Make the hmac_t interface a generic interface for message authentication codes

1 files changed, 220 insertions, 0 deletions

diff --git a/src/libstrongswan/plugins/hmac/hmac.c b/src/libstrongswan/plugins/hmac/hmac.c
new file mode 100644
index 000000000..ecfb01913
--- /dev/null
+++ b/src/libstrongswan/plugins/hmac/hmac.c
@@ -0,0 +1,220 @@
+/*
+ * Copyright (C) 2012 Tobias Brunner
+ * Copyright (C) 2005-2006 Martin Willi
+ * Copyright (C) 2005 Jan Hutter
+ * Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public 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 Public License
+ * for more details.
+ */
+
+#include "hmac.h"
+
+#include <crypto/mac.h>
+#include <crypto/prfs/mac_prf.h>
+#include <crypto/signers/mac_signer.h>
+
+typedef struct private_mac_t private_mac_t;
+
+/**
+ * Private data of a mac_t object.
+ *
+ * The variable names are the same as in the RFC.
+ */
+struct private_mac_t {
+
+	/**
+	 * Implements mac_t interface
+	 */
+	mac_t public;
+
+	/**
+	 * 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;
+};
+
+METHOD(mac_t, get_mac, void,
+	private_mac_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_hash_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_hash_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);
+	}
+}
+
+METHOD(mac_t, get_mac_size, size_t,
+	private_mac_t *this)
+{
+	return this->h->get_hash_size(this->h);
+}
+
+METHOD(mac_t, set_key, void,
+	private_mac_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);
+}
+
+METHOD(mac_t, destroy, void,
+	private_mac_t *this)
+{
+	this->h->destroy(this->h);
+	chunk_clear(&this->opaded_key);
+	chunk_clear(&this->ipaded_key);
+	free(this);
+}
+
+/*
+ * Creates an mac_t object
+ */
+static mac_t *hmac_create(hash_algorithm_t hash_algorithm)
+{
+	private_mac_t *this;
+
+	INIT(this,
+		.public = {
+			.get_mac = _get_mac,
+			.get_mac_size = _get_mac_size,
+			.set_key = _set_key,
+			.destroy = _destroy,
+		},
+	);
+
+	/* set b, according to hasher */
+	switch (hash_algorithm)
+	{
+		case HASH_SHA1:
+		case HASH_MD5:
+		case HASH_SHA256:
+			this->b = 64;
+			break;
+		case HASH_SHA384:
+		case HASH_SHA512:
+			this->b = 128;
+			break;
+		default:
+			free(this);
+			return NULL;
+	}
+
+	this->h = lib->crypto->create_hasher(lib->crypto, hash_algorithm);
+	if (this->h == NULL)
+	{
+		free(this);
+		return NULL;
+	}
+
+	/* build ipad and opad */
+	this->opaded_key.ptr = malloc(this->b);
+	this->opaded_key.len = this->b;
+
+	this->ipaded_key.ptr = malloc(this->b);
+	this->ipaded_key.len = this->b;
+
+	return &this->public;
+}
+
+/*
+ * Described in header
+ */
+prf_t *hmac_prf_create(pseudo_random_function_t algo)
+{
+	mac_t *hmac;
+
+	hmac = hmac_create(hasher_algorithm_from_prf(algo));
+	if (hmac)
+	{
+		return mac_prf_create(hmac);
+	}
+	return NULL;
+}
+
+/*
+ * Described in header
+ */
+signer_t *hmac_signer_create(integrity_algorithm_t algo)
+{
+	mac_t *hmac;
+	size_t trunc;
+
+	hmac = hmac_create(hasher_algorithm_from_integrity(algo, &trunc));
+	if (hmac)
+	{
+		return mac_signer_create(hmac, trunc);
+	}
+	return NULL;
+}