1package eu.siacs.conversations.crypto.sasl;
2
3import org.bouncycastle.jcajce.provider.digest.SHA256;
4import org.conscrypt.Conscrypt;
5
6import java.security.MessageDigest;
7import java.security.NoSuchAlgorithmException;
8import java.security.cert.Certificate;
9import java.security.cert.CertificateEncodingException;
10import java.security.cert.X509Certificate;
11
12import javax.net.ssl.SSLException;
13import javax.net.ssl.SSLPeerUnverifiedException;
14import javax.net.ssl.SSLSession;
15import javax.net.ssl.SSLSocket;
16
17public interface ChannelBindingMechanism {
18
19 String EXPORTER_LABEL = "EXPORTER-Channel-Binding";
20
21 ChannelBinding getChannelBinding();
22
23 static byte[] getChannelBindingData(final SSLSocket sslSocket, final ChannelBinding channelBinding)
24 throws SaslMechanism.AuthenticationException {
25 if (sslSocket == null) {
26 throw new SaslMechanism.AuthenticationException("Channel binding attempt on non secure socket");
27 }
28 if (channelBinding == ChannelBinding.TLS_EXPORTER) {
29 final byte[] keyingMaterial;
30 try {
31 keyingMaterial =
32 Conscrypt.exportKeyingMaterial(sslSocket, EXPORTER_LABEL, new byte[0], 32);
33 } catch (final SSLException e) {
34 throw new SaslMechanism.AuthenticationException("Could not export keying material");
35 }
36 if (keyingMaterial == null) {
37 throw new SaslMechanism.AuthenticationException(
38 "Could not export keying material. Socket not ready");
39 }
40 return keyingMaterial;
41 } else if (channelBinding == ChannelBinding.TLS_UNIQUE) {
42 final byte[] unique = Conscrypt.getTlsUnique(sslSocket);
43 if (unique == null) {
44 throw new SaslMechanism.AuthenticationException(
45 "Could not retrieve tls unique. Socket not ready");
46 }
47 return unique;
48 } else if (channelBinding == ChannelBinding.TLS_SERVER_END_POINT) {
49 return getServerEndPointChannelBinding(sslSocket.getSession());
50 } else {
51 throw new SaslMechanism.AuthenticationException(
52 String.format("%s is not a valid channel binding", channelBinding));
53 }
54 }
55
56 static byte[] getServerEndPointChannelBinding(final SSLSession session)
57 throws SaslMechanism.AuthenticationException {
58 final Certificate[] certificates;
59 try {
60 certificates = session.getPeerCertificates();
61 } catch (final SSLPeerUnverifiedException e) {
62 throw new SaslMechanism.AuthenticationException("Could not verify peer certificates");
63 }
64 if (certificates == null || certificates.length == 0) {
65 throw new SaslMechanism.AuthenticationException("Could not retrieve peer certificate");
66 }
67 final X509Certificate certificate;
68 if (certificates[0] instanceof X509Certificate) {
69 certificate = (X509Certificate) certificates[0];
70 } else {
71 throw new SaslMechanism.AuthenticationException("Certificate was not X509");
72 }
73 final String algorithm = certificate.getSigAlgName();
74 final int withIndex = algorithm.indexOf("with");
75 if (withIndex <= 0) {
76 throw new SaslMechanism.AuthenticationException("Unable to parse SigAlgName");
77 }
78 final String hashAlgorithm = algorithm.substring(0, withIndex);
79 final MessageDigest messageDigest;
80 // https://www.rfc-editor.org/rfc/rfc5929#section-4.1
81 if ("MD5".equalsIgnoreCase(hashAlgorithm) || "SHA1".equalsIgnoreCase(hashAlgorithm)) {
82 messageDigest = new SHA256.Digest();
83 } else {
84 try {
85 messageDigest = MessageDigest.getInstance(hashAlgorithm);
86 } catch (final NoSuchAlgorithmException e) {
87 throw new SaslMechanism.AuthenticationException(
88 "Could not instantiate message digest for " + hashAlgorithm);
89 }
90 }
91 final byte[] encodedCertificate;
92 try {
93 encodedCertificate = certificate.getEncoded();
94 } catch (final CertificateEncodingException e) {
95 throw new SaslMechanism.AuthenticationException("Could not encode certificate");
96 }
97 messageDigest.update(encodedCertificate);
98 return messageDigest.digest();
99 }
100
101 static int getPriority(final SaslMechanism mechanism) {
102 if (mechanism instanceof ChannelBindingMechanism) {
103 final ChannelBindingMechanism channelBindingMechanism = (ChannelBindingMechanism) mechanism;
104 return ChannelBinding.priority(channelBindingMechanism.getChannelBinding());
105 } else {
106 return 0;
107 }
108 }
109}