← Back to branch summary

~ubuntu-branches/debian/squeeze/pycryptopp/squeeze

« back to all changes in this revision

Viewing changes to cryptopp/modes.cpp

  • Committer: Bazaar Package Importer
  • Author(s): Zooko O'Whielacronx
  • Date: 2009-06-22 22:20:50 UTC
  • Revision ID: james.westby@ubuntu.com-20090622222050-hbqmn50dt2kvoz5o
Tags: upstream-0.5.14
Import upstream version 0.5.14

Show diffs side-by-side

added added

removed removed

Lines of Context:
cryptopp/modes.cpp
 
1
// modes.cpp - written and placed in the public domain by Wei Dai
 
2
 
 
3
#include "pch.h"
 
4
 
 
5
#ifndef CRYPTOPP_IMPORTS
 
6
 
 
7
#include "modes.h"
 
8
 
 
9
#ifndef NDEBUG
 
10
#include "des.h"
 
11
#endif
 
12
 
 
13
NAMESPACE_BEGIN(CryptoPP)
 
14
 
 
15
#ifndef NDEBUG
 
16
void Modes_TestInstantiations()
 
17
{
 
18
        CFB_Mode<DES>::Encryption m0;
 
19
        CFB_Mode<DES>::Decryption m1;
 
20
        OFB_Mode<DES>::Encryption m2;
 
21
        CTR_Mode<DES>::Encryption m3;
 
22
        ECB_Mode<DES>::Encryption m4;
 
23
        CBC_Mode<DES>::Encryption m5;
 
24
}
 
25
#endif
 
26
 
 
27
void CFB_ModePolicy::Iterate(byte *output, const byte *input, CipherDir dir, size_t iterationCount)
 
28
{
 
29
        assert(m_cipher->IsForwardTransformation());    // CFB mode needs the "encrypt" direction of the underlying block cipher, even to decrypt
 
30
        assert(m_feedbackSize == BlockSize());
 
31
 
 
32
        unsigned int s = BlockSize();
 
33
        if (dir == ENCRYPTION)
 
34
        {
 
35
                m_cipher->ProcessAndXorBlock(m_register, input, output);
 
36
                m_cipher->AdvancedProcessBlocks(output, input+s, output+s, (iterationCount-1)*s, 0);
 
37
                memcpy(m_register, output+(iterationCount-1)*s, s);
 
38
        }
 
39
        else
 
40
        {
 
41
                memcpy(m_temp, input+(iterationCount-1)*s, s);  // make copy first in case of in-place decryption
 
42
                m_cipher->AdvancedProcessBlocks(input, input+s, output+s, (iterationCount-1)*s, BlockTransformation::BT_ReverseDirection);
 
43
                m_cipher->ProcessAndXorBlock(m_register, input, output);
 
44
                memcpy(m_register, m_temp, s);
 
45
        }
 
46
}
 
47
 
 
48
void CFB_ModePolicy::TransformRegister()
 
49
{
 
50
        assert(m_cipher->IsForwardTransformation());    // CFB mode needs the "encrypt" direction of the underlying block cipher, even to decrypt
 
51
        m_cipher->ProcessBlock(m_register, m_temp);
 
52
        unsigned int updateSize = BlockSize()-m_feedbackSize;
 
53
        memmove_s(m_register, m_register.size(), m_register+m_feedbackSize, updateSize);
 
54
        memcpy_s(m_register+updateSize, m_register.size()-updateSize, m_temp, m_feedbackSize);
 
55
}
 
56
 
 
57
void CFB_ModePolicy::CipherResynchronize(const byte *iv, size_t length)
 
58
{
 
59
        memcpy_s(m_register, m_register.size(), iv, BlockSize());
 
60
        TransformRegister();
 
61
}
 
62
 
 
63
void CFB_ModePolicy::SetFeedbackSize(unsigned int feedbackSize)
 
64
{
 
65
        if (feedbackSize > BlockSize())
 
66
                throw InvalidArgument("CFB_Mode: invalid feedback size");
 
67
        m_feedbackSize = feedbackSize ? feedbackSize : BlockSize();
 
68
}
 
69
 
 
70
void CFB_ModePolicy::ResizeBuffers()
 
71
{
 
72
        CipherModeBase::ResizeBuffers();
 
73
        m_temp.New(BlockSize());
 
74
}
 
75
 
 
76
void OFB_ModePolicy::WriteKeystream(byte *keystreamBuffer, size_t iterationCount)
 
77
{
 
78
        assert(m_cipher->IsForwardTransformation());    // OFB mode needs the "encrypt" direction of the underlying block cipher, even to decrypt
 
79
        unsigned int s = BlockSize();
 
80
        m_cipher->ProcessBlock(m_register, keystreamBuffer);
 
81
        if (iterationCount > 1)
 
82
                m_cipher->AdvancedProcessBlocks(keystreamBuffer, NULL, keystreamBuffer+s, s*(iterationCount-1), 0);
 
83
        memcpy(m_register, keystreamBuffer+s*(iterationCount-1), s);
 
84
}
 
85
 
 
86
void OFB_ModePolicy::CipherResynchronize(byte *keystreamBuffer, const byte *iv, size_t length)
 
87
{
 
88
        CopyOrZero(m_register, iv, length);
 
89
}
 
90
 
 
91
void CTR_ModePolicy::SeekToIteration(lword iterationCount)
 
92
{
 
93
        int carry=0;
 
94
        for (int i=BlockSize()-1; i>=0; i--)
 
95
        {
 
96
                unsigned int sum = m_register[i] + byte(iterationCount) + carry;
 
97
                m_counterArray[i] = (byte) sum;
 
98
                carry = sum >> 8;
 
99
                iterationCount >>= 8;
 
100
        }
 
101
}
 
102
 
 
103
void CTR_ModePolicy::IncrementCounterBy256()
 
104
{
 
105
        IncrementCounterByOne(m_counterArray, BlockSize()-1);
 
106
}
 
107
 
 
108
void CTR_ModePolicy::OperateKeystream(KeystreamOperation operation, byte *output, const byte *input, size_t iterationCount)
 
109
{
 
110
        assert(m_cipher->IsForwardTransformation());    // CTR mode needs the "encrypt" direction of the underlying block cipher, even to decrypt
 
111
        unsigned int s = BlockSize();
 
112
        unsigned int inputIncrement = input ? s : 0;
 
113
 
 
114
        while (iterationCount)
 
115
        {
 
116
                byte lsb = m_counterArray[s-1];
 
117
                size_t blocks = UnsignedMin(iterationCount, 256U-lsb);
 
118
                m_cipher->AdvancedProcessBlocks(m_counterArray, input, output, blocks*s, BlockTransformation::BT_InBlockIsCounter);
 
119
                if ((m_counterArray[s-1] = lsb + (byte)blocks) == 0)
 
120
                        IncrementCounterBy256();
 
121
 
 
122
                output += blocks*s;
 
123
                input += blocks*inputIncrement;
 
124
                iterationCount -= blocks;
 
125
        }
 
126
}
 
127
 
 
128
void CTR_ModePolicy::CipherResynchronize(byte *keystreamBuffer, const byte *iv, size_t length)
 
129
{
 
130
        assert(length == BlockSize());
 
131
        CopyOrZero(m_register, iv, length);
 
132
        m_counterArray = m_register;
 
133
}
 
134
 
 
135
void BlockOrientedCipherModeBase::UncheckedSetKey(const byte *key, unsigned int length, const NameValuePairs &params)
 
136
{
 
137
        m_cipher->SetKey(key, length, params);
 
138
        ResizeBuffers();
 
139
        if (IsResynchronizable())
 
140
        {
 
141
                size_t ivLength;
 
142
                const byte *iv = GetIVAndThrowIfInvalid(params, ivLength);
 
143
                Resynchronize(iv, (int)ivLength);
 
144
        }
 
145
}
 
146
 
 
147
void ECB_OneWay::ProcessData(byte *outString, const byte *inString, size_t length)
 
148
{
 
149
        assert(length%BlockSize()==0);
 
150
        m_cipher->AdvancedProcessBlocks(inString, NULL, outString, length, 0);
 
151
}
 
152
 
 
153
void CBC_Encryption::ProcessData(byte *outString, const byte *inString, size_t length)
 
154
{
 
155
        if (!length)
 
156
                return;
 
157
        assert(length%BlockSize()==0);
 
158
 
 
159
        unsigned int blockSize = BlockSize();
 
160
        m_cipher->AdvancedProcessBlocks(inString, m_register, outString, blockSize, BlockTransformation::BT_XorInput);
 
161
        if (length > blockSize)
 
162
                m_cipher->AdvancedProcessBlocks(inString+blockSize, outString, outString+blockSize, length-blockSize, BlockTransformation::BT_XorInput);
 
163
        memcpy(m_register, outString + length - blockSize, blockSize);
 
164
}
 
165
 
 
166
void CBC_CTS_Encryption::ProcessLastBlock(byte *outString, const byte *inString, size_t length)
 
167
{
 
168
        if (length <= BlockSize())
 
169
        {
 
170
                if (!m_stolenIV)
 
171
                        throw InvalidArgument("CBC_Encryption: message is too short for ciphertext stealing");
 
172
 
 
173
                // steal from IV
 
174
                memcpy(outString, m_register, length);
 
175
                outString = m_stolenIV;
 
176
        }
 
177
        else
 
178
        {
 
179
                // steal from next to last block
 
180
                xorbuf(m_register, inString, BlockSize());
 
181
                m_cipher->ProcessBlock(m_register);
 
182
                inString += BlockSize();
 
183
                length -= BlockSize();
 
184
                memcpy(outString+BlockSize(), m_register, length);
 
185
        }
 
186
 
 
187
        // output last full ciphertext block
 
188
        xorbuf(m_register, inString, length);
 
189
        m_cipher->ProcessBlock(m_register);
 
190
        memcpy(outString, m_register, BlockSize());
 
191
}
 
192
 
 
193
void CBC_Decryption::ProcessData(byte *outString, const byte *inString, size_t length)
 
194
{
 
195
        if (!length)
 
196
                return;
 
197
        assert(length%BlockSize()==0);
 
198
 
 
199
        unsigned int blockSize = BlockSize();
 
200
        memcpy(m_temp, inString+length-blockSize, blockSize);   // save copy now in case of in-place decryption
 
201
        if (length > blockSize)
 
202
                m_cipher->AdvancedProcessBlocks(inString+blockSize, inString, outString+blockSize, length-blockSize, BlockTransformation::BT_ReverseDirection);
 
203
        m_cipher->ProcessAndXorBlock(inString, m_register, outString);
 
204
        m_register.swap(m_temp);
 
205
}
 
206
 
 
207
void CBC_CTS_Decryption::ProcessLastBlock(byte *outString, const byte *inString, size_t length)
 
208
{
 
209
        const byte *pn, *pn1;
 
210
        bool stealIV = length <= BlockSize();
 
211
 
 
212
        if (stealIV)
 
213
        {
 
214
                pn = inString;
 
215
                pn1 = m_register;
 
216
        }
 
217
        else
 
218
        {
 
219
                pn = inString + BlockSize();
 
220
                pn1 = inString;
 
221
                length -= BlockSize();
 
222
        }
 
223
 
 
224
        // decrypt last partial plaintext block
 
225
        memcpy(m_temp, pn1, BlockSize());
 
226
        m_cipher->ProcessBlock(m_temp);
 
227
        xorbuf(m_temp, pn, length);
 
228
 
 
229
        if (stealIV)
 
230
                memcpy(outString, m_temp, length);
 
231
        else
 
232
        {
 
233
                memcpy(outString+BlockSize(), m_temp, length);
 
234
                // decrypt next to last plaintext block
 
235
                memcpy(m_temp, pn, length);
 
236
                m_cipher->ProcessBlock(m_temp);
 
237
                xorbuf(outString, m_temp, m_register, BlockSize());
 
238
        }
 
239
}
 
240
 
 
241
NAMESPACE_END
 
242
 
 
243
#endif