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Diffstat (limited to 'Source/lib/crypto/hmac.c')
| -rw-r--r-- | Source/lib/crypto/hmac.c | 210 |
1 files changed, 210 insertions, 0 deletions
diff --git a/Source/lib/crypto/hmac.c b/Source/lib/crypto/hmac.c new file mode 100644 index 000000000..dc31af3eb --- /dev/null +++ b/Source/lib/crypto/hmac.c @@ -0,0 +1,210 @@ +/** + * @file hmac.c + * + * @brief Implementation of hmac_t. + */ + +/* + * Copyright (C) 2005 Jan Hutter, Martin Willi + * Hochschule fuer Technik Rapperswil + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General hmac License as published by the + * Free Software Foundation; either version 2 of the License, or (at your + * option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY + * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General hmac License + * for more details. + */ + + +#include "hmac.h" + +#include <utils/allocator.h> + + +typedef struct private_hmac_t private_hmac_t; + +/** + * Private data of a hmac_t object. + * + * The variable names are the same as in the RFC. + */ +struct private_hmac_t { + /** + * Public hmac_t interface. + */ + hmac_t hmac; + + /** + * Block size, as in RFC. + */ + u_int8_t b; + + /** + * Hash function. + */ + hasher_t *h; + + /** + * Previously xor'ed key using opad. + */ + chunk_t opaded_key; + + /** + * Previously xor'ed key using ipad. + */ + chunk_t ipaded_key; +}; + +/** + * Implementation of hmac_t.get_mac. + */ +static void get_mac(private_hmac_t *this, chunk_t data, u_int8_t *out) +{ + /* H(K XOR opad, H(K XOR ipad, text)) + * + * if out is NULL, we append text to the inner hash. + * else, we complete the inner and do the outer. + * + */ + + u_int8_t buffer[this->h->get_block_size(this->h)]; + chunk_t inner; + + if (out == NULL) + { + /* append data to inner */ + this->h->get_hash(this->h, data, NULL); + } + else + { + /* append and do outer hash */ + inner.ptr = buffer; + inner.len = this->h->get_block_size(this->h); + + /* complete inner */ + this->h->get_hash(this->h, data, buffer); + + /* do outer */ + this->h->get_hash(this->h, this->opaded_key, NULL); + this->h->get_hash(this->h, inner, out); + + /* reinit for next call */ + this->h->get_hash(this->h, this->ipaded_key, NULL); + } +} + +/** + * Implementation of hmac_t.allocate_mac. + */ +static void allocate_mac(private_hmac_t *this, chunk_t data, chunk_t *out) +{ + /* allocate space and use get_mac */ + if (out == NULL) + { + /* append mode */ + this->hmac.get_mac(&(this->hmac), data, NULL); + } + else + { + out->len = this->h->get_block_size(this->h); + out->ptr = allocator_alloc(out->len); + this->hmac.get_mac(&(this->hmac), data, out->ptr); + } +} + +/** + * Implementation of hmac_t.get_block_size. + */ +static size_t get_block_size(private_hmac_t *this) +{ + return this->h->get_block_size(this->h); +} + +/** + * Implementation of hmac_t.set_key. + */ +static void set_key(private_hmac_t *this, chunk_t key) +{ + int i; + u_int8_t buffer[this->b]; + + memset(buffer, 0, this->b); + + if (key.len > this->b) + { + /* if key is too long, it will be hashed */ + this->h->get_hash(this->h, key, buffer); + } + else + { + /* if not, just copy it in our pre-padded k */ + memcpy(buffer, key.ptr, key.len); + } + + /* apply ipad and opad to key */ + for (i = 0; i < this->b; i++) + { + this->ipaded_key.ptr[i] = buffer[i] ^ 0x36; + this->opaded_key.ptr[i] = buffer[i] ^ 0x5C; + } + + /* begin hashing of inner pad */ + this->h->reset(this->h); + this->h->get_hash(this->h, this->ipaded_key, NULL); +} + +/** + * Implementation of hmac_t.destroy. + */ +static void destroy(private_hmac_t *this) +{ + this->h->destroy(this->h); + allocator_free(this->opaded_key.ptr); + allocator_free(this->ipaded_key.ptr); + allocator_free(this); +} + +/* + * Described in header + */ +hmac_t *hmac_create(hash_algorithm_t hash_algorithm) +{ + private_hmac_t *this; + + this = allocator_alloc_thing(private_hmac_t); + + /* set hmac_t methods */ + this->hmac.get_mac = (void (*)(hmac_t *,chunk_t,u_int8_t*))get_mac; + this->hmac.allocate_mac = (void (*)(hmac_t *,chunk_t,chunk_t*))allocate_mac; + this->hmac.get_block_size = (size_t (*)(hmac_t *))get_block_size; + this->hmac.set_key = (void (*)(hmac_t *,chunk_t))set_key; + this->hmac.destroy = (void (*)(hmac_t *))destroy; + + /* set b, according to hasher */ + switch (hash_algorithm) + { + case HASH_SHA1: + case HASH_MD5: + this->b = 64; + break; + default: + allocator_free(this); + return NULL; + } + + /* build the hasher */ + this->h = hasher_create(hash_algorithm); + + /* build ipad and opad */ + this->opaded_key.ptr = allocator_alloc(this->b); + this->opaded_key.len = this->b; + + this->ipaded_key.ptr = allocator_alloc(this->b); + this->ipaded_key.len = this->b; + + return &(this->hmac); +} |