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
135
136
137
138
139
140
141
142
143
144
|
/*
* Server Key Exchange Message
* (C) 2004-2010,2012 Jack Lloyd
*
* Released under the terms of the Botan license
*/
#include <botan/internal/tls_messages.h>
#include <botan/internal/tls_reader.h>
#include <botan/internal/tls_extensions.h>
#include <botan/pubkey.h>
#include <botan/dh.h>
#include <botan/loadstor.h>
#include <memory>
namespace Botan {
namespace TLS {
/**
* Create a new Server Key Exchange message
*/
Server_Key_Exchange::Server_Key_Exchange(Record_Writer& writer,
Handshake_State* state,
RandomNumberGenerator& rng,
const Private_Key* private_key)
{
const DH_PublicKey* dh_pub = dynamic_cast<const DH_PublicKey*>(state->kex_priv);
if(dh_pub)
{
m_params.push_back(dh_pub->get_domain().get_p());
m_params.push_back(dh_pub->get_domain().get_g());
m_params.push_back(BigInt::decode(dh_pub->public_value()));
}
else
throw Invalid_Argument("Unknown key type " + state->kex_priv->algo_name() +
" for TLS key exchange");
std::pair<std::string, Signature_Format> format =
state->choose_sig_format(private_key, m_hash_algo, m_sig_algo, false);
PK_Signer signer(*private_key, format.first, format.second);
signer.update(state->client_hello->random());
signer.update(state->server_hello->random());
signer.update(serialize_params());
m_signature = signer.signature(rng);
send(writer, state->hash);
}
/**
* Serialize a Server Key Exchange message
*/
MemoryVector<byte> Server_Key_Exchange::serialize() const
{
MemoryVector<byte> buf = serialize_params();
// This should be an explicit version check
if(m_hash_algo != "" && m_sig_algo != "")
{
buf.push_back(Signature_Algorithms::hash_algo_code(m_hash_algo));
buf.push_back(Signature_Algorithms::sig_algo_code(m_sig_algo));
}
append_tls_length_value(buf, m_signature, 2);
return buf;
}
/**
* Serialize the ServerParams structure
*/
MemoryVector<byte> Server_Key_Exchange::serialize_params() const
{
MemoryVector<byte> buf;
for(size_t i = 0; i != m_params.size(); ++i)
append_tls_length_value(buf, BigInt::encode(m_params[i]), 2);
return buf;
}
/**
* Deserialize a Server Key Exchange message
*/
Server_Key_Exchange::Server_Key_Exchange(const MemoryRegion<byte>& buf,
const std::string& kex_algo,
const std::string& sig_algo,
Protocol_Version version)
{
if(buf.size() < 6)
throw Decoding_Error("Server_Key_Exchange: Packet corrupted");
TLS_Data_Reader reader(buf);
if(kex_algo == "DH")
{
// 3 bigints, DH p, g, Y
for(size_t i = 0; i != 3; ++i)
{
BigInt v = BigInt::decode(reader.get_range<byte>(2, 1, 65535));
m_params.push_back(v);
}
}
else
throw Decoding_Error("Unsupported server key exchange type " + kex_algo);
if(sig_algo != "")
{
if(version >= Protocol_Version::TLS_V12)
{
m_hash_algo = Signature_Algorithms::hash_algo_name(reader.get_byte());
m_sig_algo = Signature_Algorithms::sig_algo_name(reader.get_byte());
}
m_signature = reader.get_range<byte>(2, 0, 65535);
}
}
/**
* Verify a Server Key Exchange message
*/
bool Server_Key_Exchange::verify(const X509_Certificate& cert,
Handshake_State* state) const
{
std::auto_ptr<Public_Key> key(cert.subject_public_key());
std::pair<std::string, Signature_Format> format =
state->understand_sig_format(key.get(), m_hash_algo, m_sig_algo, false);
PK_Verifier verifier(*key, format.first, format.second);
verifier.update(state->client_hello->random());
verifier.update(state->server_hello->random());
verifier.update(serialize_params());
return verifier.check_signature(m_signature);
}
}
}
|
