Crypto++  5.6.3
Free C++ class library of cryptographic schemes
rc2.cpp
1 // rc2.cpp - written and placed in the public domain by Wei Dai
2 
3 #include "pch.h"
4 #include "rc2.h"
5 #include "misc.h"
6 #include "argnames.h"
7 
8 NAMESPACE_BEGIN(CryptoPP)
9 
10 void RC2::Base::UncheckedSetKey(const byte *key, unsigned int keyLen, const NameValuePairs &params)
11 {
12  AssertValidKeyLength(keyLen);
13 
14  int effectiveLen = params.GetIntValueWithDefault(Name::EffectiveKeyLength(), DEFAULT_EFFECTIVE_KEYLENGTH);
15  if (effectiveLen > MAX_EFFECTIVE_KEYLENGTH)
16  throw InvalidArgument("RC2: effective key length parameter exceeds maximum");
17 
18  static const unsigned char PITABLE[256] = {
19  217,120,249,196, 25,221,181,237, 40,233,253,121, 74,160,216,157,
20  198,126, 55,131, 43,118, 83,142, 98, 76,100,136, 68,139,251,162,
21  23,154, 89,245,135,179, 79, 19, 97, 69,109,141, 9,129,125, 50,
22  189,143, 64,235,134,183,123, 11,240,149, 33, 34, 92,107, 78,130,
23  84,214,101,147,206, 96,178, 28,115, 86,192, 20,167,140,241,220,
24  18,117,202, 31, 59,190,228,209, 66, 61,212, 48,163, 60,182, 38,
25  111,191, 14,218, 70,105, 7, 87, 39,242, 29,155,188,148, 67, 3,
26  248, 17,199,246,144,239, 62,231, 6,195,213, 47,200,102, 30,215,
27  8,232,234,222,128, 82,238,247,132,170,114,172, 53, 77,106, 42,
28  150, 26,210,113, 90, 21, 73,116, 75,159,208, 94, 4, 24,164,236,
29  194,224, 65,110, 15, 81,203,204, 36,145,175, 80,161,244,112, 57,
30  153,124, 58,133, 35,184,180,122,252, 2, 54, 91, 37, 85,151, 49,
31  45, 93,250,152,227,138,146,174, 5,223, 41, 16,103,108,186,201,
32  211, 0,230,207,225,158,168, 44, 99, 22, 1, 63, 88,226,137,169,
33  13, 56, 52, 27,171, 51,255,176,187, 72, 12, 95,185,177,205, 46,
34  197,243,219, 71,229,165,156,119, 10,166, 32,104,254,127,193,173};
35 
36  SecByteBlock L(128);
37  memcpy(L, key, keyLen);
38 
39  int i;
40  for (i=keyLen; i<128; i++)
41  L[i] = PITABLE[(L[i-1] + L[i-keyLen]) & 255];
42 
43  unsigned int T8 = (effectiveLen+7) / 8;
44  byte TM = byte((int)255 >> ((8-(effectiveLen%8))%8));
45  L[128-T8] = PITABLE[L[128-T8] & TM];
46 
47  for (i=127-T8; i>=0; i--)
48  L[i] = PITABLE[L[i+1] ^ L[i+T8]];
49 
50  for (i=0; i<64; i++)
51  K[i] = L[2*i] + (L[2*i+1] << 8);
52 }
53 
55 
56 void RC2::Enc::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
57 {
58  word16 R0, R1, R2, R3;
59  Block::Get(inBlock)(R0)(R1)(R2)(R3);
60 
61  for (int i = 0; i < 16; i++)
62  {
63  R0 += (R1 & ~R3) + (R2 & R3) + K[4*i+0];
64  R0 = rotlFixed(R0, 1);
65 
66  R1 += (R2 & ~R0) + (R3 & R0) + K[4*i+1];
67  R1 = rotlFixed(R1, 2);
68 
69  R2 += (R3 & ~R1) + (R0 & R1) + K[4*i+2];
70  R2 = rotlFixed(R2, 3);
71 
72  R3 += (R0 & ~R2) + (R1 & R2) + K[4*i+3];
73  R3 = rotlFixed(R3, 5);
74 
75  if (i == 4 || i == 10)
76  {
77  R0 = word16(R0 + K[R3 & 63]);
78  R1 = word16(R1 + K[R0 & 63]);
79  R2 = word16(R2 + K[R1 & 63]);
80  R3 = word16(R3 + K[R2 & 63]);
81  }
82  }
83 
84  Block::Put(xorBlock, outBlock)(R0)(R1)(R2)(R3);
85 }
86 
87 void RC2::Dec::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
88 {
89  word16 R0, R1, R2, R3;
90  Block::Get(inBlock)(R0)(R1)(R2)(R3);
91 
92  for (int i = 15; i >= 0; i--)
93  {
94  if (i == 4 || i == 10)
95  {
96  R3 = word16(R3 - K[R2 & 63]);
97  R2 = word16(R2 - K[R1 & 63]);
98  R1 = word16(R1 - K[R0 & 63]);
99  R0 = word16(R0 - K[R3 & 63]);
100  }
101 
102  R3 = rotrFixed(R3, 5);
103  R3 = word16(R3 - ((R0 & ~R2) + (R1 & R2) + K[4*i+3]));
104 
105  R2 = rotrFixed(R2, 3);
106  R2 = word16(R2 - ((R3 & ~R1) + (R0 & R1) + K[4*i+2]));
107 
108  R1 = rotrFixed(R1, 2);
109  R1 = word16(R1 - ((R2 & ~R0) + (R3 & R0) + K[4*i+1]));
110 
111  R0 = rotrFixed(R0, 1);
112  R0 = word16(R0 - ((R1 & ~R3) + (R2 & R3) + K[4*i+0]));
113  }
114 
115  Block::Put(xorBlock, outBlock)(R0)(R1)(R2)(R3);
116 }
117 
118 NAMESPACE_END
Standard names for retrieving values by name when working with NameValuePairs.
An invalid argument was detected.
Definition: cryptlib.h:182
Utility functions for the Crypto++ library.
T rotlFixed(T x, unsigned int y)
Performs a left rotate.
Definition: misc.h:1304
Classes for the RC2 block cipher.
Access a block of memory.
Definition: misc.h:2228
SecBlock typedef.
Definition: secblock.h:728
RC2 block cipher.
Definition: rc2.h:27
Access a block of memory.
Definition: misc.h:2190
Crypto++ library namespace.
T rotrFixed(T x, unsigned int y)
Performs a right rotate.
Definition: misc.h:1325
const char * EffectiveKeyLength()
int, in bits
Definition: argnames.h:27
Interface for retrieving values given their names.
Definition: cryptlib.h:277