>From 36edee2012055747ddc23c108e4a57cede63c27c Mon Sep 17 00:00:00 2001
From: Ben Sartor <address@hidden>
Date: Tue, 6 Jan 2015 04:03:08 +0100
Subject: [PATCH 2/2] added cipher algorithm AES with 256-bit keys (AES3)

---
 include/cryptoWrapper.h | 34 ++++++++++++++++++++++++++
 src/cryptoPolarssl.c    | 63 +++++++++++++++++++++++++++++++++++++++++++++++--
 src/cryptoUtils.c       |  5 ++++
 3 files changed, 100 insertions(+), 2 deletions(-)

diff --git a/include/cryptoWrapper.h b/include/cryptoWrapper.h
index f02afb1..7e713c4 100644
--- a/include/cryptoWrapper.h
+++ b/include/cryptoWrapper.h
@@ -208,6 +208,40 @@ void bzrtpCrypto_aes128CfbDecrypt(const uint8_t *key,
 		uint8_t *output);
 
 /**
+ * @brief Wrapper for AES-256 in CFB128 mode encryption
+ * The key must be 32 bytes long and the IV must be 16 bytes long
+ *
+ * @param[in]	key			encryption key, 256 bits long
+ * @param[in]	IV			Initialisation vector, 128 bits long, is not modified by this function.
+ * @param[in]	input		Input data buffer
+ * @param[in]	inputLength	Input data length
+ * @param[out]	output		Output data buffer
+ *
+ */
+void bzrtpCrypto_aes256CfbEncrypt(const uint8_t *key,
+		const uint8_t *IV,
+		const uint8_t *input,
+		size_t inputLength,
+		uint8_t *output);
+
+/**
+ * @brief Wrapper for AES-256 in CFB128 mode decryption
+ * The key must be 32 bytes long and the IV must be 16 bytes long
+ *
+ * @param[in]	key			decryption key, 256 bits long
+ * @param[in]	IV			Initialisation vector, 128 bits long, is not modified by this function.
+ * @param[in]	input		Input data buffer
+ * @param[in]	inputLength	Input data length
+ * @param[out]	output		Output data buffer
+ *
+ */
+void bzrtpCrypto_aes256CfbDecrypt(const uint8_t *key,
+		const uint8_t *IV,
+		const uint8_t *input,
+		size_t inputLength,
+		uint8_t *output);
+
+/**
  * @brief Context for the Diffie-Hellman-Merkle key exchange
  *	ZRTP specifies the use of RFC3526 values for G and P so we do not need to store them in this context
  */
diff --git a/src/cryptoPolarssl.c b/src/cryptoPolarssl.c
index 486971a..e279d80 100644
--- a/src/cryptoPolarssl.c
+++ b/src/cryptoPolarssl.c
@@ -57,8 +57,9 @@ uint8_t bzrtpCrypto_getAvailableCryptoTypes(uint8_t algoType, uint8_t availableT
 			return 1;
 			break;
 		case ZRTP_CIPHERBLOCK_TYPE:
-			availableTypes[0] = ZRTP_CIPHER_AES1;
-			return 1;
+			availableTypes[0] = ZRTP_CIPHER_AES3;
+			availableTypes[1] = ZRTP_CIPHER_AES1;
+			return 2;
 			break;
 		case ZRTP_AUTHTAG_TYPE:
 			availableTypes[0] = ZRTP_AUTHTAG_HS32;
@@ -300,6 +301,64 @@ void bzrtpCrypto_aes128CfbDecrypt(const uint8_t key[16],
 	aes_crypt_cfb128 (&context, AES_DECRYPT, inputLength, &iv_offset, IVbuffer, input, output);
 }
 
+/*
+ * @brief Wrapper for AES-256 in CFB128 mode encryption
+ * The key must be 32 bytes long and the IV must be 16 bytes long, IV is not updated
+ *
+ * @param[in]	key			encryption key, 256 bits long
+ * @param[in]	IV			Initialisation vector, 128 bits long, is not modified by this function.
+ * @param[in]	input		Input data buffer
+ * @param[in]	inputLength	Input data length
+ * @param[out]	output		Output data buffer
+ *
+ */
+void bzrtpCrypto_aes256CfbEncrypt(const uint8_t key[32],
+		const uint8_t IV[16],
+		const uint8_t *input,
+		size_t inputLength,
+		uint8_t *output)
+{
+	uint8_t IVbuffer[16];
+	size_t iv_offset=0;
+	aes_context context;
+
+	memcpy(IVbuffer, IV, 16*sizeof(uint8_t));
+	memset (&context, 0, sizeof(aes_context));
+	aes_setkey_enc(&context, key, 256);
+
+	/* encrypt */
+	aes_crypt_cfb128 (&context, AES_ENCRYPT, inputLength, &iv_offset, IVbuffer, input, output);
+}
+
+/*
+ * @brief Wrapper for AES-256 in CFB128 mode decryption
+ * The key must be 32 bytes long and the IV must be 16 bytes long, IV is not updated
+ *
+ * @param[in]	key			decryption key, 256 bits long
+ * @param[in]	IV			Initialisation vector, 128 bits long, is not modified by this function.
+ * @param[in]	input		Input data buffer
+ * @param[in]	inputLength	Input data length
+ * @param[out]	output		Output data buffer
+ *
+ */
+void bzrtpCrypto_aes256CfbDecrypt(const uint8_t key[32],
+		const uint8_t IV[16],
+		const uint8_t *input,
+		size_t inputLength,
+		uint8_t *output)
+{
+	uint8_t IVbuffer[16];
+	size_t iv_offset=0;
+	aes_context context;
+
+	memcpy(IVbuffer, IV, 16*sizeof(uint8_t));
+	memset (&context, 0, sizeof(aes_context));
+	aes_setkey_enc(&context, key, 256);
+
+	/* decrypt */
+	aes_crypt_cfb128 (&context, AES_DECRYPT, inputLength, &iv_offset, IVbuffer, input, output);
+}
+
 /*** End of code common to polarSSL version 1.2 and 1.3 ***/
 
 /* check polarssl version */
diff --git a/src/cryptoUtils.c b/src/cryptoUtils.c
index 3ae04e8..6958b7b 100644
--- a/src/cryptoUtils.c
+++ b/src/cryptoUtils.c
@@ -382,6 +382,11 @@ int updateCryptoFunctionPointers(bzrtpChannelContext_t *zrtpChannelContext) {
 			zrtpChannelContext->cipherDecryptionFunction = bzrtpCrypto_aes128CfbDecrypt;
 			zrtpChannelContext->cipherKeyLength = 16;
 			break;
+		case ZRTP_CIPHER_AES3 :
+			zrtpChannelContext->cipherEncryptionFunction = bzrtpCrypto_aes256CfbEncrypt;
+			zrtpChannelContext->cipherDecryptionFunction = bzrtpCrypto_aes256CfbDecrypt;
+			zrtpChannelContext->cipherKeyLength = 32;
+			break;
 		case ZRTP_UNSET_ALGO :
 			zrtpChannelContext->cipherEncryptionFunction = NULL;
 			zrtpChannelContext->cipherDecryptionFunction = NULL;
-- 
2.1.4