diff options
Diffstat (limited to 'providers/common/kdfs/hkdf.c')
| -rw-r--r-- | providers/common/kdfs/hkdf.c | 440 |
1 files changed, 440 insertions, 0 deletions
diff --git a/providers/common/kdfs/hkdf.c b/providers/common/kdfs/hkdf.c new file mode 100644 index 0000000000..33c74da86a --- /dev/null +++ b/providers/common/kdfs/hkdf.c @@ -0,0 +1,440 @@ +/* + * Copyright 2016-2018 The OpenSSL Project Authors. All Rights Reserved. + * + * 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/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 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; + unsigned char *key; + size_t key_len; + unsigned char info[HKDF_MAXBUF]; + size_t info_len; +}; + +static EVP_KDF_IMPL *kdf_hkdf_new(void) +{ + EVP_KDF_IMPL *impl; + + if ((impl = OPENSSL_zalloc(sizeof(*impl))) == NULL) + KDFerr(KDF_F_KDF_HKDF_NEW, ERR_R_MALLOC_FAILURE); + return impl; +} + +static void kdf_hkdf_free(EVP_KDF_IMPL *impl) +{ + kdf_hkdf_reset(impl); + OPENSSL_free(impl); +} + +static void kdf_hkdf_reset(EVP_KDF_IMPL *impl) +{ + 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 kdf_hkdf_ctrl(EVP_KDF_IMPL *impl, int cmd, va_list args) +{ + const unsigned char *p; + size_t len; + const EVP_MD *md; + + switch (cmd) { + case EVP_KDF_CTRL_SET_MD: + md = va_arg(args, const EVP_MD *); + if (md == NULL) + return 0; + + impl->md = md; + return 1; + + case EVP_KDF_CTRL_SET_HKDF_MODE: + impl->mode = va_arg(args, int); + return 1; + + 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; + + OPENSSL_free(impl->salt); + impl->salt = OPENSSL_memdup(p, len); + if (impl->salt == NULL) + return 0; + + impl->salt_len = len; + return 1; + + 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; + + impl->key_len = len; + return 1; + + case EVP_KDF_CTRL_RESET_HKDF_INFO: + OPENSSL_cleanse(impl->info, impl->info_len); + impl->info_len = 0; + return 1; + + 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 (len > (HKDF_MAXBUF - impl->info_len)) + return 0; + + memcpy(impl->info + impl->info_len, p, len); + impl->info_len += len; + return 1; + + default: + return -2; + } +} + +static int kdf_hkdf_ctrl_str(EVP_KDF_IMPL *impl, const char *type, + const char *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 kdf_str2ctrl(impl, kdf_hkdf_ctrl, EVP_KDF_CTRL_SET_SALT, value); + + if (strcmp(type, "hexsalt") == 0) + return kdf_hex2ctrl(impl, kdf_hkdf_ctrl, EVP_KDF_CTRL_SET_SALT, value); + + if (strcmp(type, "key") == 0) + return kdf_str2ctrl(impl, kdf_hkdf_ctrl, EVP_KDF_CTRL_SET_KEY, value); + + if (strcmp(type, "hexkey") == 0) + return kdf_hex2ctrl(impl, kdf_hkdf_ctrl, EVP_KDF_CTRL_SET_KEY, value); + + if (strcmp(type, "info") == 0) + return kdf_str2ctrl(impl, kdf_hkdf_ctrl, EVP_KDF_CTRL_ADD_HKDF_INFO, + value); + + if (strcmp(type, "hexinfo") == 0) + return kdf_hex2ctrl(impl, kdf_hkdf_ctrl, EVP_KDF_CTRL_ADD_HKDF_INFO, + value); + + return -2; +} + +static size_t kdf_hkdf_size(EVP_KDF_IMPL *impl) +{ + int sz; + + if (impl->mode != EVP_KDF_HKDF_MODE_EXTRACT_ONLY) + return SIZE_MAX; + + 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 sz; +} + +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; + } + + 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); + + case EVP_KDF_HKDF_MODE_EXTRACT_ONLY: + return HKDF_Extract(impl->md, impl->salt, impl->salt_len, impl->key, + impl->key_len, key, keylen); + + case EVP_KDF_HKDF_MODE_EXPAND_ONLY: + return HKDF_Expand(impl->md, impl->key, impl->key_len, impl->info, + impl->info_len, key, keylen); + + default: + return 0; + } +} + +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 +}; + +/* + * 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; + + 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 ret; +} + +/* + * 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) +{ + int sz = EVP_MD_size(evp_md); + + 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; +} + +/* + * 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; + + sz = EVP_MD_size(evp_md); + if (sz <= 0) + return 0; + dig_len = (size_t)sz; + + /* calc: N = ceil(L/HashLen) */ + n = okm_len / dig_len; + if (okm_len % dig_len) + n++; + + if (n > 255 || okm == NULL) + return 0; + + if ((hmac = HMAC_CTX_new()) == NULL) + return 0; + + 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; + + /* 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; + + 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; + } + ret = 1; + + err: + OPENSSL_cleanse(prev, sizeof(prev)); + HMAC_CTX_free(hmac); + return ret; +} |