293 lines
7.3 KiB
C
293 lines
7.3 KiB
C
/*
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* Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the OpenSSL license (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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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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