des3.c

00001 /**
00002  * @file des3.c
00003  * @brief Triple DES (Triple Data Encryption Algorithm)
00004  *
00005  * @section License
00006  *
00007  * Copyright (C) 2010-2017 Oryx Embedded SARL. All rights reserved.
00008  *
00009  * This file is part of CycloneCrypto Open.
00010  *
00011  * This program is free software; you can redistribute it and/or
00012  * modify it under the terms of the GNU General Public License
00013  * as published by the Free Software Foundation; either version 2
00014  * of the License, or (at your option) any later version.
00015  *
00016  * This program is distributed in the hope that it will be useful,
00017  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00018  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00019  * GNU General Public License for more details.
00020  *
00021  * You should have received a copy of the GNU General Public License
00022  * along with this program; if not, write to the Free Software Foundation,
00023  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
00024  *
00025  * @section Description
00026  *
00027  * Triple DES is an encryption algorithm designed to encipher and decipher blocks
00028  * of 64 bits under control of a 192-bit key. Refer to FIPS 46-3 for more details
00029  *
00030  * @author Oryx Embedded SARL (www.oryx-embedded.com)
00031  * @version 1.7.6
00032  **/
00033 
00034 //Switch to the appropriate trace level
00035 #define TRACE_LEVEL CRYPTO_TRACE_LEVEL
00036 
00037 //Dependencies
00038 #include <string.h>
00039 #include "crypto.h"
00040 #include "des3.h"
00041 #include "des.h"
00042 
00043 //Check crypto library configuration
00044 #if (DES3_SUPPORT == ENABLED)
00045 
00046 //Common interface for encryption algorithms
00047 const CipherAlgo des3CipherAlgo =
00048 {
00049    "3DES",
00050    sizeof(Des3Context),
00051    CIPHER_ALGO_TYPE_BLOCK,
00052    DES3_BLOCK_SIZE,
00053    (CipherAlgoInit) des3Init,
00054    NULL,
00055    NULL,
00056    (CipherAlgoEncryptBlock) des3EncryptBlock,
00057    (CipherAlgoDecryptBlock) des3DecryptBlock
00058 };
00059 
00060 
00061 /**
00062  * @brief Initialize a Triple DES context using the supplied key
00063  * @param[in] context Pointer to the Triple DES context to initialize
00064  * @param[in] key Pointer to the key
00065  * @param[in] keyLength Length of the key
00066  * @return Error code
00067  **/
00068 
00069 error_t des3Init(Des3Context *context, const uint8_t *key, size_t keyLength)
00070 {
00071    //Check key length
00072    if(keyLength == 8)
00073    {
00074       //This option provides backward compatibility with DES, because the
00075       //first and second DES operations cancel out
00076       desInit(&context->k1, key, 8);
00077       desInit(&context->k2, key, 8);
00078       desInit(&context->k3, key, 8);
00079    }
00080    else if(keyLength == 16)
00081    {
00082       //If the key length is 128 bits including parity, the first 8 bytes of the
00083       //encoding represent the key used for the two outer DES operations, and
00084       //the second 8 bytes represent the key used for the inner DES operation
00085       desInit(&context->k1, key, 8);
00086       desInit(&context->k2, key + 8, 8);
00087       desInit(&context->k3, key, 8);
00088    }
00089    else if(keyLength == 24)
00090    {
00091       //If the key length is 192 bits including parity, then three independent DES
00092       //keys are represented, in the order in which they are used for encryption
00093       desInit(&context->k1, key, 8);
00094       desInit(&context->k2, key + 8, 8);
00095       desInit(&context->k3, key + 16, 8);
00096    }
00097    else
00098    {
00099       //Invalid key length...
00100       return ERROR_INVALID_KEY_LENGTH;
00101    }
00102 
00103    //No error to report
00104    return NO_ERROR;
00105 }
00106 
00107 
00108 /**
00109  * @brief Encrypt a 8-byte block using Triple DES algorithm
00110  * @param[in] context Pointer to the Triple DES context
00111  * @param[in] input Plaintext block to encrypt
00112  * @param[out] output Ciphertext block resulting from encryption
00113  **/
00114 
00115 void des3EncryptBlock(Des3Context *context, const uint8_t *input, uint8_t *output)
00116 {
00117    //The first pass is a DES encryption
00118    desEncryptBlock(&context->k1, input, output);
00119    //The second pass is a DES decryption of the first ciphertext result
00120    desDecryptBlock(&context->k2, output, output);
00121    //The third pass is a DES encryption of the second pass result
00122    desEncryptBlock(&context->k3, output, output);
00123 }
00124 
00125 
00126 /**
00127  * @brief Decrypt a 8-byte block using Triple DES algorithm
00128  * @param[in] context Pointer to the Triple DES context
00129  * @param[in] input Ciphertext block to decrypt
00130  * @param[out] output Plaintext block resulting from decryption
00131  **/
00132 
00133 void des3DecryptBlock(Des3Context *context, const uint8_t *input, uint8_t *output)
00134 {
00135    //The first pass is a DES decryption
00136    desDecryptBlock(&context->k3, input, output);
00137    //The second pass is a DES encryption of the first pass result
00138    desEncryptBlock(&context->k2, output, output);
00139    //The third pass is a DES decryption of the second ciphertext result
00140    desDecryptBlock(&context->k1, output, output);
00141 }
00142 
00143 #endif
00144