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
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
|
package org.spongycastle.crypto.tls;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.math.BigInteger;
import java.util.Vector;
import org.spongycastle.asn1.x509.KeyUsage;
import org.spongycastle.asn1.x509.SubjectPublicKeyInfo;
import org.spongycastle.crypto.CryptoException;
import org.spongycastle.crypto.Signer;
import org.spongycastle.crypto.agreement.srp.SRP6Client;
import org.spongycastle.crypto.agreement.srp.SRP6Util;
import org.spongycastle.crypto.digests.SHA1Digest;
import org.spongycastle.crypto.params.AsymmetricKeyParameter;
import org.spongycastle.crypto.util.PublicKeyFactory;
import org.spongycastle.util.BigIntegers;
import org.spongycastle.util.io.TeeInputStream;
/**
* TLS 1.1 SRP key exchange (RFC 5054).
*/
public class TlsSRPKeyExchange extends AbstractTlsKeyExchange
{
protected TlsSigner tlsSigner;
protected byte[] identity;
protected byte[] password;
protected AsymmetricKeyParameter serverPublicKey = null;
protected byte[] s = null;
protected BigInteger B = null;
protected SRP6Client srpClient = new SRP6Client();
public TlsSRPKeyExchange(int keyExchange, Vector supportedSignatureAlgorithms, byte[] identity, byte[] password)
{
super(keyExchange, supportedSignatureAlgorithms);
switch (keyExchange)
{
case KeyExchangeAlgorithm.SRP:
this.tlsSigner = null;
break;
case KeyExchangeAlgorithm.SRP_RSA:
this.tlsSigner = new TlsRSASigner();
break;
case KeyExchangeAlgorithm.SRP_DSS:
this.tlsSigner = new TlsDSSSigner();
break;
default:
throw new IllegalArgumentException("unsupported key exchange algorithm");
}
this.keyExchange = keyExchange;
this.identity = identity;
this.password = password;
}
public void init(TlsContext context)
{
super.init(context);
if (this.tlsSigner != null) {
this.tlsSigner.init(context);
}
}
public void skipServerCredentials() throws IOException
{
if (tlsSigner != null)
{
throw new TlsFatalAlert(AlertDescription.unexpected_message);
}
}
public void processServerCertificate(Certificate serverCertificate) throws IOException
{
if (tlsSigner == null)
{
throw new TlsFatalAlert(AlertDescription.unexpected_message);
}
if (serverCertificate.isEmpty())
{
throw new TlsFatalAlert(AlertDescription.bad_certificate);
}
org.spongycastle.asn1.x509.Certificate x509Cert = serverCertificate.getCertificateAt(0);
SubjectPublicKeyInfo keyInfo = x509Cert.getSubjectPublicKeyInfo();
try
{
this.serverPublicKey = PublicKeyFactory.createKey(keyInfo);
}
catch (RuntimeException e)
{
throw new TlsFatalAlert(AlertDescription.unsupported_certificate);
}
if (!tlsSigner.isValidPublicKey(this.serverPublicKey))
{
throw new TlsFatalAlert(AlertDescription.certificate_unknown);
}
TlsUtils.validateKeyUsage(x509Cert, KeyUsage.digitalSignature);
super.processServerCertificate(serverCertificate);
}
public boolean requiresServerKeyExchange()
{
return true;
}
public void processServerKeyExchange(InputStream input) throws IOException
{
SecurityParameters securityParameters = context.getSecurityParameters();
SignerInputBuffer buf = null;
InputStream teeIn = input;
if (tlsSigner != null)
{
buf = new SignerInputBuffer();
teeIn = new TeeInputStream(input, buf);
}
byte[] NBytes = TlsUtils.readOpaque16(teeIn);
byte[] gBytes = TlsUtils.readOpaque16(teeIn);
byte[] sBytes = TlsUtils.readOpaque8(teeIn);
byte[] BBytes = TlsUtils.readOpaque16(teeIn);
if (buf != null)
{
DigitallySigned signed_params = DigitallySigned.parse(context, input);
Signer signer = initVerifyer(tlsSigner, signed_params.getAlgorithm(), securityParameters);
buf.updateSigner(signer);
if (!signer.verifySignature(signed_params.getSignature()))
{
throw new TlsFatalAlert(AlertDescription.decrypt_error);
}
}
BigInteger N = new BigInteger(1, NBytes);
BigInteger g = new BigInteger(1, gBytes);
// TODO Validate group parameters (see RFC 5054)
// throw new TlsFatalAlert(AlertDescription.insufficient_security);
this.s = sBytes;
/*
* RFC 5054 2.5.3: The client MUST abort the handshake with an "illegal_parameter" alert if
* B % N = 0.
*/
try
{
this.B = SRP6Util.validatePublicValue(N, new BigInteger(1, BBytes));
}
catch (CryptoException e)
{
throw new TlsFatalAlert(AlertDescription.illegal_parameter);
}
this.srpClient.init(N, g, new SHA1Digest(), context.getSecureRandom());
}
public void validateCertificateRequest(CertificateRequest certificateRequest) throws IOException
{
throw new TlsFatalAlert(AlertDescription.unexpected_message);
}
public void processClientCredentials(TlsCredentials clientCredentials) throws IOException
{
throw new TlsFatalAlert(AlertDescription.internal_error);
}
public void generateClientKeyExchange(OutputStream output) throws IOException
{
BigInteger A = srpClient.generateClientCredentials(s, this.identity, this.password);
TlsUtils.writeOpaque16(BigIntegers.asUnsignedByteArray(A), output);
}
public byte[] generatePremasterSecret() throws IOException
{
try
{
// TODO Check if this needs to be a fixed size
return BigIntegers.asUnsignedByteArray(srpClient.calculateSecret(B));
}
catch (CryptoException e)
{
throw new TlsFatalAlert(AlertDescription.illegal_parameter);
}
}
protected Signer initVerifyer(TlsSigner tlsSigner, SignatureAndHashAlgorithm algorithm, SecurityParameters securityParameters)
{
Signer signer = tlsSigner.createVerifyer(algorithm, this.serverPublicKey);
signer.update(securityParameters.clientRandom, 0, securityParameters.clientRandom.length);
signer.update(securityParameters.serverRandom, 0, securityParameters.serverRandom.length);
return signer;
}
}
|
