hostapd/src/crypto/crypto_internal.c

/*
 * Crypto wrapper for internal crypto implementation
 * Copyright (c) 2006-2009, Jouni Malinen <j@w1.fi>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Alternatively, this software may be distributed under the terms of BSD
 * license.
 *
 * See README and COPYING for more details.
 */

#include "includes.h"

#include "common.h"
#include "crypto.h"
#include "sha1_i.h"
#include "md5_i.h"

struct crypto_hash {
	enum crypto_hash_alg alg;
	union {
		struct MD5Context md5;
		struct SHA1Context sha1;
	} u;
	u8 key[64];
	size_t key_len;
};


struct crypto_hash * crypto_hash_init(enum crypto_hash_alg alg, const u8 *key,
				      size_t key_len)
{
	struct crypto_hash *ctx;
	u8 k_pad[64];
	u8 tk[20];
	size_t i;

	ctx = os_zalloc(sizeof(*ctx));
	if (ctx == NULL)
		return NULL;

	ctx->alg = alg;

	switch (alg) {
	case CRYPTO_HASH_ALG_MD5:
		MD5Init(&ctx->u.md5);
		break;
	case CRYPTO_HASH_ALG_SHA1:
		SHA1Init(&ctx->u.sha1);
		break;
	case CRYPTO_HASH_ALG_HMAC_MD5:
		if (key_len > sizeof(k_pad)) {
			MD5Init(&ctx->u.md5);
			MD5Update(&ctx->u.md5, key, key_len);
			MD5Final(tk, &ctx->u.md5);
			key = tk;
			key_len = 16;
		}
		os_memcpy(ctx->key, key, key_len);
		ctx->key_len = key_len;

		os_memcpy(k_pad, key, key_len);
		os_memset(k_pad + key_len, 0, sizeof(k_pad) - key_len);
		for (i = 0; i < sizeof(k_pad); i++)
			k_pad[i] ^= 0x36;
		MD5Init(&ctx->u.md5);
		MD5Update(&ctx->u.md5, k_pad, sizeof(k_pad));
		break;
	case CRYPTO_HASH_ALG_HMAC_SHA1:
		if (key_len > sizeof(k_pad)) {
			SHA1Init(&ctx->u.sha1);
			SHA1Update(&ctx->u.sha1, key, key_len);
			SHA1Final(tk, &ctx->u.sha1);
			key = tk;
			key_len = 20;
		}
		os_memcpy(ctx->key, key, key_len);
		ctx->key_len = key_len;

		os_memcpy(k_pad, key, key_len);
		os_memset(k_pad + key_len, 0, sizeof(k_pad) - key_len);
		for (i = 0; i < sizeof(k_pad); i++)
			k_pad[i] ^= 0x36;
		SHA1Init(&ctx->u.sha1);
		SHA1Update(&ctx->u.sha1, k_pad, sizeof(k_pad));
		break;
	default:
		os_free(ctx);
		return NULL;
	}

	return ctx;
}


void crypto_hash_update(struct crypto_hash *ctx, const u8 *data, size_t len)
{
	if (ctx == NULL)
		return;

	switch (ctx->alg) {
	case CRYPTO_HASH_ALG_MD5:
	case CRYPTO_HASH_ALG_HMAC_MD5:
		MD5Update(&ctx->u.md5, data, len);
		break;
	case CRYPTO_HASH_ALG_SHA1:
	case CRYPTO_HASH_ALG_HMAC_SHA1:
		SHA1Update(&ctx->u.sha1, data, len);
		break;
	}
}


int crypto_hash_finish(struct crypto_hash *ctx, u8 *mac, size_t *len)
{
	u8 k_pad[64];
	size_t i;

	if (ctx == NULL)
		return -2;

	if (mac == NULL || len == NULL) {
		os_free(ctx);
		return 0;
	}

	switch (ctx->alg) {
	case CRYPTO_HASH_ALG_MD5:
		if (*len < 16) {
			*len = 16;
			os_free(ctx);
			return -1;
		}
		*len = 16;
		MD5Final(mac, &ctx->u.md5);
		break;
	case CRYPTO_HASH_ALG_SHA1:
		if (*len < 20) {
			*len = 20;
			os_free(ctx);
			return -1;
		}
		*len = 20;
		SHA1Final(mac, &ctx->u.sha1);
		break;
	case CRYPTO_HASH_ALG_HMAC_MD5:
		if (*len < 16) {
			*len = 16;
			os_free(ctx);
			return -1;
		}
		*len = 16;

		MD5Final(mac, &ctx->u.md5);

		os_memcpy(k_pad, ctx->key, ctx->key_len);
		os_memset(k_pad + ctx->key_len, 0,
			  sizeof(k_pad) - ctx->key_len);
		for (i = 0; i < sizeof(k_pad); i++)
			k_pad[i] ^= 0x5c;
		MD5Init(&ctx->u.md5);
		MD5Update(&ctx->u.md5, k_pad, sizeof(k_pad));
		MD5Update(&ctx->u.md5, mac, 16);
		MD5Final(mac, &ctx->u.md5);
		break;
	case CRYPTO_HASH_ALG_HMAC_SHA1:
		if (*len < 20) {
			*len = 20;
			os_free(ctx);
			return -1;
		}
		*len = 20;

		SHA1Final(mac, &ctx->u.sha1);

		os_memcpy(k_pad, ctx->key, ctx->key_len);
		os_memset(k_pad + ctx->key_len, 0,
			  sizeof(k_pad) - ctx->key_len);
		for (i = 0; i < sizeof(k_pad); i++)
			k_pad[i] ^= 0x5c;
		SHA1Init(&ctx->u.sha1);
		SHA1Update(&ctx->u.sha1, k_pad, sizeof(k_pad));
		SHA1Update(&ctx->u.sha1, mac, 20);
		SHA1Final(mac, &ctx->u.sha1);
		break;
	}

	os_free(ctx);

	return 0;
}


int crypto_global_init(void)
{
	return 0;
}


void crypto_global_deinit(void)
{
}