gnu_crypto.c

/*
Copyright (c) 2013 Eugene Crosser

This software is provided 'as-is', without any express or implied
warranty. In no event will the authors be held liable for any damages
arising from the use of this software.

Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:

    1. The origin of this software must not be misrepresented; you must
    not claim that you wrote the original software. If you use this
    software in a product, an acknowledgment in the product documentation
    would be appreciated but is not required.

    2. Altered source versions must be plainly marked as such, and must
    not be misrepresented as being the original software.

    3. This notice may not be removed or altered from any source
    distribution.
*/

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <errno.h>
#include <gcrypt.h>
#include "crypto_if.h"

static const char *gnu_init(void)
{
	(void)gcry_check_version(GCRYPT_VERSION);
	gcry_control(GCRYCTL_SUSPEND_SECMEM_WARN);
	gcry_control(GCRYCTL_INITIALIZATION_FINISHED, 0);
	return "gcrypt";
}

static unsigned long gnu_encrypt(const void *key, const size_t keylen, void *iv,
			const void *pt, void *ct, const size_t tlen)
{
	gcry_error_t err;
	gcry_cipher_hd_t hd;

	if ((err = gcry_cipher_open(&hd, GCRY_CIPHER_AES128,
					GCRY_CIPHER_MODE_CBC, 0)))
		return (unsigned long)err;
	if ((err = gcry_cipher_setkey(hd, key, keylen)))
		return (unsigned long)err;
	if ((err = gcry_cipher_setiv(hd, iv, keylen)))
		return (unsigned long)err;
	if ((err = gcry_cipher_encrypt(hd, ct, tlen, pt, tlen)))
		return (unsigned long)err;
	if ((err = gcry_cipher_reset(hd)))
		return (unsigned long)err;
	return 0UL;
}

static unsigned long gnu_decrypt(const void *key, const size_t keylen, void *iv,
			const void *ct, void *pt, const size_t tlen)
{
	gcry_error_t err;
	gcry_cipher_hd_t hd;

	if ((err = gcry_cipher_open(&hd, GCRY_CIPHER_AES128,
					GCRY_CIPHER_MODE_CBC, 0)))
		return (unsigned long)err;
	if ((err = gcry_cipher_setkey(hd, key, keylen)))
		return (unsigned long)err;
	if ((err = gcry_cipher_setiv(hd, iv, keylen)))
		return (unsigned long)err;
	if ((err = gcry_cipher_decrypt(hd, pt, tlen, ct, tlen)))
		return (unsigned long)err;
	if ((err = gcry_cipher_reset(hd)))
		return (unsigned long)err;
	return 0UL;
}

static unsigned long gnu_hash(const void *pt, const size_t tlen,
			void *tag, size_t *taglen)
{
	gcry_error_t err;
	gcry_md_hd_t hd;

	unsigned int dlen = gcry_md_get_algo_dlen(GCRY_MD_SHA1);
	if (*taglen < dlen)
		return (unsigned long)gcry_error_from_errno(ENOMEM);
	if ((err = gcry_md_open(&hd, GCRY_MD_SHA1, GCRY_MD_FLAG_SECURE)))
		return (unsigned long)err;
	gcry_md_write(hd, pt, tlen);
	gcry_md_final(hd);
	memcpy(tag, gcry_md_read(hd, GCRY_MD_SHA1), dlen);
	gcry_md_close(hd);
	*taglen = dlen;
	return 0UL;
}

static unsigned long gnu_hmac(const void *key, const size_t keylen,
			const void *pt, const size_t tlen,
			void *tag, size_t *taglen)
{
	gcry_error_t err;
	gcry_md_hd_t hd;

	unsigned int dlen = gcry_md_get_algo_dlen(GCRY_MD_SHA1);
	if (*taglen < dlen)
		return (unsigned long)gcry_error_from_errno(ENOMEM);
	if ((err = gcry_md_open(&hd, GCRY_MD_SHA1, GCRY_MD_FLAG_SECURE |
							GCRY_MD_FLAG_HMAC)))
		return (unsigned long)err;
	if ((err = gcry_md_setkey(hd, key, keylen)))
		return (unsigned long)err;
	gcry_md_write(hd, pt, tlen);
	gcry_md_final(hd);
	memcpy(tag, gcry_md_read(hd, GCRY_MD_SHA1), dlen);
	gcry_md_close(hd);
	*taglen = dlen;
	return 0UL;
}

static const char *gnu_errstr(const unsigned long err)
{
	return gcry_strerror((gcry_error_t)err);
}

struct crypto_interface gnu_crypto_if = {
	.init		= gnu_init,
	.encrypt	= gnu_encrypt,
	.decrypt	= gnu_decrypt,
	.hash		= gnu_hash,
	.hmac		= gnu_hmac,
	.errstr		= gnu_errstr,
};