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
206
|
using System;
using System.Collections;
using System.IO;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Math.EC;
using Org.BouncyCastle.Security;
using Org.BouncyCastle.Utilities;
using Org.BouncyCastle.Utilities.IO;
namespace Org.BouncyCastle.Crypto.Tls
{
/// <summary>(D)TLS ECDHE key exchange (see RFC 4492).</summary>
public class TlsECDheKeyExchange
: TlsECDHKeyExchange
{
protected TlsSignerCredentials mServerCredentials = null;
public TlsECDheKeyExchange(int keyExchange, IList supportedSignatureAlgorithms, int[] namedCurves,
byte[] clientECPointFormats, byte[] serverECPointFormats)
: base(keyExchange, supportedSignatureAlgorithms, namedCurves, clientECPointFormats, serverECPointFormats)
{
}
public override void ProcessServerCredentials(TlsCredentials serverCredentials)
{
if (!(serverCredentials is TlsSignerCredentials))
throw new TlsFatalAlert(AlertDescription.internal_error);
ProcessServerCertificate(serverCredentials.Certificate);
this.mServerCredentials = (TlsSignerCredentials)serverCredentials;
}
public override byte[] GenerateServerKeyExchange()
{
/*
* First we try to find a supported named curve from the client's list.
*/
int namedCurve = -1;
if (mNamedCurves == null)
{
// TODO Let the peer choose the default named curve
namedCurve = NamedCurve.secp256r1;
}
else
{
for (int i = 0; i < mNamedCurves.Length; ++i)
{
int entry = mNamedCurves[i];
if (NamedCurve.IsValid(entry) && TlsEccUtilities.IsSupportedNamedCurve(entry))
{
namedCurve = entry;
break;
}
}
}
ECDomainParameters curve_params = null;
if (namedCurve >= 0)
{
curve_params = TlsEccUtilities.GetParametersForNamedCurve(namedCurve);
}
else
{
/*
* If no named curves are suitable, check if the client supports explicit curves.
*/
if (Arrays.Contains(mNamedCurves, NamedCurve.arbitrary_explicit_prime_curves))
{
curve_params = TlsEccUtilities.GetParametersForNamedCurve(NamedCurve.secp256r1);
}
else if (Arrays.Contains(mNamedCurves, NamedCurve.arbitrary_explicit_char2_curves))
{
curve_params = TlsEccUtilities.GetParametersForNamedCurve(NamedCurve.sect283r1);
}
}
if (curve_params == null)
{
/*
* NOTE: We shouldn't have negotiated ECDHE key exchange since we apparently can't find
* a suitable curve.
*/
throw new TlsFatalAlert(AlertDescription.internal_error);
}
AsymmetricCipherKeyPair kp = TlsEccUtilities.GenerateECKeyPair(context.SecureRandom, curve_params);
this.mECAgreePrivateKey = (ECPrivateKeyParameters)kp.Private;
DigestInputBuffer buf = new DigestInputBuffer();
if (namedCurve < 0)
{
TlsEccUtilities.WriteExplicitECParameters(mClientECPointFormats, curve_params, buf);
}
else
{
TlsEccUtilities.WriteNamedECParameters(namedCurve, buf);
}
ECPublicKeyParameters ecPublicKey = (ECPublicKeyParameters)kp.Public;
TlsEccUtilities.WriteECPoint(mClientECPointFormats, ecPublicKey.Q, buf);
/*
* RFC 5246 4.7. digitally-signed element needs SignatureAndHashAlgorithm from TLS 1.2
*/
SignatureAndHashAlgorithm signatureAndHashAlgorithm;
IDigest d;
if (TlsUtilities.IsTlsV12(context))
{
signatureAndHashAlgorithm = mServerCredentials.SignatureAndHashAlgorithm;
if (signatureAndHashAlgorithm == null)
throw new TlsFatalAlert(AlertDescription.internal_error);
d = TlsUtilities.CreateHash(signatureAndHashAlgorithm.Hash);
}
else
{
signatureAndHashAlgorithm = null;
d = new CombinedHash();
}
SecurityParameters securityParameters = context.SecurityParameters;
d.BlockUpdate(securityParameters.clientRandom, 0, securityParameters.clientRandom.Length);
d.BlockUpdate(securityParameters.serverRandom, 0, securityParameters.serverRandom.Length);
buf.UpdateDigest(d);
byte[] hash = DigestUtilities.DoFinal(d);
byte[] signature = mServerCredentials.GenerateCertificateSignature(hash);
DigitallySigned signed_params = new DigitallySigned(signatureAndHashAlgorithm, signature);
signed_params.Encode(buf);
return buf.ToArray();
}
public override void ProcessServerKeyExchange(Stream input)
{
SecurityParameters securityParameters = context.SecurityParameters;
SignerInputBuffer buf = new SignerInputBuffer();
Stream teeIn = new TeeInputStream(input, buf);
ECDomainParameters curve_params = TlsEccUtilities.ReadECParameters(mNamedCurves, mClientECPointFormats, teeIn);
byte[] point = TlsUtilities.ReadOpaque8(teeIn);
DigitallySigned signed_params = DigitallySigned.Parse(context, input);
ISigner signer = InitVerifyer(mTlsSigner, signed_params.Algorithm, securityParameters);
buf.UpdateSigner(signer);
if (!signer.VerifySignature(signed_params.Signature))
throw new TlsFatalAlert(AlertDescription.decrypt_error);
this.mECAgreePublicKey = TlsEccUtilities.ValidateECPublicKey(TlsEccUtilities.DeserializeECPublicKey(
mClientECPointFormats, curve_params, point));
}
public override void ValidateCertificateRequest(CertificateRequest certificateRequest)
{
/*
* RFC 4492 3. [...] The ECDSA_fixed_ECDH and RSA_fixed_ECDH mechanisms are usable with
* ECDH_ECDSA and ECDH_RSA. Their use with ECDHE_ECDSA and ECDHE_RSA is prohibited because
* the use of a long-term ECDH client key would jeopardize the forward secrecy property of
* these algorithms.
*/
byte[] types = certificateRequest.CertificateTypes;
for (int i = 0; i < types.Length; ++i)
{
switch (types[i])
{
case ClientCertificateType.rsa_sign:
case ClientCertificateType.dss_sign:
case ClientCertificateType.ecdsa_sign:
break;
default:
throw new TlsFatalAlert(AlertDescription.illegal_parameter);
}
}
}
public override void ProcessClientCredentials(TlsCredentials clientCredentials)
{
if (clientCredentials is TlsSignerCredentials)
{
// OK
}
else
{
throw new TlsFatalAlert(AlertDescription.internal_error);
}
}
protected virtual ISigner InitVerifyer(TlsSigner tlsSigner, SignatureAndHashAlgorithm algorithm,
SecurityParameters securityParameters)
{
ISigner signer = tlsSigner.CreateVerifyer(algorithm, this.mServerPublicKey);
signer.BlockUpdate(securityParameters.clientRandom, 0, securityParameters.clientRandom.Length);
signer.BlockUpdate(securityParameters.serverRandom, 0, securityParameters.serverRandom.Length);
return signer;
}
}
}
|
