diff options
Diffstat (limited to 'src/lib/hmac.c')
| -rw-r--r-- | src/lib/hmac.c | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/src/lib/hmac.c b/src/lib/hmac.c new file mode 100644 index 0000000..0138a4a --- /dev/null +++ b/src/lib/hmac.c @@ -0,0 +1,152 @@ +/* + * HMAC (RFC-2104) implementation. + * + * Copyright (c) 2004 Andrey Panin <pazke@donpac.ru> + * Copyright (c) 2011-2016 Florian Zeitz <florob@babelmonkeys.de> + * + * This software is released under the MIT license. + */ + +#include "lib.h" +#include "hmac.h" +#include "safe-memset.h" +#include "buffer.h" + +#include "hex-binary.h" + +void hmac_init(struct hmac_context *_ctx, const unsigned char *key, + size_t key_len, const struct hash_method *meth) +{ + struct hmac_context_priv *ctx = &_ctx->u.priv; + unsigned int i; + unsigned char k_ipad[meth->block_size]; + unsigned char k_opad[meth->block_size]; + unsigned char hashedkey[meth->digest_size]; + + i_assert(meth->context_size <= HMAC_MAX_CONTEXT_SIZE); + + ctx->hash = meth; + + if (key_len > meth->block_size) { + meth->init(ctx->ctx); + meth->loop(ctx->ctx, key, key_len); + meth->result(ctx->ctx, hashedkey); + key = hashedkey; + key_len = meth->digest_size; + } + + memcpy(k_ipad, key, key_len); + memset(k_ipad + key_len, 0, meth->block_size - key_len); + memcpy(k_opad, k_ipad, meth->block_size); + + for (i = 0; i < meth->block_size; i++) { + k_ipad[i] ^= 0x36; + k_opad[i] ^= 0x5c; + } + + meth->init(ctx->ctx); + meth->loop(ctx->ctx, k_ipad, meth->block_size); + meth->init(ctx->ctxo); + meth->loop(ctx->ctxo, k_opad, meth->block_size); + + safe_memset(k_ipad, 0, meth->block_size); + safe_memset(k_opad, 0, meth->block_size); +} + +void hmac_final(struct hmac_context *_ctx, unsigned char *digest) +{ + struct hmac_context_priv *ctx = &_ctx->u.priv; + + ctx->hash->result(ctx->ctx, digest); + + ctx->hash->loop(ctx->ctxo, digest, ctx->hash->digest_size); + ctx->hash->result(ctx->ctxo, digest); +} + +buffer_t *t_hmac_data(const struct hash_method *meth, + const unsigned char *key, size_t key_len, + const void *data, size_t data_len) +{ + struct hmac_context ctx; + i_assert(meth != NULL); + i_assert(key != NULL && key_len > 0); + i_assert(data != NULL || data_len == 0); + + buffer_t *res = t_buffer_create(meth->digest_size); + hmac_init(&ctx, key, key_len, meth); + if (data_len > 0) + hmac_update(&ctx, data, data_len); + unsigned char *buf = buffer_get_space_unsafe(res, 0, meth->digest_size); + hmac_final(&ctx, buf); + return res; +} + +buffer_t *t_hmac_buffer(const struct hash_method *meth, + const unsigned char *key, size_t key_len, + const buffer_t *data) +{ + return t_hmac_data(meth, key, key_len, data->data, data->used); +} + +buffer_t *t_hmac_str(const struct hash_method *meth, + const unsigned char *key, size_t key_len, + const char *data) +{ + return t_hmac_data(meth, key, key_len, data, strlen(data)); +} + +void hmac_hkdf(const struct hash_method *method, + const unsigned char *salt, size_t salt_len, + const unsigned char *ikm, size_t ikm_len, + const unsigned char *info, size_t info_len, + buffer_t *okm_r, size_t okm_len) +{ + i_assert(method != NULL); + i_assert(okm_len < 255*method->digest_size); + struct hmac_context key_mac; + struct hmac_context info_mac; + size_t remain = okm_len; + unsigned char prk[method->digest_size]; + unsigned char okm[method->digest_size]; + /* N = ceil(L/HashLen) */ + unsigned int rounds = (okm_len + method->digest_size - 1)/method->digest_size; + + /* salt and info can be NULL */ + i_assert(salt != NULL || salt_len == 0); + i_assert(info != NULL || info_len == 0); + + i_assert(ikm != NULL && ikm_len > 0); + i_assert(okm_r != NULL && okm_len > 0); + + /* but they still need valid pointer, reduces + complains from static analysers */ + if (salt == NULL) + salt = &uchar_nul; + if (info == NULL) + info = &uchar_nul; + + /* extract */ + hmac_init(&key_mac, salt, salt_len, method); + hmac_update(&key_mac, ikm, ikm_len); + hmac_final(&key_mac, prk); + + /* expand */ + for (unsigned int i = 0; remain > 0 && i < rounds; i++) { + unsigned char round = (i+1); + size_t amt = remain; + if (amt > method->digest_size) + amt = method->digest_size; + hmac_init(&info_mac, prk, method->digest_size, method); + if (i > 0) + hmac_update(&info_mac, okm, method->digest_size); + hmac_update(&info_mac, info, info_len); + hmac_update(&info_mac, &round, 1); + memset(okm, 0, method->digest_size); + hmac_final(&info_mac, okm); + buffer_append(okm_r, okm, amt); + remain -= amt; + } + + safe_memset(prk, 0, sizeof(prk)); + safe_memset(okm, 0, sizeof(okm)); +} |