1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
|
/*
* DLIES
* (C) 1999-2007 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/dlies.h>
#include <botan/internal/xor_buf.h>
namespace Botan {
/*
* DLIES_Encryptor Constructor
*/
DLIES_Encryptor::DLIES_Encryptor(const PK_Key_Agreement_Key& key,
KDF* kdf_obj,
MessageAuthenticationCode* mac_obj,
size_t mac_kl) :
ka(key, "Raw"),
kdf(kdf_obj),
mac(mac_obj),
mac_keylen(mac_kl)
{
my_key = key.public_value();
}
/*
* DLIES Encryption
*/
std::vector<byte> DLIES_Encryptor::enc(const byte in[], size_t length,
RandomNumberGenerator&) const
{
if(length > maximum_input_size())
throw Invalid_Argument("DLIES: Plaintext too large");
if(other_key.empty())
throw Invalid_State("DLIES: The other key was never set");
secure_vector<byte> out(my_key.size() + length + mac->output_length());
buffer_insert(out, 0, my_key);
buffer_insert(out, my_key.size(), in, length);
secure_vector<byte> vz(my_key.begin(), my_key.end());
vz += ka.derive_key(0, other_key).bits_of();
const size_t K_LENGTH = length + mac_keylen;
OctetString K = kdf->derive_key(K_LENGTH, vz);
if(K.length() != K_LENGTH)
throw Encoding_Error("DLIES: KDF did not provide sufficient output");
byte* C = &out[my_key.size()];
xor_buf(C, K.begin() + mac_keylen, length);
mac->set_key(K.begin(), mac_keylen);
mac->update(C, length);
for(size_t j = 0; j != 8; ++j)
mac->update(0);
mac->final(C + length);
return unlock(out);
}
/*
* Set the other parties public key
*/
void DLIES_Encryptor::set_other_key(const std::vector<byte>& ok)
{
other_key = ok;
}
/*
* Return the max size, in bytes, of a message
*/
size_t DLIES_Encryptor::maximum_input_size() const
{
return 32;
}
/*
* DLIES_Decryptor Constructor
*/
DLIES_Decryptor::DLIES_Decryptor(const PK_Key_Agreement_Key& key,
KDF* kdf_obj,
MessageAuthenticationCode* mac_obj,
size_t mac_kl) :
ka(key, "Raw"),
kdf(kdf_obj),
mac(mac_obj),
mac_keylen(mac_kl)
{
my_key = key.public_value();
}
/*
* DLIES Decryption
*/
secure_vector<byte> DLIES_Decryptor::dec(const byte msg[], size_t length) const
{
if(length < my_key.size() + mac->output_length())
throw Decoding_Error("DLIES decryption: ciphertext is too short");
const size_t CIPHER_LEN = length - my_key.size() - mac->output_length();
std::vector<byte> v(msg, msg + my_key.size());
secure_vector<byte> C(msg + my_key.size(), msg + my_key.size() + CIPHER_LEN);
secure_vector<byte> T(msg + my_key.size() + CIPHER_LEN,
msg + my_key.size() + CIPHER_LEN + mac->output_length());
secure_vector<byte> vz(msg, msg + my_key.size());
vz += ka.derive_key(0, v).bits_of();
const size_t K_LENGTH = C.size() + mac_keylen;
OctetString K = kdf->derive_key(K_LENGTH, vz);
if(K.length() != K_LENGTH)
throw Encoding_Error("DLIES: KDF did not provide sufficient output");
mac->set_key(K.begin(), mac_keylen);
mac->update(C);
for(size_t j = 0; j != 8; ++j)
mac->update(0);
secure_vector<byte> T2 = mac->final();
if(T != T2)
throw Decoding_Error("DLIES: message authentication failed");
xor_buf(C, K.begin() + mac_keylen, C.size());
return C;
}
}
|
