rc2.c
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1 /**
2  * @file rc2.c
3  * @brief RC2 block cipher
4  *
5  * @section License
6  *
7  * Copyright (C) 2010-2018 Oryx Embedded SARL. All rights reserved.
8  *
9  * This file is part of CycloneCrypto Open.
10  *
11  * This program is free software; you can redistribute it and/or
12  * modify it under the terms of the GNU General Public License
13  * as published by the Free Software Foundation; either version 2
14  * of the License, or (at your option) any later version.
15  *
16  * This program is distributed in the hope that it will be useful,
17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19  * GNU General Public License for more details.
20  *
21  * You should have received a copy of the GNU General Public License
22  * along with this program; if not, write to the Free Software Foundation,
23  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
24  *
25  * @section Description
26  *
27  * RC2 is a block encryption algorithm, which may be considered as a proposal
28  * for a DES replacement. The input and output block sizes are 64 bits each.
29  * The key size is variable, from one byte up to 128 bytes. Refer to RFC 2268
30  * for more details
31  *
32  * @author Oryx Embedded SARL (www.oryx-embedded.com)
33  * @version 1.9.0
34  **/
35 
36 //Switch to the appropriate trace level
37 #define TRACE_LEVEL CRYPTO_TRACE_LEVEL
38 
39 //Dependencies
40 #include "core/crypto.h"
41 #include "cipher/rc2.h"
42 #include "debug.h"
43 
44 //Check crypto library configuration
45 #if (RC2_SUPPORT == ENABLED)
46 
47 //PITABLE array
48 static uint8_t piTable[256] =
49 {
50  0xD9, 0x78, 0xF9, 0xC4, 0x19, 0xDD, 0xB5, 0xED, 0x28, 0xE9, 0xFD, 0x79, 0x4A, 0xA0, 0xD8, 0x9D,
51  0xC6, 0x7E, 0x37, 0x83, 0x2B, 0x76, 0x53, 0x8E, 0x62, 0x4C, 0x64, 0x88, 0x44, 0x8B, 0xFB, 0xA2,
52  0x17, 0x9A, 0x59, 0xF5, 0x87, 0xB3, 0x4F, 0x13, 0x61, 0x45, 0x6D, 0x8D, 0x09, 0x81, 0x7D, 0x32,
53  0xBD, 0x8F, 0x40, 0xEB, 0x86, 0xB7, 0x7B, 0x0B, 0xF0, 0x95, 0x21, 0x22, 0x5C, 0x6B, 0x4E, 0x82,
54  0x54, 0xD6, 0x65, 0x93, 0xCE, 0x60, 0xB2, 0x1C, 0x73, 0x56, 0xC0, 0x14, 0xA7, 0x8C, 0xF1, 0xDC,
55  0x12, 0x75, 0xCA, 0x1F, 0x3B, 0xBE, 0xE4, 0xD1, 0x42, 0x3D, 0xD4, 0x30, 0xA3, 0x3C, 0xB6, 0x26,
56  0x6F, 0xBF, 0x0E, 0xDA, 0x46, 0x69, 0x07, 0x57, 0x27, 0xF2, 0x1D, 0x9B, 0xBC, 0x94, 0x43, 0x03,
57  0xF8, 0x11, 0xC7, 0xF6, 0x90, 0xEF, 0x3E, 0xE7, 0x06, 0xC3, 0xD5, 0x2F, 0xC8, 0x66, 0x1E, 0xD7,
58  0x08, 0xE8, 0xEA, 0xDE, 0x80, 0x52, 0xEE, 0xF7, 0x84, 0xAA, 0x72, 0xAC, 0x35, 0x4D, 0x6A, 0x2A,
59  0x96, 0x1A, 0xD2, 0x71, 0x5A, 0x15, 0x49, 0x74, 0x4B, 0x9F, 0xD0, 0x5E, 0x04, 0x18, 0xA4, 0xEC,
60  0xC2, 0xE0, 0x41, 0x6E, 0x0F, 0x51, 0xCB, 0xCC, 0x24, 0x91, 0xAF, 0x50, 0xA1, 0xF4, 0x70, 0x39,
61  0x99, 0x7C, 0x3A, 0x85, 0x23, 0xB8, 0xB4, 0x7A, 0xFC, 0x02, 0x36, 0x5B, 0x25, 0x55, 0x97, 0x31,
62  0x2D, 0x5D, 0xFA, 0x98, 0xE3, 0x8A, 0x92, 0xAE, 0x05, 0xDF, 0x29, 0x10, 0x67, 0x6C, 0xBA, 0xC9,
63  0xD3, 0x00, 0xE6, 0xCF, 0xE1, 0x9E, 0xA8, 0x2C, 0x63, 0x16, 0x01, 0x3F, 0x58, 0xE2, 0x89, 0xA9,
64  0x0D, 0x38, 0x34, 0x1B, 0xAB, 0x33, 0xFF, 0xB0, 0xBB, 0x48, 0x0C, 0x5F, 0xB9, 0xB1, 0xCD, 0x2E,
65  0xC5, 0xF3, 0xDB, 0x47, 0xE5, 0xA5, 0x9C, 0x77, 0x0A, 0xA6, 0x20, 0x68, 0xFE, 0x7F, 0xC1, 0xAD
66 };
67 
68 //Common interface for encryption algorithms
70 {
71  "RC2",
72  sizeof(Rc2Context),
76  NULL,
77  NULL,
80 };
81 
82 
83 /**
84  * @brief Initialize a RC2 context using the supplied key
85  * @param[in] context Pointer to the RC2 context to initialize
86  * @param[in] key Pointer to the key
87  * @param[in] keyLen Length of the key
88  * @return Error code
89  **/
90 
91 error_t rc2Init(Rc2Context *context, const uint8_t *key, size_t keyLen)
92 {
93  //Initialize a RC2 context
94  return rc2InitEx(context, key, keyLen, keyLen * 8);
95 }
96 
97 
98 /**
99  * @brief Initialize a RC2 context using the supplied key
100  * @param[in] context Pointer to the RC2 context to initialize
101  * @param[in] key Pointer to the key
102  * @param[in] keyLen Length of the key (T)
103  * @param[in] effectiveKeyLen Maximum effective key length, in bits (T1)
104  * @return Error code
105  **/
106 
107 error_t rc2InitEx(Rc2Context *context, const uint8_t *key, size_t keyLen,
108  uint_t effectiveKeyLen)
109 {
110  uint_t i;
111  uint_t t8;
112  uint8_t tm;
113 
114  //Make sure the key length is acceptable
115  if(keyLen < 1 || keyLen > 128)
117 
118  //Make sure the maximum effective key length is acceptable
119  if(effectiveKeyLen < 1 || effectiveKeyLen > 1024)
121 
122  //The key expansion algorithm begins by placing the supplied T-byte key
123  //into bytes L[0], ..., L[T-1] of the key buffer
124  cryptoMemcpy(context->l, key, keyLen);
125 
126  //The key expansion algorithm then computes the effective key length in
127  //bytes T8
128  t8 = (effectiveKeyLen + 7) / 8;
129 
130  //The mask TM has its 8 - (8*T8 - T1) least significant bits set
131  tm = 0xFF >> (8 * t8 - effectiveKeyLen);
132 
133  //First loop of the key expansion operation
134  for(i = keyLen; i < 128; i++)
135  {
136  context->l[i] = piTable[(context->l[i - 1] + context->l[i - keyLen]) & 0xFF];
137  }
138 
139  //The intermediate step's bitwise AND operation reduces the search space
140  //for L[128-T8] so that the effective number of key bits is T1
141  context->l[128 - t8] = piTable[context->l[128 - t8] & tm];
142 
143  //Second loop of the key expansion operation
144  for(i = 128 - t8; i > 0; i--)
145  {
146  context->l[i - 1] = piTable[context->l[i] ^ context->l[i + t8 - 1]];
147  }
148 
149  //The low-order byte of each K word is given before the high-order byte
150  for(i = 0; i < 64; i++)
151  {
152  context->k[i] = letoh16(context->k[i]);
153  }
154 
155  //No error to report
156  return NO_ERROR;
157 }
158 
159 
160 /**
161  * @brief Encrypt a 16-byte block using RC2 algorithm
162  * @param[in] context Pointer to the RC2 context
163  * @param[in] input Plaintext block to encrypt
164  * @param[out] output Ciphertext block resulting from encryption
165  **/
166 
167 void rc2EncryptBlock(Rc2Context *context, const uint8_t *input, uint8_t *output)
168 {
169  int_t i;
170  uint16_t r0;
171  uint16_t r1;
172  uint16_t r2;
173  uint16_t r3;
174 
175  //The plaintext is divided into four 16-bit registers
176  r0 = LOAD16LE(input + 0);
177  r1 = LOAD16LE(input + 2);
178  r2 = LOAD16LE(input + 4);
179  r3 = LOAD16LE(input + 6);
180 
181  //Apply 16 rounds
182  for(i = 0; i < 16; i++)
183  {
184  //Perform mixing round
185  r0 += (r1 & ~r3) + (r2 & r3) + context->k[i * 4];
186  r0 = ROL16(r0, 1);
187  r1 += (r2 & ~r0) + (r3 & r0) + context->k[i * 4 + 1];
188  r1 = ROL16(r1, 2);
189  r2 += (r3 & ~r1) + (r0 & r1) + context->k[i * 4 + 2];
190  r2 = ROL16(r2, 3);
191  r3 += (r0 & ~r2) + (r1 & r2) + context->k[i * 4 + 3];
192  r3 = ROL16(r3, 5);
193 
194  //5th and 11th rounds require special processing
195  if(i == 4 || i == 10)
196  {
197  //Perform mashing round
198  r0 += context->k[r3 % 64];
199  r1 += context->k[r0 % 64];
200  r2 += context->k[r1 % 64];
201  r3 += context->k[r2 % 64];
202  }
203  }
204 
205  //The resulting value is the ciphertext
206  STORE16LE(r0, output + 0);
207  STORE16LE(r1, output + 2);
208  STORE16LE(r2, output + 4);
209  STORE16LE(r3, output + 6);
210 }
211 
212 
213 /**
214  * @brief Decrypt a 16-byte block using RC2 algorithm
215  * @param[in] context Pointer to the RC2 context
216  * @param[in] input Ciphertext block to decrypt
217  * @param[out] output Plaintext block resulting from decryption
218  **/
219 
220 void rc2DecryptBlock(Rc2Context *context, const uint8_t *input, uint8_t *output)
221 {
222  int_t i;
223  uint16_t r0;
224  uint16_t r1;
225  uint16_t r2;
226  uint16_t r3;
227 
228  //The ciphertext is divided into four 16-bit registers
229  r0 = LOAD16LE(input + 0);
230  r1 = LOAD16LE(input + 2);
231  r2 = LOAD16LE(input + 4);
232  r3 = LOAD16LE(input + 6);
233 
234  //Apply 16 rounds
235  for(i = 15; i >= 0; i--)
236  {
237  //Perform r-mixing round
238  r3 = ROR16(r3, 5);
239  r3 -= (r0 & ~r2) + (r1 & r2) + context->k[i * 4 + 3];
240  r2 = ROR16(r2, 3);
241  r2 -= (r3 & ~r1) + (r0 & r1) + context->k[i * 4 + 2];
242  r1 = ROR16(r1, 2);
243  r1 -= (r2 & ~r0) + (r3 & r0) + context->k[i * 4 + 1];
244  r0 = ROR16(r0, 1);
245  r0 -= (r1 & ~r3) + (r2 & r3) + context->k[i * 4];
246 
247  //5th and 11th rounds require special processing
248  if(i == 5 || i == 11)
249  {
250  //Perform r-mashing round
251  r3 -= context->k[r2 % 64];
252  r2 -= context->k[r1 % 64];
253  r1 -= context->k[r0 % 64];
254  r0 -= context->k[r3 % 64];
255  }
256  }
257 
258  //The resulting value is the plaintext
259  STORE16LE(r0, output + 0);
260  STORE16LE(r1, output + 2);
261  STORE16LE(r2, output + 4);
262  STORE16LE(r3, output + 6);
263 }
264 
265 #endif
void rc2EncryptBlock(Rc2Context *context, const uint8_t *input, uint8_t *output)
Encrypt a 16-byte block using RC2 algorithm.
Definition: rc2.c:167
const CipherAlgo rc2CipherAlgo
Definition: rc2.c:69
#define cryptoMemcpy(dest, src, length)
Definition: crypto.h:590
RC2 algorithm context.
Definition: rc2.h:50
Debugging facilities.
void(* CipherAlgoDecryptBlock)(void *context, const uint8_t *input, uint8_t *output)
Definition: crypto.h:1030
#define letoh16(value)
Definition: cpu_endian.h:411
General definitions for cryptographic algorithms.
RC2 block cipher.
Common interface for encryption algorithms.
Definition: crypto.h:1073
#define LOAD16LE(p)
Definition: cpu_endian.h:163
void rc2DecryptBlock(Rc2Context *context, const uint8_t *input, uint8_t *output)
Decrypt a 16-byte block using RC2 algorithm.
Definition: rc2.c:220
uint16_t k[64]
Definition: rc2.h:54
#define STORE16LE(a, p)
Definition: cpu_endian.h:239
uint8_t l[128]
Definition: rc2.h:55
error_t rc2Init(Rc2Context *context, const uint8_t *key, size_t keyLen)
Initialize a RC2 context using the supplied key.
Definition: rc2.c:91
error_t(* CipherAlgoInit)(void *context, const uint8_t *key, size_t keyLen)
Definition: crypto.h:1026
#define ROL16(a, n)
Definition: crypto.h:848
signed int int_t
Definition: compiler_port.h:42
error_t rc2InitEx(Rc2Context *context, const uint8_t *key, size_t keyLen, uint_t effectiveKeyLen)
Initialize a RC2 context using the supplied key.
Definition: rc2.c:107
#define RC2_BLOCK_SIZE
Definition: rc2.h:36
#define ROR16(a, n)
Definition: crypto.h:854
Success.
Definition: error.h:42
error_t
Error codes.
Definition: error.h:40
unsigned int uint_t
Definition: compiler_port.h:43
void(* CipherAlgoEncryptBlock)(void *context, const uint8_t *input, uint8_t *output)
Definition: crypto.h:1029