1 files changed, 173 insertions, 0 deletions
diff --git a/src/libstrongswan/plugins/ctr/ctr_ipsec_crypter.c b/src/libstrongswan/plugins/ctr/ctr_ipsec_crypter.c
new file mode 100644
index 000000000..ddcae423b
--- /dev/null
+++ b/src/libstrongswan/plugins/ctr/ctr_ipsec_crypter.c
@@ -0,0 +1,173 @@
+/*
+ * Copyright (C) 2010 Martin Willi
+ * Copyright (C) 2010 revosec AG
+ *
+ * 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 "ctr_ipsec_crypter.h"
+
+typedef struct private_ctr_ipsec_crypter_t private_ctr_ipsec_crypter_t;
+
+/**
+ * Private data of an ctr_ipsec_crypter_t object.
+ */
+struct private_ctr_ipsec_crypter_t {
+
+	/**
+	 * Public ctr_ipsec_crypter_t interface.
+	 */
+	ctr_ipsec_crypter_t public;
+
+	/**
+	 * Underlying CBC crypter
+	 */
+	crypter_t *crypter;
+
+	/**
+	 * counter state
+	 */
+	struct {
+		char nonce[4];
+		char iv[8];
+		u_int32_t counter;
+	} __attribute__((packed)) state;
+};
+
+/**
+ * Do the CTR crypto operation
+ */
+static void crypt_ctr(private_ctr_ipsec_crypter_t *this,
+					  chunk_t in, chunk_t out)
+{
+	size_t is, bs;
+	chunk_t state;
+
+	is = this->crypter->get_iv_size(this->crypter);
+	bs = sizeof(this->state);
+
+	this->state.counter = htonl(1);
+	state = chunk_create((char*)&this->state, bs);
+
+	while (in.len > 0)
+	{
+		char iv[is], block[bs];
+
+		memset(iv, 0, is);
+		memcpy(block, state.ptr, bs);
+		this->crypter->encrypt(this->crypter,
+						chunk_create(block, bs), chunk_create(iv, is), NULL);
+		chunk_increment(state);
+
+		if (in.ptr != out.ptr)
+		{
+			memcpy(out.ptr, in.ptr, min(in.len, bs));
+		}
+		memxor(out.ptr, block, min(in.len, bs));
+		in = chunk_skip(in, bs);
+		out = chunk_skip(out, bs);
+	}
+}
+
+METHOD(crypter_t, crypt, void,
+	private_ctr_ipsec_crypter_t *this, chunk_t in, chunk_t iv, chunk_t *out)
+{
+	memcpy(this->state.iv, iv.ptr, sizeof(this->state.iv));
+
+	if (out)
+	{
+		*out = chunk_alloc(in.len);
+		crypt_ctr(this, in, *out);
+	}
+	else
+	{
+		crypt_ctr(this, in, in);
+	}
+}
+
+METHOD(crypter_t, get_block_size, size_t,
+	private_ctr_ipsec_crypter_t *this)
+{
+	return 1;
+}
+
+METHOD(crypter_t, get_iv_size, size_t,
+	private_ctr_ipsec_crypter_t *this)
+{
+	return sizeof(this->state.iv);
+}
+
+METHOD(crypter_t, get_key_size, size_t,
+	private_ctr_ipsec_crypter_t *this)
+{
+	return this->crypter->get_key_size(this->crypter)
+			+ sizeof(this->state.nonce);
+}
+
+METHOD(crypter_t, set_key, void,
+	private_ctr_ipsec_crypter_t *this, chunk_t key)
+{
+	memcpy(this->state.nonce, key.ptr + key.len - sizeof(this->state.nonce),
+		   sizeof(this->state.nonce));
+	key.len -= sizeof(this->state.nonce);
+	this->crypter->set_key(this->crypter, key);
+}
+
+METHOD(crypter_t, destroy, void,
+	private_ctr_ipsec_crypter_t *this)
+{
+	this->crypter->destroy(this->crypter);
+	free(this);
+}
+
+/**
+ * See header
+ */
+ctr_ipsec_crypter_t *ctr_ipsec_crypter_create(encryption_algorithm_t algo,
+											  size_t key_size)
+{
+	private_ctr_ipsec_crypter_t *this;
+
+	switch (algo)
+	{
+		case ENCR_AES_CTR:
+			algo = ENCR_AES_CBC;
+			break;
+		case ENCR_CAMELLIA_CTR:
+			algo = ENCR_CAMELLIA_CBC;
+			break;
+		default:
+			return NULL;
+	}
+
+	INIT(this,
+		.public = {
+			.crypter = {
+				.encrypt = _crypt,
+				.decrypt = _crypt,
+				.get_block_size = _get_block_size,
+				.get_iv_size = _get_iv_size,
+				.get_key_size = _get_key_size,
+				.set_key = _set_key,
+				.destroy = _destroy,
+			},
+		},
+		.crypter = lib->crypto->create_crypter(lib->crypto, algo, key_size),
+	);
+
+	if (!this->crypter)
+	{
+		free(this);
+		return NULL;
+	}
+
+	return &this->public;
+}