| /* |
| Copyright (C) 2005, 2004 Erik Eliasson, Johan Bilien |
| |
| This library is free software; you can redistribute it and/or |
| modify it under the terms of the GNU Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 of the License, or (at your option) any later version. |
| |
| This library 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 |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with this library; if not, write to the Free Software |
| Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| |
| * In addition, as a special exception, the copyright holders give |
| * permission to link the code of portions of this program with the |
| * OpenSSL library under certain conditions as described in each |
| * individual source file, and distribute linked combinations |
| * including the two. |
| * You must obey the GNU General Public License in all respects |
| * for all of the code used other than OpenSSL. If you modify |
| * file(s) with this exception, you may extend this exception to your |
| * version of the file(s), but you are not obligated to do so. If you |
| * do not wish to do so, delete this exception statement from your |
| * version. If you delete this exception statement from all source |
| * files in the program, then also delete it here. |
| */ |
| |
| /** |
| * @author Erik Eliasson <eliasson@it.kth.se> |
| * @author Johan Bilien <jobi@via.ecp.fr> |
| * @author Werner Dittmann <Werner.Dittmann@t-online.de> |
| */ |
| |
| extern void initializeGcrypt(); |
| |
| #include <gcrypt.h> // the include of gcrypt |
| #include <stdlib.h> |
| #include <ccrtp/crypto/AesSrtp.h> |
| |
| #include <stdio.h> |
| |
| AesSrtp::AesSrtp(int algo) : key(NULL), algorithm(algo) { |
| initializeGcrypt(); |
| } |
| |
| AesSrtp::AesSrtp( uint8* k, int32 keyLength, int algo) : |
| key(NULL), algorithm(algo) { |
| |
| initializeGcrypt(); |
| setNewKey(k, keyLength); |
| } |
| |
| AesSrtp::~AesSrtp() { |
| if (key) { |
| gcry_cipher_close(static_cast<gcry_cipher_hd_t>(key)); |
| key = NULL; |
| } |
| } |
| |
| bool AesSrtp::setNewKey(const uint8* k, int32 keyLength) { |
| |
| // release an existing key before setting a new one |
| if (key != NULL) { |
| gcry_cipher_close(static_cast<gcry_cipher_hd_t>(key)); |
| key = NULL; |
| } |
| |
| int algo = 0; |
| if (keyLength == 16) { |
| algo = GCRY_CIPHER_AES; |
| } |
| else if (keyLength == 32) { |
| algo = GCRY_CIPHER_AES256; |
| } |
| else { |
| return false; |
| } |
| gcry_cipher_hd_t tmp; |
| int err = gcry_cipher_open(&tmp, algo, GCRY_CIPHER_MODE_ECB, 0); |
| key = tmp; |
| err = gcry_cipher_setkey(static_cast<gcry_cipher_hd_t>(key), k, keyLength); |
| return true; |
| } |
| |
| |
| void AesSrtp::encrypt( const uint8* input, uint8* output ) { |
| if (key != NULL) { |
| gcry_cipher_encrypt (static_cast<gcry_cipher_hd_t>(key), |
| output, SRTP_BLOCK_SIZE, input, SRTP_BLOCK_SIZE); |
| } |
| } |
| |
| void AesSrtp::get_ctr_cipher_stream( uint8* output, uint32 length, |
| uint8* iv ) { |
| uint16 ctr; |
| uint16 input; |
| |
| unsigned char aes_input[SRTP_BLOCK_SIZE]; |
| unsigned char temp[SRTP_BLOCK_SIZE]; |
| |
| memcpy(aes_input, iv, 14 ); |
| iv += 14; |
| |
| for( ctr = 0; ctr < length/SRTP_BLOCK_SIZE; ctr++ ){ |
| input = ctr; |
| //compute the cipher stream |
| aes_input[14] = (uint8)((input & 0xFF00) >> 8); |
| aes_input[15] = (uint8)((input & 0x00FF)); |
| |
| gcry_cipher_encrypt(static_cast<gcry_cipher_hd_t>(key), &output[ctr*SRTP_BLOCK_SIZE], SRTP_BLOCK_SIZE, |
| aes_input, SRTP_BLOCK_SIZE); |
| } |
| if ((length % SRTP_BLOCK_SIZE) > 0) { |
| // Treat the last bytes: |
| input = ctr; |
| aes_input[14] = (uint8)((input & 0xFF00) >> 8); |
| aes_input[15] = (uint8)((input & 0x00FF)); |
| |
| gcry_cipher_encrypt(static_cast<gcry_cipher_hd_t>(key), temp, SRTP_BLOCK_SIZE, aes_input, SRTP_BLOCK_SIZE); |
| memcpy(&output[ctr*SRTP_BLOCK_SIZE], temp, length % SRTP_BLOCK_SIZE); |
| } |
| } |
| |
| |
| void AesSrtp::ctr_encrypt( const uint8* input, uint32 input_length, |
| uint8* output, uint8* iv ) { |
| |
| if (key == NULL) |
| return; |
| |
| uint8* cipher_stream = new uint8[input_length]; |
| |
| get_ctr_cipher_stream( cipher_stream, input_length, iv ); |
| |
| for( unsigned int i = 0; i < input_length; i++ ){ |
| output[i] = cipher_stream[i] ^ input[i]; |
| } |
| delete []cipher_stream; |
| } |
| |
| void AesSrtp::ctr_encrypt( uint8* data, uint32 data_length, uint8* iv ) { |
| |
| if (key == NULL) |
| return; |
| |
| //unsigned char cipher_stream[data_length]; |
| uint8* cipher_stream = new uint8[data_length]; |
| |
| get_ctr_cipher_stream( cipher_stream, data_length, iv ); |
| |
| for( uint32 i = 0; i < data_length; i++ ){ |
| data[i] ^= cipher_stream[i]; |
| } |
| delete[] cipher_stream; |
| } |
| |
| void AesSrtp::f8_encrypt(const uint8* data, uint32 data_length, |
| uint8* iv, uint8* origKey, int32 keyLen, |
| uint8* salt, int32 saltLen, AesSrtp* f8Cipher ) { |
| |
| f8_encrypt(data, data_length, const_cast<uint8*>(data), iv, origKey, keyLen, salt, saltLen, f8Cipher); |
| } |
| |
| #define MAX_KEYLEN 32 |
| |
| void AesSrtp::f8_encrypt(const uint8* in, uint32 in_length, uint8* out, |
| uint8* iv, uint8* origKey, int32 keyLen, |
| uint8* salt, int32 saltLen, AesSrtp* f8Cipher ) { |
| |
| |
| unsigned char *cp_in, *cp_in1, *cp_out; |
| int i; |
| int offset = 0; |
| |
| unsigned char ivAccent[SRTP_BLOCK_SIZE]; |
| unsigned char maskedKey[MAX_KEYLEN]; |
| unsigned char saltMask[MAX_KEYLEN]; |
| unsigned char S[SRTP_BLOCK_SIZE]; |
| |
| F8_CIPHER_CTX f8ctx; |
| |
| if (key == NULL) |
| return; |
| |
| if (keyLen > MAX_KEYLEN) |
| return; |
| |
| if (saltLen > keyLen) |
| return; |
| |
| /* |
| * Get memory for the derived IV (IV') |
| */ |
| f8ctx.ivAccent = ivAccent; |
| |
| /* |
| * First copy the salt into the mask field, then fill with 0x55 to |
| * get a full key. |
| */ |
| memcpy(saltMask, salt, saltLen); |
| memset(saltMask+saltLen, 0x55, keyLen-saltLen); |
| |
| /* |
| * XOR the original key with the above created mask to |
| * get the special key. |
| */ |
| cp_out = maskedKey; |
| cp_in = origKey; |
| cp_in1 = saltMask; |
| for (i = 0; i < keyLen; i++) { |
| *cp_out++ = *cp_in++ ^ *cp_in1++; |
| } |
| /* |
| * Prepare the a new AES cipher with the special key to compute IV' |
| */ |
| f8Cipher->setNewKey(maskedKey, keyLen); |
| |
| /* |
| * Use the masked key to encrypt the original IV to produce IV'. |
| * |
| * After computing the IV' we don't need this cipher context anymore, free it. |
| */ |
| f8Cipher->encrypt(iv, f8ctx.ivAccent); |
| |
| f8ctx.J = 0; // initialize the counter |
| f8ctx.S = S; // get the key stream buffer |
| |
| memset(f8ctx.S, 0, SRTP_BLOCK_SIZE); // initial value for key stream |
| |
| while (in_length >= SRTP_BLOCK_SIZE) { |
| processBlock(&f8ctx, in+offset, SRTP_BLOCK_SIZE, out+offset); |
| in_length -= SRTP_BLOCK_SIZE; |
| offset += SRTP_BLOCK_SIZE; |
| } |
| if (in_length > 0) { |
| processBlock(&f8ctx, in+offset, in_length, out+offset); |
| } |
| } |
| |
| int AesSrtp::processBlock(F8_CIPHER_CTX *f8ctx, const uint8* in, int32 length, uint8* out) { |
| |
| int i; |
| const uint8 *cp_in; |
| uint8* cp_in1, *cp_out; |
| uint32_t *ui32p; |
| |
| /* |
| * XOR the previous key stream with IV' |
| * ( S(-1) xor IV' ) |
| */ |
| cp_in = f8ctx->ivAccent; |
| cp_out = f8ctx->S; |
| for (i = 0; i < SRTP_BLOCK_SIZE; i++) { |
| *cp_out++ ^= *cp_in++; |
| } |
| /* |
| * Now XOR (S(n-1) xor IV') with the current counter, then increment the counter |
| */ |
| ui32p = (uint32_t *)f8ctx->S; |
| ui32p[3] ^= htonl(f8ctx->J); |
| f8ctx->J++; |
| /* |
| * Now compute the new key stream using AES encrypt |
| */ |
| gcry_cipher_encrypt(static_cast<gcry_cipher_hd_t>(key), f8ctx->S, SRTP_BLOCK_SIZE, NULL, 0); |
| /* |
| * as the last step XOR the plain text with the key stream to produce |
| * the ciphertext. |
| */ |
| cp_out = out; |
| cp_in = in; |
| cp_in1 = f8ctx->S; |
| for (i = 0; i < length; i++) { |
| *cp_out++ = *cp_in++ ^ *cp_in1++; |
| } |
| return length; |
| } |
| |
| |
| /** EMACS ** |
| * Local variables: |
| * mode: c++ |
| * c-default-style: ellemtel |
| * c-basic-offset: 4 |
| * End: |
| */ |
| |
| |