- implementation supporting SHA1
- UNtested
This commit is contained in:
Martin Willi
@@ -0,0 +1,212 @@
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/**
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* @file hmac.c
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*
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* @brief Implementation of message authentication
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* using cryptographic hash functions (HMAC). See RFC2104.
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*
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*/
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/*
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* Copyright (C) 2005 Jan Hutter, Martin Willi
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* Hochschule fuer Technik Rapperswil
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*/
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#include "hmac.h"
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#include "../utils/allocator.h"
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/**
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* Private data of an hmac_t object.
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*
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*/
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typedef struct private_hmac_s private_hmac_t;
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struct private_hmac_s {
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/**
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* public hmac_t interface
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*/
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hmac_t public;
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/**
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* key, as in RFC
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*/
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chunk_t k;
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/**
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* block size, as in RFC
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*/
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u_int8_t b;
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/**
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* hash function
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*/
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hasher_t *h;
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/**
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* previously xor'ed key using opad
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*/
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chunk_t opaded_key;
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/**
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* previously xor'ed key using ipad
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*/
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chunk_t ipaded_key;
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};
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/**
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* implementation of hmac_t.get_mac
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*/
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static status_t get_mac(private_hmac_t *this, chunk_t data, u_int8_t *out)
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{
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/* H(K XOR opad, H(K XOR ipad, text)) */
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u_int8_t buffer[this->h->get_block_size(this->h)];
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chunk_t inner;
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inner.ptr = buffer;
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inner.len = this->h->get_block_size(this->h);
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/* inner */
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this->h->get_hash(this->h, this->ipaded_key, NULL);
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this->h->get_hash(this->h, data, buffer);
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/* outer */
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this->h->get_hash(this->h, this->opaded_key, NULL);
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this->h->get_hash(this->h, inner, out);
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return SUCCESS;
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}
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/**
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* implementation of hmac_t.allocate_mac
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*/
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static status_t allocate_mac(private_hmac_t *this, chunk_t data, chunk_t *out)
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{
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/* allocate space and use get_mac */
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out->len = this->h->get_block_size(this->h);
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out->ptr = allocator_alloc(out->len);
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if (out->ptr == NULL)
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{
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return OUT_OF_RES;
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}
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this->public.get_mac(&(this->public), data, out->ptr);
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return SUCCESS;
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}
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/**
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* implementation of hmac_t.get_block_size
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*/
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static size_t get_block_size(private_hmac_t *this)
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{
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return this->h->get_block_size(this->h);
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}
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/**
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* implementation of hmac_t.destroy
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*/
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static status_t destroy(private_hmac_t *this)
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{
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this->h->destroy(this->h);
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allocator_free(this->k.ptr);
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allocator_free(this->opaded_key.ptr);
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allocator_free(this->ipaded_key.ptr);
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allocator_free(this);
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return SUCCESS;
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}
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/*
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* Described in header
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*/
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hmac_t *hmac_create(hash_algorithm_t hash_algorithm, chunk_t key)
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{
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private_hmac_t *this;
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u_int8_t i;
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this = allocator_alloc_thing(private_hmac_t);
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if (this == NULL)
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{
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return NULL;
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}
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/* set public methods */
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this->public.get_mac = (size_t (*)(hmac_t *,chunk_t,u_int8_t*))get_mac;
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this->public.allocate_mac = (size_t (*)(hmac_t *,chunk_t,chunk_t*))allocate_mac;
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this->public.get_block_size = (size_t (*)(hmac_t *))get_block_size;
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this->public.destroy = (status_t (*)(hmac_t *))destroy;
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/* set b, according to hasher */
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switch (hash_algorithm)
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{
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case HASH_SHA1:
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this->b = 64;
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break;
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default:
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allocator_free(this);
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return NULL;
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}
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/* build the hasher */
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this->h = hasher_create(hash_algorithm);
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if (this->h == NULL)
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{
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allocator_free(this);
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return NULL;
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}
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/* k must be b long, padded with 0x00 */
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this->k.ptr = allocator_alloc(this->b);
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this->k.len = this->b;
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if (this->k.ptr == NULL)
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{
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this->h->destroy(this->h);
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allocator_free(this);
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}
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memset(this->k.ptr, 0, this->k.len);
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if (key.len > this->h->get_block_size(this->h))
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{
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/* if key is too long, it will be hashed */
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this->h->get_hash(this->h, key, this->k.ptr);
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}
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else
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{
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/* if not, just copy it in our pre-padded k */
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memcpy(this->k.ptr, key.ptr, key.len);
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}
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/* build ipad and opad */
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this->opaded_key.ptr = allocator_alloc(this->b);
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this->opaded_key.len = this->b;
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if (this->opaded_key.ptr == NULL)
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{
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this->h->destroy(this->h);
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allocator_free(this->k.ptr);
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allocator_free(this);
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return NULL;
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}
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this->ipaded_key.ptr = allocator_alloc(this->b);
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this->ipaded_key.len = this->b;
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if (this->ipaded_key.ptr == NULL)
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{
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this->h->destroy(this->h);
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allocator_free(this->k.ptr);
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allocator_free(this->opaded_key.ptr);
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allocator_free(this);
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return NULL;
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}
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for (i = 0; i < this->b; i++)
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{
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this->ipaded_key.ptr[i] = this->k.ptr[i] ^ 0x36;
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this->opaded_key.ptr[i] = this->k.ptr[i] ^ 0x5C;
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}
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return &(this->public);
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}
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@@ -0,0 +1,90 @@
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/**
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* @file hmac.h
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*
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* @brief Implementation of message authentication
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* using cryptographic hash functions (HMAC). See RFC2104.
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*
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*/
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/*
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* Copyright (C) 2005 Jan Hutter, Martin Willi
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* Hochschule fuer Technik Rapperswil
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*/
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#ifndef HMAC_H_
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#define HMAC_H_
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#include "hashers/hasher.h"
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/**
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* Object representing a hmac
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*/
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typedef struct hmac_s hmac_t;
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struct hmac_s {
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/**
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* @brief Generate message authentication code.
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*
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* @param this calling hmac
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* @param data chunk of data to authenticate
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* @param [out]buffer pointer where the generated bytes will be written
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* @return
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* - SUCCESS in any case
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*/
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status_t (*get_mac) (hmac_t *this, chunk_t data, u_int8_t *buffer);
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/**
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* @brief Generates message authentication code and
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* allocate space for them.
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*
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* @param this calling hmac
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* @param data chunk of data to authenticate
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* @param [out]chunk chunk which will hold generated bytes
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* @return
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* - SUCCESS in any case
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* - OUT_OF_RES if space could not be allocated
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*/
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status_t (*allocate_mac) (hmac_t *this, chunk_t data, chunk_t *chunk);
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/**
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* @brief get the block size of this hmac
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*
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* @param this calling hmac
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* @return block size in bytes
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*/
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size_t (*get_block_size) (hmac_t *this);
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/**
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* @brief Destroys a hmac object.
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*
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* @param this hmac_t object to destroy
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* @return
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* SUCCESS in any case
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*/
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status_t (*destroy) (hmac_t *this);
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};
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/**
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* Creates a new hmac_t object
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*
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* @param hash_algorithm hash algorithm to use
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* @param key A chunk containing the key
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* @return
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* - hmac_t if successfully
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* - NULL if out of ressources or hash not supported
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*/
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hmac_t *hmac_create(hash_algorithm_t hash_algorithm, chunk_t key);
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#endif /*HMAC_H_*/
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