core/src/main/java/org/spongycastle/crypto/tls/DefaultTlsAgreementCredentials.java


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

package org.spongycastle.crypto.tls;

import java.math.BigInteger;

import org.spongycastle.crypto.BasicAgreement;
import org.spongycastle.crypto.agreement.DHBasicAgreement;
import org.spongycastle.crypto.agreement.ECDHBasicAgreement;
import org.spongycastle.crypto.params.AsymmetricKeyParameter;
import org.spongycastle.crypto.params.DHPrivateKeyParameters;
import org.spongycastle.crypto.params.ECPrivateKeyParameters;
import org.spongycastle.util.BigIntegers;

public class DefaultTlsAgreementCredentials
    extends AbstractTlsAgreementCredentials
{
    protected Certificate certificate;
    protected AsymmetricKeyParameter privateKey;

    protected BasicAgreement basicAgreement;
    protected boolean truncateAgreement;

    public DefaultTlsAgreementCredentials(Certificate certificate, AsymmetricKeyParameter privateKey)
    {
        if (certificate == null)
        {
            throw new IllegalArgumentException("'certificate' cannot be null");
        }
        if (certificate.isEmpty())
        {
            throw new IllegalArgumentException("'certificate' cannot be empty");
        }
        if (privateKey == null)
        {
            throw new IllegalArgumentException("'privateKey' cannot be null");
        }
        if (!privateKey.isPrivate())
        {
            throw new IllegalArgumentException("'privateKey' must be private");
        }

        if (privateKey instanceof DHPrivateKeyParameters)
        {
            basicAgreement = new DHBasicAgreement();
            truncateAgreement = true;
        }
        else if (privateKey instanceof ECPrivateKeyParameters)
        {
            basicAgreement = new ECDHBasicAgreement();
            truncateAgreement = false;
        }
        else
        {
            throw new IllegalArgumentException("'privateKey' type not supported: "
                + privateKey.getClass().getName());
        }

        this.certificate = certificate;
        this.privateKey = privateKey;
    }

    public Certificate getCertificate()
    {
        return certificate;
    }

    public byte[] generateAgreement(AsymmetricKeyParameter peerPublicKey)
    {
        basicAgreement.init(privateKey);
        BigInteger agreementValue = basicAgreement.calculateAgreement(peerPublicKey);

        if (truncateAgreement)
        {
            return BigIntegers.asUnsignedByteArray(agreementValue);
        }

        return BigIntegers.asUnsignedByteArray(basicAgreement.getFieldSize(), agreementValue);
    }
}