rc2.c
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1 /**
2  * @file rc2.c
3  * @brief RC2 block cipher
4  *
5  * @section License
6  *
7  * SPDX-License-Identifier: GPL-2.0-or-later
8  *
9  * Copyright (C) 2010-2019 Oryx Embedded SARL. All rights reserved.
10  *
11  * This file is part of CycloneCrypto Open.
12  *
13  * This program is free software; you can redistribute it and/or
14  * modify it under the terms of the GNU General Public License
15  * as published by the Free Software Foundation; either version 2
16  * of the License, or (at your option) any later version.
17  *
18  * This program is distributed in the hope that it will be useful,
19  * but WITHOUT ANY WARRANTY; without even the implied warranty of
20  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
21  * GNU General Public License for more details.
22  *
23  * You should have received a copy of the GNU General Public License
24  * along with this program; if not, write to the Free Software Foundation,
25  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
26  *
27  * @section Description
28  *
29  * RC2 is a block encryption algorithm, which may be considered as a proposal
30  * for a DES replacement. The input and output block sizes are 64 bits each.
31  * The key size is variable, from one byte up to 128 bytes. Refer to RFC 2268
32  * for more details
33  *
34  * @author Oryx Embedded SARL (www.oryx-embedded.com)
35  * @version 1.9.6
36  **/
37 
38 //Switch to the appropriate trace level
39 #define TRACE_LEVEL CRYPTO_TRACE_LEVEL
40 
41 //Dependencies
42 #include "core/crypto.h"
43 #include "cipher/rc2.h"
44 #include "debug.h"
45 
46 //Check crypto library configuration
47 #if (RC2_SUPPORT == ENABLED)
48 
49 //PITABLE array
50 static uint8_t piTable[256] =
51 {
52  0xD9, 0x78, 0xF9, 0xC4, 0x19, 0xDD, 0xB5, 0xED, 0x28, 0xE9, 0xFD, 0x79, 0x4A, 0xA0, 0xD8, 0x9D,
53  0xC6, 0x7E, 0x37, 0x83, 0x2B, 0x76, 0x53, 0x8E, 0x62, 0x4C, 0x64, 0x88, 0x44, 0x8B, 0xFB, 0xA2,
54  0x17, 0x9A, 0x59, 0xF5, 0x87, 0xB3, 0x4F, 0x13, 0x61, 0x45, 0x6D, 0x8D, 0x09, 0x81, 0x7D, 0x32,
55  0xBD, 0x8F, 0x40, 0xEB, 0x86, 0xB7, 0x7B, 0x0B, 0xF0, 0x95, 0x21, 0x22, 0x5C, 0x6B, 0x4E, 0x82,
56  0x54, 0xD6, 0x65, 0x93, 0xCE, 0x60, 0xB2, 0x1C, 0x73, 0x56, 0xC0, 0x14, 0xA7, 0x8C, 0xF1, 0xDC,
57  0x12, 0x75, 0xCA, 0x1F, 0x3B, 0xBE, 0xE4, 0xD1, 0x42, 0x3D, 0xD4, 0x30, 0xA3, 0x3C, 0xB6, 0x26,
58  0x6F, 0xBF, 0x0E, 0xDA, 0x46, 0x69, 0x07, 0x57, 0x27, 0xF2, 0x1D, 0x9B, 0xBC, 0x94, 0x43, 0x03,
59  0xF8, 0x11, 0xC7, 0xF6, 0x90, 0xEF, 0x3E, 0xE7, 0x06, 0xC3, 0xD5, 0x2F, 0xC8, 0x66, 0x1E, 0xD7,
60  0x08, 0xE8, 0xEA, 0xDE, 0x80, 0x52, 0xEE, 0xF7, 0x84, 0xAA, 0x72, 0xAC, 0x35, 0x4D, 0x6A, 0x2A,
61  0x96, 0x1A, 0xD2, 0x71, 0x5A, 0x15, 0x49, 0x74, 0x4B, 0x9F, 0xD0, 0x5E, 0x04, 0x18, 0xA4, 0xEC,
62  0xC2, 0xE0, 0x41, 0x6E, 0x0F, 0x51, 0xCB, 0xCC, 0x24, 0x91, 0xAF, 0x50, 0xA1, 0xF4, 0x70, 0x39,
63  0x99, 0x7C, 0x3A, 0x85, 0x23, 0xB8, 0xB4, 0x7A, 0xFC, 0x02, 0x36, 0x5B, 0x25, 0x55, 0x97, 0x31,
64  0x2D, 0x5D, 0xFA, 0x98, 0xE3, 0x8A, 0x92, 0xAE, 0x05, 0xDF, 0x29, 0x10, 0x67, 0x6C, 0xBA, 0xC9,
65  0xD3, 0x00, 0xE6, 0xCF, 0xE1, 0x9E, 0xA8, 0x2C, 0x63, 0x16, 0x01, 0x3F, 0x58, 0xE2, 0x89, 0xA9,
66  0x0D, 0x38, 0x34, 0x1B, 0xAB, 0x33, 0xFF, 0xB0, 0xBB, 0x48, 0x0C, 0x5F, 0xB9, 0xB1, 0xCD, 0x2E,
67  0xC5, 0xF3, 0xDB, 0x47, 0xE5, 0xA5, 0x9C, 0x77, 0x0A, 0xA6, 0x20, 0x68, 0xFE, 0x7F, 0xC1, 0xAD
68 };
69 
70 //Common interface for encryption algorithms
72 {
73  "RC2",
74  sizeof(Rc2Context),
78  NULL,
79  NULL,
82 };
83 
84 
85 /**
86  * @brief Initialize a RC2 context using the supplied key
87  * @param[in] context Pointer to the RC2 context to initialize
88  * @param[in] key Pointer to the key
89  * @param[in] keyLen Length of the key
90  * @return Error code
91  **/
92 
93 error_t rc2Init(Rc2Context *context, const uint8_t *key, size_t keyLen)
94 {
95  //Initialize a RC2 context
96  return rc2InitEx(context, key, keyLen, keyLen * 8);
97 }
98 
99 
100 /**
101  * @brief Initialize a RC2 context using the supplied key
102  * @param[in] context Pointer to the RC2 context to initialize
103  * @param[in] key Pointer to the key
104  * @param[in] keyLen Length of the key (T)
105  * @param[in] effectiveKeyLen Maximum effective key length, in bits (T1)
106  * @return Error code
107  **/
108 
109 error_t rc2InitEx(Rc2Context *context, const uint8_t *key, size_t keyLen,
110  uint_t effectiveKeyLen)
111 {
112  uint_t i;
113  uint_t t8;
114  uint8_t tm;
115 
116  //Check parameters
117  if(context == NULL || key == NULL)
119 
120  //Make sure the key length is acceptable
121  if(keyLen < 1 || keyLen > 128)
123 
124  //Make sure the maximum effective key length is acceptable
125  if(effectiveKeyLen < 1 || effectiveKeyLen > 1024)
127 
128  //The key expansion algorithm begins by placing the supplied T-byte key
129  //into bytes L[0], ..., L[T-1] of the key buffer
130  cryptoMemcpy(context->l, key, keyLen);
131 
132  //The key expansion algorithm then computes the effective key length in
133  //bytes T8
134  t8 = (effectiveKeyLen + 7) / 8;
135 
136  //The mask TM has its 8 - (8*T8 - T1) least significant bits set
137  tm = 0xFF >> (8 * t8 - effectiveKeyLen);
138 
139  //First loop of the key expansion operation
140  for(i = keyLen; i < 128; i++)
141  {
142  context->l[i] = piTable[(context->l[i - 1] + context->l[i - keyLen]) & 0xFF];
143  }
144 
145  //The intermediate step's bitwise AND operation reduces the search space
146  //for L[128-T8] so that the effective number of key bits is T1
147  context->l[128 - t8] = piTable[context->l[128 - t8] & tm];
148 
149  //Second loop of the key expansion operation
150  for(i = 128 - t8; i > 0; i--)
151  {
152  context->l[i - 1] = piTable[context->l[i] ^ context->l[i + t8 - 1]];
153  }
154 
155  //The low-order byte of each K word is given before the high-order byte
156  for(i = 0; i < 64; i++)
157  {
158  context->k[i] = letoh16(context->k[i]);
159  }
160 
161  //No error to report
162  return NO_ERROR;
163 }
164 
165 
166 /**
167  * @brief Encrypt a 16-byte block using RC2 algorithm
168  * @param[in] context Pointer to the RC2 context
169  * @param[in] input Plaintext block to encrypt
170  * @param[out] output Ciphertext block resulting from encryption
171  **/
172 
173 void rc2EncryptBlock(Rc2Context *context, const uint8_t *input, uint8_t *output)
174 {
175  int_t i;
176  uint16_t r0;
177  uint16_t r1;
178  uint16_t r2;
179  uint16_t r3;
180 
181  //The plaintext is divided into four 16-bit registers
182  r0 = LOAD16LE(input + 0);
183  r1 = LOAD16LE(input + 2);
184  r2 = LOAD16LE(input + 4);
185  r3 = LOAD16LE(input + 6);
186 
187  //Apply 16 rounds
188  for(i = 0; i < 16; i++)
189  {
190  //Perform mixing round
191  r0 += (r1 & ~r3) + (r2 & r3) + context->k[i * 4];
192  r0 = ROL16(r0, 1);
193  r1 += (r2 & ~r0) + (r3 & r0) + context->k[i * 4 + 1];
194  r1 = ROL16(r1, 2);
195  r2 += (r3 & ~r1) + (r0 & r1) + context->k[i * 4 + 2];
196  r2 = ROL16(r2, 3);
197  r3 += (r0 & ~r2) + (r1 & r2) + context->k[i * 4 + 3];
198  r3 = ROL16(r3, 5);
199 
200  //5th and 11th rounds require special processing
201  if(i == 4 || i == 10)
202  {
203  //Perform mashing round
204  r0 += context->k[r3 % 64];
205  r1 += context->k[r0 % 64];
206  r2 += context->k[r1 % 64];
207  r3 += context->k[r2 % 64];
208  }
209  }
210 
211  //The resulting value is the ciphertext
212  STORE16LE(r0, output + 0);
213  STORE16LE(r1, output + 2);
214  STORE16LE(r2, output + 4);
215  STORE16LE(r3, output + 6);
216 }
217 
218 
219 /**
220  * @brief Decrypt a 16-byte block using RC2 algorithm
221  * @param[in] context Pointer to the RC2 context
222  * @param[in] input Ciphertext block to decrypt
223  * @param[out] output Plaintext block resulting from decryption
224  **/
225 
226 void rc2DecryptBlock(Rc2Context *context, const uint8_t *input, uint8_t *output)
227 {
228  int_t i;
229  uint16_t r0;
230  uint16_t r1;
231  uint16_t r2;
232  uint16_t r3;
233 
234  //The ciphertext is divided into four 16-bit registers
235  r0 = LOAD16LE(input + 0);
236  r1 = LOAD16LE(input + 2);
237  r2 = LOAD16LE(input + 4);
238  r3 = LOAD16LE(input + 6);
239 
240  //Apply 16 rounds
241  for(i = 15; i >= 0; i--)
242  {
243  //Perform r-mixing round
244  r3 = ROR16(r3, 5);
245  r3 -= (r0 & ~r2) + (r1 & r2) + context->k[i * 4 + 3];
246  r2 = ROR16(r2, 3);
247  r2 -= (r3 & ~r1) + (r0 & r1) + context->k[i * 4 + 2];
248  r1 = ROR16(r1, 2);
249  r1 -= (r2 & ~r0) + (r3 & r0) + context->k[i * 4 + 1];
250  r0 = ROR16(r0, 1);
251  r0 -= (r1 & ~r3) + (r2 & r3) + context->k[i * 4];
252 
253  //5th and 11th rounds require special processing
254  if(i == 5 || i == 11)
255  {
256  //Perform r-mashing round
257  r3 -= context->k[r2 % 64];
258  r2 -= context->k[r1 % 64];
259  r1 -= context->k[r0 % 64];
260  r0 -= context->k[r3 % 64];
261  }
262  }
263 
264  //The resulting value is the plaintext
265  STORE16LE(r0, output + 0);
266  STORE16LE(r1, output + 2);
267  STORE16LE(r2, output + 4);
268  STORE16LE(r3, output + 6);
269 }
270 
271 #endif
error_t rc2Init(Rc2Context *context, const uint8_t *key, size_t keyLen)
Initialize a RC2 context using the supplied key.
Definition: rc2.c:93
signed int int_t
Definition: compiler_port.h:44
void(* CipherAlgoEncryptBlock)(void *context, const uint8_t *input, uint8_t *output)
Definition: crypto.h:1103
@ CIPHER_ALGO_TYPE_BLOCK
Definition: crypto.h:1069
#define STORE16LE(a, p)
Definition: cpu_endian.h:241
void rc2EncryptBlock(Rc2Context *context, const uint8_t *input, uint8_t *output)
Encrypt a 16-byte block using RC2 algorithm.
Definition: rc2.c:173
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:109
#define RC2_BLOCK_SIZE
Definition: rc2.h:38
#define LOAD16LE(p)
Definition: cpu_endian.h:165
RC2 algorithm context.
Definition: rc2.h:52
uint8_t l[128]
Definition: rc2.h:57
@ ERROR_INVALID_PARAMETER
Invalid parameter.
Definition: error.h:47
error_t
Error codes.
Definition: error.h:42
void(* CipherAlgoDecryptBlock)(void *context, const uint8_t *input, uint8_t *output)
Definition: crypto.h:1104
@ ERROR_INVALID_KEY_LENGTH
Definition: error.h:105
void rc2DecryptBlock(Rc2Context *context, const uint8_t *input, uint8_t *output)
Decrypt a 16-byte block using RC2 algorithm.
Definition: rc2.c:226
General definitions for cryptographic algorithms.
error_t(* CipherAlgoInit)(void *context, const uint8_t *key, size_t keyLen)
Definition: crypto.h:1100
#define cryptoMemcpy(dest, src, length)
Definition: crypto.h:642
#define ROL16(a, n)
Definition: crypto.h:916
Common interface for encryption algorithms.
Definition: crypto.h:1150
#define ROR16(a, n)
Definition: crypto.h:922
const CipherAlgo rc2CipherAlgo
Definition: rc2.c:71
#define letoh16(value)
Definition: cpu_endian.h:413
unsigned int uint_t
Definition: compiler_port.h:45
uint16_t k[64]
Definition: rc2.h:56
@ NO_ERROR
Success.
Definition: error.h:44
Debugging facilities.
RC2 block cipher.