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
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
|
package org.spongycastle.openpgp.operator.jcajce;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.Provider;
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import org.spongycastle.asn1.nist.NISTNamedCurves;
import org.spongycastle.asn1.x9.X9ECParameters;
import org.spongycastle.bcpg.BCPGKey;
import org.spongycastle.bcpg.ECDHPublicBCPGKey;
import org.spongycastle.bcpg.ECSecretBCPGKey;
import org.spongycastle.bcpg.PublicKeyAlgorithmTags;
import org.spongycastle.bcpg.PublicKeyPacket;
import org.spongycastle.crypto.params.ECDomainParameters;
import org.spongycastle.jcajce.DefaultJcaJceHelper;
import org.spongycastle.jcajce.NamedJcaJceHelper;
import org.spongycastle.jcajce.ProviderJcaJceHelper;
import org.spongycastle.jce.interfaces.ElGamalKey;
import org.spongycastle.math.ec.ECPoint;
import org.spongycastle.openpgp.PGPException;
import org.spongycastle.openpgp.PGPPrivateKey;
import org.spongycastle.openpgp.PGPPublicKey;
import org.spongycastle.openpgp.operator.PGPDataDecryptor;
import org.spongycastle.openpgp.operator.PublicKeyDataDecryptorFactory;
import org.spongycastle.openpgp.operator.RFC6637KDFCalculator;
public class JcePublicKeyDataDecryptorFactoryBuilder
{
private OperatorHelper helper = new OperatorHelper(new DefaultJcaJceHelper());
private OperatorHelper contentHelper = new OperatorHelper(new DefaultJcaJceHelper());
private JcaPGPKeyConverter keyConverter = new JcaPGPKeyConverter();
private JcaPGPDigestCalculatorProviderBuilder digestCalculatorProviderBuilder = new JcaPGPDigestCalculatorProviderBuilder();
private JcaKeyFingerprintCalculator fingerprintCalculator = new JcaKeyFingerprintCalculator();
public JcePublicKeyDataDecryptorFactoryBuilder()
{
}
/**
* Set the provider object to use for creating cryptographic primitives in the resulting factory the builder produces.
*
* @param provider provider object for cryptographic primitives.
* @return the current builder.
*/
public JcePublicKeyDataDecryptorFactoryBuilder setProvider(Provider provider)
{
this.helper = new OperatorHelper(new ProviderJcaJceHelper(provider));
keyConverter.setProvider(provider);
this.contentHelper = helper;
return this;
}
/**
* Set the provider name to use for creating cryptographic primitives in the resulting factory the builder produces.
*
* @param providerName the name of the provider to reference for cryptographic primitives.
* @return the current builder.
*/
public JcePublicKeyDataDecryptorFactoryBuilder setProvider(String providerName)
{
this.helper = new OperatorHelper(new NamedJcaJceHelper(providerName));
keyConverter.setProvider(providerName);
this.contentHelper = helper;
return this;
}
public JcePublicKeyDataDecryptorFactoryBuilder setContentProvider(Provider provider)
{
this.contentHelper = new OperatorHelper(new ProviderJcaJceHelper(provider));
return this;
}
public JcePublicKeyDataDecryptorFactoryBuilder setContentProvider(String providerName)
{
this.contentHelper = new OperatorHelper(new NamedJcaJceHelper(providerName));
return this;
}
public PublicKeyDataDecryptorFactory build(final PrivateKey privKey)
{
return new PublicKeyDataDecryptorFactory()
{
public byte[] recoverSessionData(int keyAlgorithm, byte[][] secKeyData)
throws PGPException
{
if (keyAlgorithm == PublicKeyAlgorithmTags.ECDH)
{
throw new PGPException("ECDH requires use of PGPPrivateKey for decryption");
}
return decryptSessionData(keyAlgorithm, privKey, secKeyData);
}
public PGPDataDecryptor createDataDecryptor(boolean withIntegrityPacket, int encAlgorithm, byte[] key)
throws PGPException
{
return contentHelper.createDataDecryptor(withIntegrityPacket, encAlgorithm, key);
}
};
}
public PublicKeyDataDecryptorFactory build(final PGPPrivateKey privKey)
{
return new PublicKeyDataDecryptorFactory()
{
public byte[] recoverSessionData(int keyAlgorithm, byte[][] secKeyData)
throws PGPException
{
if (keyAlgorithm == PublicKeyAlgorithmTags.ECDH)
{
return decryptSessionData(privKey.getPrivateKeyDataPacket(), privKey.getPublicKeyPacket(), secKeyData);
}
return decryptSessionData(keyAlgorithm, keyConverter.getPrivateKey(privKey), secKeyData);
}
public PGPDataDecryptor createDataDecryptor(boolean withIntegrityPacket, int encAlgorithm, byte[] key)
throws PGPException
{
return contentHelper.createDataDecryptor(withIntegrityPacket, encAlgorithm, key);
}
};
}
private byte[] decryptSessionData(BCPGKey privateKeyPacket, PublicKeyPacket pubKeyData, byte[][] secKeyData)
throws PGPException
{
ECDHPublicBCPGKey ecKey = (ECDHPublicBCPGKey)pubKeyData.getKey();
X9ECParameters x9Params = NISTNamedCurves.getByOID(ecKey.getCurveOID());
ECDomainParameters ecParams = new ECDomainParameters(x9Params.getCurve(), x9Params.getG(), x9Params.getN());
byte[] enc = secKeyData[0];
int pLen = ((((enc[0] & 0xff) << 8) + (enc[1] & 0xff)) + 7) / 8;
byte[] pEnc = new byte[pLen];
System.arraycopy(enc, 2, pEnc, 0, pLen);
byte[] keyEnc = new byte[enc[pLen + 2]];
System.arraycopy(enc, 2 + pLen + 1, keyEnc, 0, keyEnc.length);
Cipher c = helper.createKeyWrapper(ecKey.getSymmetricKeyAlgorithm());
ECPoint S = x9Params.getCurve().decodePoint(pEnc).multiply(((ECSecretBCPGKey)privateKeyPacket).getX()).normalize();
RFC6637KDFCalculator rfc6637KDFCalculator = new RFC6637KDFCalculator(digestCalculatorProviderBuilder.build().get(ecKey.getHashAlgorithm()), ecKey.getSymmetricKeyAlgorithm());
Key key = new SecretKeySpec(rfc6637KDFCalculator.createKey(ecKey.getCurveOID(), S, fingerprintCalculator.calculateFingerprint(pubKeyData)), "AESWrap");
try
{
c.init(Cipher.UNWRAP_MODE, key);
Key paddedSessionKey = c.unwrap(keyEnc, "Session", Cipher.SECRET_KEY);
return PGPUtil.unpadSessionData(paddedSessionKey.getEncoded());
}
catch (InvalidKeyException e)
{
throw new PGPException("error setting asymmetric cipher", e);
}
catch (NoSuchAlgorithmException e)
{
throw new PGPException("error setting asymmetric cipher", e);
}
}
private byte[] decryptSessionData(int keyAlgorithm, PrivateKey privKey, byte[][] secKeyData)
throws PGPException
{
Cipher c1 = helper.createPublicKeyCipher(keyAlgorithm);
try
{
c1.init(Cipher.DECRYPT_MODE, privKey);
}
catch (InvalidKeyException e)
{
throw new PGPException("error setting asymmetric cipher", e);
}
if (keyAlgorithm == PGPPublicKey.RSA_ENCRYPT
|| keyAlgorithm == PGPPublicKey.RSA_GENERAL)
{
byte[] bi = secKeyData[0]; // encoded MPI
c1.update(bi, 2, bi.length - 2);
}
else
{
ElGamalKey k = (ElGamalKey)privKey;
int size = (k.getParameters().getP().bitLength() + 7) / 8;
byte[] tmp = new byte[size];
byte[] bi = secKeyData[0]; // encoded MPI
if (bi.length - 2 > size) // leading Zero? Shouldn't happen but...
{
c1.update(bi, 3, bi.length - 3);
}
else
{
System.arraycopy(bi, 2, tmp, tmp.length - (bi.length - 2), bi.length - 2);
c1.update(tmp);
}
bi = secKeyData[1]; // encoded MPI
for (int i = 0; i != tmp.length; i++)
{
tmp[i] = 0;
}
if (bi.length - 2 > size) // leading Zero? Shouldn't happen but...
{
c1.update(bi, 3, bi.length - 3);
}
else
{
System.arraycopy(bi, 2, tmp, tmp.length - (bi.length - 2), bi.length - 2);
c1.update(tmp);
}
}
try
{
return c1.doFinal();
}
catch (Exception e)
{
throw new PGPException("exception decrypting session data", e);
}
}
}
|
