/* * Copyright 2016 The OpenSSL Project Authors. All Rights Reserved. * * Licensed under the OpenSSL license (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 #include #include #include #include #include "internal/cryptlib.h" #include "internal/evp_int.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 { const EVP_MD *md; unsigned char *salt; size_t salt_len; unsigned char *key; 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) { HKDF_PKEY_CTX *kctx; kctx = OPENSSL_zalloc(sizeof(*kctx)); if (kctx == NULL) return 0; ctx->data = kctx; return 1; } static void pkey_hkdf_cleanup(EVP_PKEY_CTX *ctx) { 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); } static int pkey_hkdf_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2) { HKDF_PKEY_CTX *kctx = ctx->data; switch (type) { case EVP_PKEY_CTRL_HKDF_MD: if (p2 == NULL) return 0; kctx->md = p2; return 1; case EVP_PKEY_CTRL_HKDF_SALT: if (p1 == 0 || p2 == NULL) return 1; if (p1 < 0) return 0; if (kctx->salt != NULL) OPENSSL_clear_free(kctx->salt, kctx->salt_len); kctx->salt = OPENSSL_memdup(p2, p1); if (kctx->salt == NULL) return 0; kctx->salt_len = p1; return 1; case EVP_PKEY_CTRL_HKDF_KEY: if (p1 < 0) 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; kctx->key_len = p1; return 1; case EVP_PKEY_CTRL_HKDF_INFO: if (p1 == 0 || p2 == NULL) return 1; if (p1 < 0 || p1 > (int)(HKDF_MAXBUF - kctx->info_len)) return 0; memcpy(kctx->info + kctx->info_len, p2, p1); kctx->info_len += p1; return 1; default: return -2; } } static int pkey_hkdf_ctrl_str(EVP_PKEY_CTX *ctx, 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, "salt") == 0) return EVP_PKEY_CTX_str2ctrl(ctx, EVP_PKEY_CTRL_HKDF_SALT, value); if (strcmp(type, "hexsalt") == 0) return EVP_PKEY_CTX_hex2ctrl(ctx, EVP_PKEY_CTRL_HKDF_SALT, value); if (strcmp(type, "key") == 0) return EVP_PKEY_CTX_str2ctrl(ctx, EVP_PKEY_CTRL_HKDF_KEY, value); if (strcmp(type, "hexkey") == 0) return EVP_PKEY_CTX_hex2ctrl(ctx, EVP_PKEY_CTRL_HKDF_KEY, value); if (strcmp(type, "info") == 0) return EVP_PKEY_CTX_str2ctrl(ctx, EVP_PKEY_CTRL_HKDF_INFO, value); if (strcmp(type, "hexinfo") == 0) return EVP_PKEY_CTX_hex2ctrl(ctx, EVP_PKEY_CTRL_HKDF_INFO, value); return -2; } static int pkey_hkdf_derive(EVP_PKEY_CTX *ctx, unsigned char *key, size_t *keylen) { HKDF_PKEY_CTX *kctx = ctx->data; if (kctx->md == NULL || kctx->key == NULL) return 0; if (HKDF(kctx->md, kctx->salt, kctx->salt_len, kctx->key, kctx->key_len, kctx->info, kctx->info_len, key, *keylen) == NULL) { return 0; } return 1; } 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, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, pkey_hkdf_derive, pkey_hkdf_ctrl, pkey_hkdf_ctrl_str }; 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) { unsigned char prk[EVP_MAX_MD_SIZE]; size_t prk_len; if (!HKDF_Extract(evp_md, salt, salt_len, key, key_len, prk, &prk_len)) return NULL; return HKDF_Expand(evp_md, prk, prk_len, info, info_len, okm, 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) { unsigned int tmp_len; if (!HMAC(evp_md, salt, salt_len, key, key_len, prk, &tmp_len)) return NULL; *prk_len = tmp_len; return prk; } 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) { HMAC_CTX *hmac; unsigned int i; unsigned char prev[EVP_MAX_MD_SIZE]; size_t done_len = 0, dig_len = EVP_MD_size(evp_md); size_t n = okm_len / dig_len; if (okm_len % dig_len) n++; if (n > 255) return NULL; if ((hmac = HMAC_CTX_new()) == NULL) return NULL; if (!HMAC_Init_ex(hmac, prk, prk_len, evp_md, NULL)) goto err; for (i = 1; i <= n; i++) { size_t copy_len; const unsigned char ctr = i; if (i > 1) { if (!HMAC_Init_ex(hmac, NULL, 0, NULL, NULL)) goto err; if (!HMAC_Update(hmac, prev, dig_len)) goto err; } if (!HMAC_Update(hmac, info, info_len)) goto err; if (!HMAC_Update(hmac, &ctr, 1)) goto err; if (!HMAC_Final(hmac, prev, NULL)) goto err; copy_len = (done_len + dig_len > okm_len) ? okm_len - done_len : dig_len; memcpy(okm + done_len, prev, copy_len); done_len += copy_len; } HMAC_CTX_free(hmac); return okm; err: HMAC_CTX_free(hmac); return NULL; }