value);
if (strcmp(type, "hexsalt") == 0)
- return EVP_PKEY_CTX_hex2ctrl(ctx, EVP_PKEY_CTRL_HKDF_SALT, value);
+ return kdf_hex2ctrl(impl, kdf_hkdf_ctrl, EVP_KDF_CTRL_SET_SALT, value);
if (strcmp(type, "key") == 0)
- return EVP_PKEY_CTX_str2ctrl(ctx, EVP_PKEY_CTRL_HKDF_KEY, value);
+ return kdf_str2ctrl(impl, kdf_hkdf_ctrl, EVP_KDF_CTRL_SET_KEY, value);
if (strcmp(type, "hexkey") == 0)
- return EVP_PKEY_CTX_hex2ctrl(ctx, EVP_PKEY_CTRL_HKDF_KEY, value);
+ return kdf_hex2ctrl(impl, kdf_hkdf_ctrl, EVP_KDF_CTRL_SET_KEY, value);
if (strcmp(type, "info") == 0)
- return EVP_PKEY_CTX_str2ctrl(ctx, EVP_PKEY_CTRL_HKDF_INFO, value);
+ return kdf_str2ctrl(impl, kdf_hkdf_ctrl, EVP_KDF_CTRL_ADD_HKDF_INFO,
+ value);
if (strcmp(type, "hexinfo") == 0)
- return EVP_PKEY_CTX_hex2ctrl(ctx, EVP_PKEY_CTRL_HKDF_INFO, value);
+ return kdf_hex2ctrl(impl, kdf_hkdf_ctrl, EVP_KDF_CTRL_ADD_HKDF_INFO,
+ value);
return -2;
}
-static int pkey_hkdf_derive(EVP_PKEY_CTX *ctx, unsigned char *key,
- size_t *keylen)
+static size_t kdf_hkdf_size(EVP_KDF_IMPL *impl)
{
- HKDF_PKEY_CTX *kctx = ctx->data;
+ int sz;
- if (kctx->md == NULL || kctx->key == NULL)
- return 0;
+ if (impl->mode != EVP_KDF_HKDF_MODE_EXTRACT_ONLY)
+ return SIZE_MAX;
- if (HKDF(kctx->md, kctx->salt, kctx->salt_len, kctx->key, kctx->key_len,
- kctx->info, kctx->info_len, key, *keylen) == NULL)
- {
+ if (impl->md == NULL) {
+ KDFerr(KDF_F_KDF_HKDF_SIZE, KDF_R_MISSING_MESSAGE_DIGEST);
return 0;
}
+ sz = EVP_MD_size(impl->md);
+ if (sz < 0)
+ return 0;
- return 1;
+ return sz;
}
-const EVP_PKEY_METHOD hkdf_pkey_meth = {
- EVP_PKEY_HKDF,
- 0,
- pkey_hkdf_init,
- 0,
- pkey_hkdf_cleanup,
-
- 0, 0,
- 0, 0,
-
- 0,
- 0,
-
- 0,
- 0,
+static int kdf_hkdf_derive(EVP_KDF_IMPL *impl, unsigned char *key,
+ size_t keylen)
+{
+ if (impl->md == NULL) {
+ KDFerr(KDF_F_KDF_HKDF_DERIVE, KDF_R_MISSING_MESSAGE_DIGEST);
+ return 0;
+ }
+ if (impl->key == NULL) {
+ KDFerr(KDF_F_KDF_HKDF_DERIVE, KDF_R_MISSING_KEY);
+ return 0;
+ }
- 0, 0,
+ switch (impl->mode) {
+ case EVP_KDF_HKDF_MODE_EXTRACT_AND_EXPAND:
+ return HKDF(impl->md, impl->salt, impl->salt_len, impl->key,
+ impl->key_len, impl->info, impl->info_len, key,
+ keylen);
- 0, 0, 0, 0,
+ case EVP_KDF_HKDF_MODE_EXTRACT_ONLY:
+ return HKDF_Extract(impl->md, impl->salt, impl->salt_len, impl->key,
+ impl->key_len, key, keylen);
- 0, 0,
+ case EVP_KDF_HKDF_MODE_EXPAND_ONLY:
+ return HKDF_Expand(impl->md, impl->key, impl->key_len, impl->info,
+ impl->info_len, key, keylen);
- 0, 0,
+ default:
+ return 0;
+ }
+}
- 0,
- pkey_hkdf_derive,
- pkey_hkdf_ctrl,
- pkey_hkdf_ctrl_str
+const EVP_KDF hkdf_kdf_meth = {
+ EVP_KDF_HKDF,
+ kdf_hkdf_new,
+ kdf_hkdf_free,
+ kdf_hkdf_reset,
+ kdf_hkdf_ctrl,
+ kdf_hkdf_ctrl_str,
+ kdf_hkdf_size,
+ kdf_hkdf_derive
};
-static unsigned char *HKDF(const EVP_MD *evp_md,
- const unsigned char *salt, size_t salt_len,
- const unsigned char *key, size_t key_len,
- const unsigned char *info, size_t info_len,
- unsigned char *okm, size_t okm_len)
+/*
+ * Refer to "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)"
+ * Section 2 (https://tools.ietf.org/html/rfc5869#section-2) and
+ * "Cryptographic Extraction and Key Derivation: The HKDF Scheme"
+ * Section 4.2 (https://eprint.iacr.org/2010/264.pdf).
+ *
+ * From the paper:
+ * The scheme HKDF is specified as:
+ * HKDF(XTS, SKM, CTXinfo, L) = K(1) | K(2) | ... | K(t)
+ *
+ * where:
+ * SKM is source key material
+ * XTS is extractor salt (which may be null or constant)
+ * CTXinfo is context information (may be null)
+ * L is the number of key bits to be produced by KDF
+ * k is the output length in bits of the hash function used with HMAC
+ * t = ceil(L/k)
+ * the value K(t) is truncated to its first d = L mod k bits.
+ *
+ * From RFC 5869:
+ * 2.2. Step 1: Extract
+ * HKDF-Extract(salt, IKM) -> PRK
+ * 2.3. Step 2: Expand
+ * HKDF-Expand(PRK, info, L) -> OKM
+ */
+static int HKDF(const EVP_MD *evp_md,
+ const unsigned char *salt, size_t salt_len,
+ const unsigned char *ikm, size_t ikm_len,
+ const unsigned char *info, size_t info_len,
+ unsigned char *okm, size_t okm_len)
{
unsigned char prk[EVP_MAX_MD_SIZE];
+ int ret, sz;
size_t prk_len;
- if (!HKDF_Extract(evp_md, salt, salt_len, key, key_len, prk, &prk_len))
- return NULL;
+ sz = EVP_MD_size(evp_md);
+ if (sz < 0)
+ return 0;
+ prk_len = (size_t)sz;
+
+ /* Step 1: HKDF-Extract(salt, IKM) -> PRK */
+ if (!HKDF_Extract(evp_md, salt, salt_len, ikm, ikm_len, prk, prk_len))
+ return 0;
+
+ /* Step 2: HKDF-Expand(PRK, info, L) -> OKM */
+ ret = HKDF_Expand(evp_md, prk, prk_len, info, info_len, okm, okm_len);
+ OPENSSL_cleanse(prk, sizeof(prk));
- return HKDF_Expand(evp_md, prk, prk_len, info, info_len, okm, okm_len);
+ return ret;
}
-static unsigned char *HKDF_Extract(const EVP_MD *evp_md,
- const unsigned char *salt, size_t salt_len,
- const unsigned char *key, size_t key_len,
- unsigned char *prk, size_t *prk_len)
+/*
+ * Refer to "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)"
+ * Section 2.2 (https://tools.ietf.org/html/rfc5869#section-2.2).
+ *
+ * 2.2. Step 1: Extract
+ *
+ * HKDF-Extract(salt, IKM) -> PRK
+ *
+ * Options:
+ * Hash a hash function; HashLen denotes the length of the
+ * hash function output in octets
+ *
+ * Inputs:
+ * salt optional salt value (a non-secret random value);
+ * if not provided, it is set to a string of HashLen zeros.
+ * IKM input keying material
+ *
+ * Output:
+ * PRK a pseudorandom key (of HashLen octets)
+ *
+ * The output PRK is calculated as follows:
+ *
+ * PRK = HMAC-Hash(salt, IKM)
+ */
+static int HKDF_Extract(const EVP_MD *evp_md,
+ const unsigned char *salt, size_t salt_len,
+ const unsigned char *ikm, size_t ikm_len,
+ unsigned char *prk, size_t prk_len)
{
- unsigned int tmp_len;
-
- if (!HMAC(evp_md, salt, salt_len, key, key_len, prk, &tmp_len))
- return NULL;
+ int sz = EVP_MD_size(evp_md);
- *prk_len = tmp_len;
- return prk;
+ if (sz < 0)
+ return 0;
+ if (prk_len != (size_t)sz) {
+ KDFerr(KDF_F_HKDF_EXTRACT, KDF_R_WRONG_OUTPUT_BUFFER_SIZE);
+ return 0;
+ }
+ /* calc: PRK = HMAC-Hash(salt, IKM) */
+ return HMAC(evp_md, salt, salt_len, ikm, ikm_len, prk, NULL) != NULL;
}
-static unsigned char *HKDF_Expand(const EVP_MD *evp_md,
- const unsigned char *prk, size_t prk_len,
- const unsigned char *info, size_t info_len,
- unsigned char *okm, size_t okm_len)
+/*
+ * Refer to "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)"
+ * Section 2.3 (https://tools.ietf.org/html/rfc5869#section-2.3).
+ *
+ * 2.3. Step 2: Expand
+ *
+ * HKDF-Expand(PRK, info, L) -> OKM
+ *
+ * Options:
+ * Hash a hash function; HashLen denotes the length of the
+ * hash function output in octets
+ *
+ * Inputs:
+ * PRK a pseudorandom key of at least HashLen octets
+ * (usually, the output from the extract step)
+ * info optional context and application specific information
+ * (can be a zero-length string)
+ * L length of output keying material in octets
+ * (<= 255*HashLen)
+ *
+ * Output:
+ * OKM output keying material (of L octets)
+ *
+ * The output OKM is calculated as follows:
+ *
+ * N = ceil(L/HashLen)
+ * T = T(1) | T(2) | T(3) | ... | T(N)
+ * OKM = first L octets of T
+ *
+ * where:
+ * T(0) = empty string (zero length)
+ * T(1) = HMAC-Hash(PRK, T(0) | info | 0x01)
+ * T(2) = HMAC-Hash(PRK, T(1) | info | 0x02)
+ * T(3) = HMAC-Hash(PRK, T(2) | info | 0x03)
+ * ...
+ *
+ * (where the constant concatenated to the end of each T(n) is a
+ * single octet.)
+ */
+static int HKDF_Expand(const EVP_MD *evp_md,
+ const unsigned char *prk, size_t prk_len,
+ const unsigned char *info, size_t info_len,
+ unsigned char *okm, size_t okm_len)
{
HMAC_CTX *hmac;
-
+ int ret = 0, sz;
unsigned int i;
-
unsigned char prev[EVP_MAX_MD_SIZE];
+ size_t done_len = 0, dig_len, n;
- size_t done_len = 0, dig_len = EVP_MD_size(evp_md);
+ sz = EVP_MD_size(evp_md);
+ if (sz <= 0)
+ return 0;
+ dig_len = (size_t)sz;
- size_t n = okm_len / dig_len;
+ /* calc: N = ceil(L/HashLen) */
+ n = okm_len / dig_len;
if (okm_len % dig_len)
n++;
- if (n > 255)
- return NULL;
+ if (n > 255 || okm == NULL)
+ return 0;
if ((hmac = HMAC_CTX_new()) == NULL)
- return NULL;
+ return 0;
if (!HMAC_Init_ex(hmac, prk, prk_len, evp_md, NULL))
goto err;
size_t copy_len;
const unsigned char ctr = i;
+ /* calc: T(i) = HMAC-Hash(PRK, T(i - 1) | info | i) */
if (i > 1) {
if (!HMAC_Init_ex(hmac, NULL, 0, NULL, NULL))
goto err;
done_len += copy_len;
}
-
- HMAC_CTX_free(hmac);
- return okm;
+ ret = 1;
err:
+ OPENSSL_cleanse(prev, sizeof(prev));
HMAC_CTX_free(hmac);
- return NULL;
+ return ret;
}
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