This patch implements the HMAC-based Extract-and-Expand Key Derivation Function (HKDF) as defined in RFC 5869. It is required to implement the QUIC and TLS 1.3 protocols (among others). Signed-off-by: Rich Salz <rsalz@openssl.org> Reviewed-by: Dr. Stephen Henson <steve@openssl.org>master
Alessandro Ghedini
7 years ago
committed by
Rich Salz
parent
b894054e3f
commit
aacfb134be
@ -1,3 +1,3 @@
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LIBS=../../libcrypto
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SOURCE[../../libcrypto]=\
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tls1_prf.c kdf_err.c
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tls1_prf.c kdf_err.c hkdf.c
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@ -0,0 +1,332 @@
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/* ====================================================================
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* Copyright (c) 2016 The OpenSSL Project. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* 3. All advertising materials mentioning features or use of this
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* software must display the following acknowledgment:
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* "This product includes software developed by the OpenSSL Project
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* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
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*
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* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
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* endorse or promote products derived from this software without
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* prior written permission. For written permission, please contact
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* openssl-core@openssl.org.
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*
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* 5. Products derived from this software may not be called "OpenSSL"
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* nor may "OpenSSL" appear in their names without prior written
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* permission of the OpenSSL Project.
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*
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* 6. Redistributions of any form whatsoever must retain the following
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* acknowledgment:
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* "This product includes software developed by the OpenSSL Project
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* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
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*
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* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
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* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
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* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <stdlib.h>
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#include <string.h>
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#include <openssl/hmac.h>
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#include <openssl/kdf.h>
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#include <openssl/evp.h>
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#include "internal/cryptlib.h"
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#include "internal/evp_int.h"
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#define HKDF_MAXBUF 1024
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static unsigned char *HKDF(const EVP_MD *evp_md,
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const unsigned char *salt, size_t salt_len,
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const unsigned char *key, size_t key_len,
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const unsigned char *info, size_t info_len,
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unsigned char *okm, size_t okm_len);
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static unsigned char *HKDF_Extract(const EVP_MD *evp_md,
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const unsigned char *salt, size_t salt_len,
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const unsigned char *key, size_t key_len,
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unsigned char *prk, size_t *prk_len);
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static unsigned char *HKDF_Expand(const EVP_MD *evp_md,
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const unsigned char *prk, size_t prk_len,
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const unsigned char *info, size_t info_len,
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unsigned char *okm, size_t okm_len);
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typedef struct {
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const EVP_MD *md;
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unsigned char *salt;
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size_t salt_len;
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unsigned char *key;
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size_t key_len;
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unsigned char info[HKDF_MAXBUF];
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size_t info_len;
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} HKDF_PKEY_CTX;
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static int pkey_hkdf_init(EVP_PKEY_CTX *ctx)
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{
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HKDF_PKEY_CTX *kctx;
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kctx = OPENSSL_zalloc(sizeof(*kctx));
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if (kctx == NULL)
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return 0;
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ctx->data = kctx;
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return 1;
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}
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static void pkey_hkdf_cleanup(EVP_PKEY_CTX *ctx)
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{
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HKDF_PKEY_CTX *kctx = ctx->data;
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OPENSSL_clear_free(kctx->salt, kctx->salt_len);
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OPENSSL_clear_free(kctx->key, kctx->key_len);
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OPENSSL_cleanse(kctx->info, kctx->info_len);
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OPENSSL_free(kctx);
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}
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static int pkey_hkdf_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
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{
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HKDF_PKEY_CTX *kctx = ctx->data;
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switch (type) {
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case EVP_PKEY_CTRL_HKDF_MD:
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if (p2 == NULL)
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return 0;
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kctx->md = p2;
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return 1;
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case EVP_PKEY_CTRL_HKDF_SALT:
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if (p1 == 0 || p2 == NULL)
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return 1;
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if (p1 < 0)
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return 0;
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if (kctx->salt != NULL)
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OPENSSL_clear_free(kctx->salt, kctx->salt_len);
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kctx->salt = OPENSSL_memdup(p2, p1);
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if (kctx->salt == NULL)
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return 0;
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kctx->salt_len = p1;
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return 1;
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case EVP_PKEY_CTRL_HKDF_KEY:
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if (p1 < 0)
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return 0;
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if (kctx->key != NULL)
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OPENSSL_clear_free(kctx->key, kctx->key_len);
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kctx->key = OPENSSL_memdup(p2, p1);
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if (kctx->key == NULL)
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return 0;
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kctx->key_len = p1;
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return 1;
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case EVP_PKEY_CTRL_HKDF_INFO:
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if (p1 == 0 || p2 == NULL)
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return 1;
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if (p1 < 0 || p1 > (int)(HKDF_MAXBUF - kctx->info_len))
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return 0;
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memcpy(kctx->info + kctx->info_len, p2, p1);
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kctx->info_len += p1;
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return 1;
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default:
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return -2;
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}
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}
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static int pkey_hkdf_ctrl_str(EVP_PKEY_CTX *ctx, const char *type,
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const char *value)
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{
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if (strcmp(type, "md") == 0)
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return EVP_PKEY_CTX_set_hkdf_md(ctx, EVP_get_digestbyname(value));
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if (strcmp(type, "salt") == 0)
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return EVP_PKEY_CTX_str2ctrl(ctx, EVP_PKEY_CTRL_HKDF_SALT, value);
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if (strcmp(type, "hexsalt") == 0)
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return EVP_PKEY_CTX_hex2ctrl(ctx, EVP_PKEY_CTRL_HKDF_SALT, value);
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if (strcmp(type, "key") == 0)
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return EVP_PKEY_CTX_str2ctrl(ctx, EVP_PKEY_CTRL_HKDF_KEY, value);
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if (strcmp(type, "hexkey") == 0)
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return EVP_PKEY_CTX_hex2ctrl(ctx, EVP_PKEY_CTRL_HKDF_KEY, value);
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if (strcmp(type, "info") == 0)
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return EVP_PKEY_CTX_str2ctrl(ctx, EVP_PKEY_CTRL_HKDF_INFO, value);
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if (strcmp(type, "hexinfo") == 0)
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return EVP_PKEY_CTX_hex2ctrl(ctx, EVP_PKEY_CTRL_HKDF_INFO, value);
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return -2;
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}
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static int pkey_hkdf_derive(EVP_PKEY_CTX *ctx, unsigned char *key,
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size_t *keylen)
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{
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HKDF_PKEY_CTX *kctx = ctx->data;
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if (kctx->md == NULL || kctx->key == NULL)
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return 0;
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if (HKDF(kctx->md, kctx->salt, kctx->salt_len, kctx->key, kctx->key_len,
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kctx->info, kctx->info_len, key, *keylen) == NULL)
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{
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return 0;
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}
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return 1;
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}
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const EVP_PKEY_METHOD hkdf_pkey_meth = {
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EVP_PKEY_HKDF,
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0,
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pkey_hkdf_init,
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0,
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pkey_hkdf_cleanup,
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0, 0,
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0, 0,
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0,
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0,
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0,
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0,
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0, 0,
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0, 0, 0, 0,
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0, 0,
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0, 0,
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0,
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pkey_hkdf_derive,
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pkey_hkdf_ctrl,
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pkey_hkdf_ctrl_str
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};
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static unsigned char *HKDF(const EVP_MD *evp_md,
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const unsigned char *salt, size_t salt_len,
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const unsigned char *key, size_t key_len,
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const unsigned char *info, size_t info_len,
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unsigned char *okm, size_t okm_len)
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{
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unsigned char prk[EVP_MAX_MD_SIZE];
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size_t prk_len;
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if (!HKDF_Extract(evp_md, salt, salt_len, key, key_len, prk, &prk_len))
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return NULL;
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return HKDF_Expand(evp_md, prk, prk_len, info, info_len, okm, okm_len);
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}
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static unsigned char *HKDF_Extract(const EVP_MD *evp_md,
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const unsigned char *salt, size_t salt_len,
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const unsigned char *key, size_t key_len,
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unsigned char *prk, size_t *prk_len)
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{
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unsigned int tmp_len;
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if (!HMAC(evp_md, salt, salt_len, key, key_len, prk, &tmp_len))
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return NULL;
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*prk_len = tmp_len;
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return prk;
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}
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static unsigned char *HKDF_Expand(const EVP_MD *evp_md,
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const unsigned char *prk, size_t prk_len,
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const unsigned char *info, size_t info_len,
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unsigned char *okm, size_t okm_len)
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{
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HMAC_CTX *hmac;
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unsigned int i;
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unsigned char prev[EVP_MAX_MD_SIZE];
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size_t done_len = 0, dig_len = EVP_MD_size(evp_md);
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size_t n = okm_len / dig_len;
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if (okm_len % dig_len)
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n++;
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if (n > 255)
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return NULL;
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if ((hmac = HMAC_CTX_new()) == NULL)
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return NULL;
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if (!HMAC_Init_ex(hmac, prk, prk_len, evp_md, NULL))
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goto err;
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for (i = 1; i <= n; i++) {
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size_t copy_len;
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const unsigned char ctr = i;
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if (i > 1) {
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if (!HMAC_Init_ex(hmac, NULL, 0, NULL, NULL))
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goto err;
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if (!HMAC_Update(hmac, prev, dig_len))
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goto err;
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}
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if (!HMAC_Update(hmac, info, info_len))
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goto err;
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if (!HMAC_Update(hmac, &ctr, 1))
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goto err;
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if (!HMAC_Final(hmac, prev, NULL))
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goto err;
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copy_len = (done_len + dig_len > okm_len) ?
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okm_len - done_len :
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dig_len;
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memcpy(okm + done_len, prev, copy_len);
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done_len += copy_len;
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}
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HMAC_CTX_free(hmac);
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return okm;
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err:
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HMAC_CTX_free(hmac);
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return NULL;
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}
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@ -0,0 +1,103 @@
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=pod
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=head1 NAME
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EVP_PKEY_HKDF; EVP_PKEY_CTX_set_hkdf_md, EVP_PKEY_CTX_set1_hkdf_salt,
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EVP_PKEY_CTX_set1_hkdf_key, EVP_PKEY_CTX_add1_hkdf_info -
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HMAC-based Extract-and-Expand key derivation algorithm
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=head1 SYNOPSIS
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#include <openssl/kdf.h>
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int EVP_PKEY_CTX_set_hkdf_md(EVP_PKEY_CTX *pctx, const EVP_MD *md);
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int EVP_PKEY_CTX_set1_hkdf_salt(EVP_PKEY_CTX *pctx, unsigned char *salt,
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int saltlen);
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int EVP_PKEY_CTX_set1_hkdf_key(EVP_PKEY_CTX *pctx, unsigned char *key,
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int keylen);
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int EVP_PKEY_CTX_add1_hkdf_info(EVP_PKEY_CTX *pctx, unsigned char *info,
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int infolen);
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=head1 DESCRIPTION
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The EVP_PKEY_HKDF alogorithm implements the HKDF key derivation function.
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HKDF follows the "extract-then-expand" paradigm, where the KDF logically
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consists of two modules. The first stage takes the input keying material
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and "extracts" from it a fixed-length pseudorandom key K. The second stage
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"expands" the key K into several additional pseudorandom keys (the output
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of the KDF).
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EVP_PKEY_set_hkdf_md() sets the message digest associated with the HKDF.
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EVP_PKEY_CTX_set1_hkdf_salt() sets the salt to B<saltlen> bytes of the
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buffer B<salt>. Any existing value is replaced.
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EVP_PKEY_CTX_set_hkdf_key() sets the key to B<keylen> bytes of the buffer
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B<key>. Any existing value is replaced.
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EVP_PKEY_CTX_add1_hkdf_info() sets the info value to B<infolen> bytes of the
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buffer B<info>. If a value is already set, it is appended to the existing
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value.
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=head1 NOTES
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All these functions are implemented as macros.
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A context for HKDF can be obtained by calling:
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EVP_PKEY_CTX *pctx = EVP_PKEY_new_id(EVP_PKEY_HKDF, NULL);
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The digest, key, salt and info values must be set before a key is derived or
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an error occurs.
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The total length of the info buffer cannot exceed 1024 bytes in length: this
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should be more than enough for any normal use of HKDF.
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The output length of the KDF is specified by the length parameter in the
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EVP_PKEY_derive() function. Since the output length is variable, setting
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the buffer to B<NULL> is not meaningful for HKDF.
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Optimised versions of HKDF can be implemented in an ENGINE.
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=head1 RETURN VALUES
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All these functions return 1 for success and 0 or a negative value for failure.
|
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In particular a return value of -2 indicates the operation is not supported by
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the public key algorithm.
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=head1 EXAMPLE
|
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|
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This example derives 10 bytes using SHA-256 with the secret key "secret",
|
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salt value "salt" and info value "label":
|
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|
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EVP_PKEY_CTX *pctx;
|
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unsigned char out[10];
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size_t outlen = sizeof(out);
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pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_HKDF, NULL);
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|
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if (EVP_PKEY_derive_init(pctx) <= 0)
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/* Error */
|
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if (EVP_PKEY_CTX_set_hkdf_md(pctx, EVP_sha256()) <= 0)
|
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/* Error */
|
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if (EVP_PKEY_CTX_set1_salt(pctx, "salt", 4) <= 0)
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/* Error */
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if (EVP_PKEY_CTX_set1_key(pctx, "secret", 6) <= 0)
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/* Error */
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if (EVP_PKEY_CTX_add1_hkdf_info(pctx, "label", 6) <= 0)
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/* Error */
|
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if (EVP_PKEY_derive(pctx, out, &outlen) <= 0)
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/* Error */
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=head1 CONFORMING TO
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|
||||
RFC 5869
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|
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=head1 SEE ALSO
|
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|
||||
L<EVP_PKEY_CTX_new(3)>,
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L<EVP_PKEY_derive(3)>,
|
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|
||||
=cut
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Loading…
Reference in new issue