Botan 1.10.17

cts.cpp
Go to the documentation of this file.
1 /*
2 * CTS Mode
3 * (C) 1999-2007 Jack Lloyd
4 *
5 * Distributed under the terms of the Botan license
6 */
7
8 #include <botan/cts.h>
9 #include <botan/internal/xor_buf.h>
10 #include <algorithm>
11
12 namespace Botan {
13
14 /*
15 * CTS Encryption Constructor
16 */
17 CTS_Encryption::CTS_Encryption(BlockCipher* ciph) :
18 cipher(ciph)
19 {
20 buffer.resize(2 * cipher->block_size());
21 state.resize(cipher->block_size());
22 position = 0;
23 }
24
25 /*
26 * CTS Encryption Constructor
27 */
28 CTS_Encryption::CTS_Encryption(BlockCipher* ciph,
29 const SymmetricKey& key,
30 const InitializationVector& iv) :
31 cipher(ciph)
32 {
33 buffer.resize(2 * cipher->block_size());
34 state.resize(cipher->block_size());
35 position = 0;
36
37 set_key(key);
38 set_iv(iv);
39 }
40
41 /*
42 * Set the IV
43 */
44 void CTS_Encryption::set_iv(const InitializationVector& iv)
45 {
46 if(!valid_iv_length(iv.length()))
47 throw Invalid_IV_Length(name(), iv.length());
48
49 state = iv.bits_of();
50 zeroise(buffer);
51 position = 0;
52 }
53
54 /*
55 * Encrypt a block
56 */
57 void CTS_Encryption::encrypt(const byte block[])
58 {
59 xor_buf(state, block, cipher->block_size());
60 cipher->encrypt(state);
61 send(state, cipher->block_size());
62 }
63
64 /*
65 * Encrypt in CTS mode
66 */
67 void CTS_Encryption::write(const byte input[], size_t length)
68 {
69 size_t copied = std::min<size_t>(buffer.size() - position, length);
70 buffer.copy(position, input, copied);
71 length -= copied;
72 input += copied;
73 position += copied;
74
75 if(length == 0) return;
76
77 encrypt(&buffer[0]);
78 if(length > cipher->block_size())
79 {
80 encrypt(&buffer[cipher->block_size()]);
81 while(length > 2*cipher->block_size())
82 {
83 encrypt(input);
84 length -= cipher->block_size();
85 input += cipher->block_size();
86 }
87 position = 0;
88 }
89 else
90 {
91 copy_mem(&buffer[0], &buffer[cipher->block_size()], cipher->block_size());
92 position = cipher->block_size();
93 }
94 buffer.copy(position, input, length);
95 position += length;
96 }
97
98 /*
99 * Finish encrypting in CTS mode
100 */
101 void CTS_Encryption::end_msg()
102 {
103 if(position < cipher->block_size() + 1)
104 throw Encoding_Error(name() + ": insufficient data to encrypt");
105
106 xor_buf(state, buffer, cipher->block_size());
107 cipher->encrypt(state);
108 SecureVector<byte> cn = state;
109 clear_mem(&buffer[position], buffer.size() - position);
110 encrypt(&buffer[cipher->block_size()]);
111 send(cn, position - cipher->block_size());
112 }
113
114 /*
115 * CTS Decryption Constructor
116 */
117 CTS_Decryption::CTS_Decryption(BlockCipher* ciph) :
118 cipher(ciph)
119 {
120 buffer.resize(2 * cipher->block_size());
121 state.resize(cipher->block_size());
122 temp.resize(cipher->block_size());
123 position = 0;
124 }
125
126 /*
127 * CTS Decryption Constructor
128 */
129 CTS_Decryption::CTS_Decryption(BlockCipher* ciph,
130 const SymmetricKey& key,
131 const InitializationVector& iv) :
132 cipher(ciph)
133 {
134 buffer.resize(2 * cipher->block_size());
135 state.resize(cipher->block_size());
136 temp.resize(cipher->block_size());
137 position = 0;
138
139 set_key(key);
140 set_iv(iv);
141 }
142
143 /*
144 * Set the IV
145 */
146 void CTS_Decryption::set_iv(const InitializationVector& iv)
147 {
148 if(!valid_iv_length(iv.length()))
149 throw Invalid_IV_Length(name(), iv.length());
150
151 state = iv.bits_of();
152 zeroise(buffer);
153 position = 0;
154 }
155
156 /*
157 * Decrypt a block
158 */
159 void CTS_Decryption::decrypt(const byte block[])
160 {
161 cipher->decrypt(block, &temp[0]);
162 xor_buf(temp, state, cipher->block_size());
163 send(temp, cipher->block_size());
164 state.copy(block, cipher->block_size());
165 }
166
167 /*
168 * Decrypt in CTS mode
169 */
170 void CTS_Decryption::write(const byte input[], size_t length)
171 {
172 size_t copied = std::min<size_t>(buffer.size() - position, length);
173 buffer.copy(position, input, copied);
174 length -= copied;
175 input += copied;
176 position += copied;
177
178 if(length == 0) return;
179
180 decrypt(buffer);
181 if(length > cipher->block_size())
182 {
183 decrypt(&buffer[cipher->block_size()]);
184 while(length > 2*cipher->block_size())
185 {
186 decrypt(input);
187 length -= cipher->block_size();
188 input += cipher->block_size();
189 }
190 position = 0;
191 }
192 else
193 {
194 copy_mem(&buffer[0], &buffer[cipher->block_size()], cipher->block_size());
195 position = cipher->block_size();
196 }
197 buffer.copy(position, input, length);
198 position += length;
199 }
200
201 /*
202 * Finish decrypting in CTS mode
203 */
204 void CTS_Decryption::end_msg()
205 {
206 cipher->decrypt(buffer, temp);
207 xor_buf(temp, &buffer[cipher->block_size()], position - cipher->block_size());
208
209 SecureVector<byte> xn = temp;
210
211 copy_mem(&buffer[position],
212 &xn[position - cipher->block_size()],
213 buffer.size() - position);
214
215 cipher->decrypt(&buffer[cipher->block_size()], temp);
216 xor_buf(temp, state, cipher->block_size());
217 send(temp, cipher->block_size());
218 send(xn, position - cipher->block_size());
219 }
220
221 }
Botan::MemoryRegion::resize
void resize(size_t n)
Definition: secmem.h:217
Botan::OctetString
Definition: symkey.h:19
Botan::clear_mem
void clear_mem(T *ptr, size_t n)
Definition: mem_ops.h:32
Botan::Invalid_IV_Length
Definition: exceptn.h:78
Botan::MemoryRegion::copy
void copy(const T in[], size_t n)
Definition: secmem.h:126
Botan::byte
unsigned char byte
Definition: types.h:22
Botan::BlockCipher::decrypt
void decrypt(const byte in[], byte out[]) const
Definition: block_cipher.h:57
Botan::Filter::send
void send(const byte in[], size_t length)
Definition: filter.cpp:28
Botan::CTS_Encryption::set_iv
void set_iv(const InitializationVector &)
Definition: cts.cpp:44
Botan::BlockCipher::encrypt
void encrypt(const byte in[], byte out[]) const
Definition: block_cipher.h:47
Botan::CTS_Decryption::set_key
void set_key(const SymmetricKey &key)
Definition: cts.h:61
Botan::CTS_Encryption::name
std::string name() const
Definition: cts.h:22
Botan::CTS_Encryption::valid_iv_length
bool valid_iv_length(size_t iv_len) const
Definition: cts.h:31
Botan::CTS_Decryption::set_iv
void set_iv(const InitializationVector &)
Definition: cts.cpp:146
Botan::copy_mem
void copy_mem(T *out, const T *in, size_t n)
Definition: mem_ops.h:22
Botan
Definition: algo_base.h:14
Botan::OctetString::length
size_t length() const
Definition: symkey.h:25
Botan::CTS_Encryption::CTS_Encryption
CTS_Encryption(BlockCipher *cipher)
Definition: cts.cpp:17
Botan::CTS_Decryption::CTS_Decryption
CTS_Decryption(BlockCipher *cipher)
Definition: cts.cpp:117
Botan::MemoryRegion::size
size_t size() const
Definition: secmem.h:29
Botan::CTS_Decryption::valid_iv_length
bool valid_iv_length(size_t iv_len) const
Definition: cts.h:66
Botan::OctetString::bits_of
SecureVector< byte > bits_of() const
Definition: symkey.h:30
Botan::xor_buf
void xor_buf(byte out[], const byte in[], size_t length)
Definition: xor_buf.h:21
Botan::CTS_Decryption::name
std::string name() const
Definition: cts.h:57
Botan::zeroise
void zeroise(MemoryRegion< T > &vec)
Definition: secmem.h:428
Botan::BlockCipher::block_size
virtual size_t block_size() const =0
Botan::BlockCipher
Definition: block_cipher.h:18
Botan::CTS_Encryption::set_key
void set_key(const SymmetricKey &key)
Definition: cts.h:26