Added support for new-style fingerprints (#365)

* Added support for new-style fingerprints

* Fixed codacy warnings

src/main/java/net/schmizz/sshj/SSHClient.java

@@ -38,6 +38,7 @@ import net.schmizz.sshj.transport.compression.DelayedZlibCompression;
 import net.schmizz.sshj.transport.compression.NoneCompression;
 import net.schmizz.sshj.transport.compression.ZlibCompression;
 import net.schmizz.sshj.transport.verification.AlgorithmsVerifier;
+import net.schmizz.sshj.transport.verification.FingerprintVerifier;
 import net.schmizz.sshj.transport.verification.HostKeyVerifier;
 import net.schmizz.sshj.transport.verification.OpenSSHKnownHosts;
 import net.schmizz.sshj.userauth.UserAuth;
@@ -169,19 +170,23 @@ public class SSHClient
 
     /**
      * Add a {@link HostKeyVerifier} that will verify any host that's able to claim a host key with the given {@code
-     * fingerprint}, e.g. {@code "4b:69:6c:72:6f:79:20:77:61:73:20:68:65:72:65:21"}
+     * fingerprint}.
+     *
+     * The fingerprint can be specified in either an MD5 colon-delimited format (16 hexadecimal octets, delimited by a colon),
+     * or in a Base64 encoded format for SHA-1 or SHA-256 fingerprints.
+     * Valid examples are:
+     *
+     * <ul><li>"SHA1:2Fo8c/96zv32xc8GZWbOGYOlRak="</li>
+     * <li>"SHA256:oQGbQTujGeNIgh0ONthcEpA/BHxtt3rcYY+NxXTxQjs="</li>
+     * <li>"MD5:d3:5e:40:72:db:08:f1:6d:0c:d7:6d:35:0d:ba:7c:32"</li>
+     * <li>"d3:5e:40:72:db:08:f1:6d:0c:d7:6d:35:0d:ba:7c:32"</li></ul>
      *
      * @param fingerprint expected fingerprint in colon-delimited format (16 octets in hex delimited by a colon)
      *
      * @see SecurityUtils#getFingerprint
      */
     public void addHostKeyVerifier(final String fingerprint) {
-        addHostKeyVerifier(new HostKeyVerifier() {
-            @Override
-            public boolean verify(String h, int p, PublicKey k) {
-                return SecurityUtils.getFingerprint(k).equals(fingerprint);
-            }
-        });
+        addHostKeyVerifier(FingerprintVerifier.getInstance(fingerprint));
     }
 
     // FIXME: there are way too many auth... overrides. Better API needed.

src/main/java/net/schmizz/sshj/transport/verification/FingerprintVerifier.java

@@ -0,0 +1,124 @@
+/*
+ * Copyright (C)2009 - SSHJ Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package net.schmizz.sshj.transport.verification;
+
+import java.io.IOException;
+import java.security.GeneralSecurityException;
+import java.security.MessageDigest;
+import java.security.PublicKey;
+import java.util.Arrays;
+import java.util.regex.Pattern;
+
+import net.schmizz.sshj.common.Base64;
+import net.schmizz.sshj.common.Buffer;
+import net.schmizz.sshj.common.SSHRuntimeException;
+import net.schmizz.sshj.common.SecurityUtils;
+import net.schmizz.sshj.transport.verification.HostKeyVerifier;
+
+public class FingerprintVerifier implements HostKeyVerifier {
+    private static final Pattern MD5_FINGERPRINT_PATTERN = Pattern.compile("[0-9a-f]{2}+(:[0-9a-f]{2}+){15}+");
+    /**
+     * Valid examples:
+     *
+     * <ul>
+     * <li><code>4b:69:6c:72:6f:79:20:77:61:73:20:68:65:72:65:21</code></li>
+     * <li><code>MD5:4b:69:6c:72:6f:79:20:77:61:73:20:68:65:72:65:21</code></li>
+     * <li><code>SHA1:FghNYu1l/HyE/qWbdQ2mkxrd0rU</code></li>
+     * <li><code>SHA1:FghNYu1l/HyE/qWbdQ2mkxrd0rU=</code></li>
+     * <li><code>SHA256:l/SjyCoKP8jAx3d8k8MWH+UZG0gcuIR7TQRE/A3faQo</code></li>
+     * <li><code>SHA256:l/SjyCoKP8jAx3d8k8MWH+UZG0gcuIR7TQRE/A3faQo=</code></li>
+     * </ul>
+     *
+     *
+     * @param fingerprint of an SSH fingerprint in MD5 (hex), SHA-1 (base64) or SHA-256(base64) format
+     *
+     * @return
+     */
+    public static HostKeyVerifier getInstance(String fingerprint) {
+
+        try {
+            if (fingerprint.startsWith("SHA1:")) {
+                return new FingerprintVerifier("SHA-1", fingerprint.substring(5));
+            }
+
+            if (fingerprint.startsWith("SHA256:")) {
+                return new FingerprintVerifier("SHA-256", fingerprint.substring(7));
+            }
+
+            final String md5;
+            if (fingerprint.startsWith("MD5:")) {
+                md5 = fingerprint.substring(4); // remove the MD5: prefix
+            } else {
+                md5 = fingerprint;
+            }
+
+            if (!MD5_FINGERPRINT_PATTERN.matcher(md5).matches()) {
+                throw new SSHRuntimeException("Invalid MD5 fingerprint: " + fingerprint);
+            }
+
+            // Use the old default fingerprint verifier for md5 fingerprints
+            return (new HostKeyVerifier() {
+                @Override
+                public boolean verify(String h, int p, PublicKey k) {
+                    return SecurityUtils.getFingerprint(k).equals(md5);
+                }
+            });
+        } catch (SSHRuntimeException e) {
+            throw e;
+        } catch (IOException e) {
+            throw new SSHRuntimeException(e);
+        }
+
+    }
+
+    private final String digestAlgorithm;
+    private final byte[] fingerprintData;
+
+    /**
+     *
+     * @param digestAlgorithm
+     *            the used digest algorithm
+     * @param base64Fingerprint
+     *            base64 encoded fingerprint data
+     *
+     * @throws IOException
+     */
+    private FingerprintVerifier(String digestAlgorithm, String base64Fingerprint) throws IOException {
+        this.digestAlgorithm = digestAlgorithm;
+
+        // if the length is not padded with "=" chars at the end so that it is divisible by 4 the SSHJ Base64 implementation does not work correctly
+        StringBuilder base64FingerprintBuilder = new StringBuilder(base64Fingerprint);
+        while (base64FingerprintBuilder.length() % 4 != 0) {
+            base64FingerprintBuilder.append("=");
+        }
+        fingerprintData = Base64.decode(base64FingerprintBuilder.toString());
+    }
+
+    @Override
+    public boolean verify(String hostname, int port, PublicKey key) {
+        MessageDigest digest;
+        try {
+            digest = SecurityUtils.getMessageDigest(digestAlgorithm);
+        } catch (GeneralSecurityException e) {
+            throw new SSHRuntimeException(e);
+        }
+        digest.update(new Buffer.PlainBuffer().putPublicKey(key).getCompactData());
+
+        byte[] digestData = digest.digest();
+        return Arrays.equals(fingerprintData, digestData);
+    }
+
+}

src/test/groovy/net/schmizz/sshj/transport/verification/FingerprintVerifierSpec.groovy

@@ -0,0 +1,58 @@
+/*
+ * Copyright (C)2009 - SSHJ Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package net.schmizz.sshj.transport.verification
+
+import net.schmizz.sshj.common.Base64
+import net.schmizz.sshj.common.Buffer
+import spock.lang.Specification
+import spock.lang.Unroll
+
+class FingerprintVerifierSpec extends Specification {
+
+    @Unroll
+    def "should accept #digest fingerprints"() {
+        given:
+        def verifier = FingerprintVerifier.getInstance(fingerprint)
+        expect:
+        verifier.verify("", 0, getPublicKey())
+        where:
+        digest << ["SHA-1", "SHA-256", "MD5", "old style"]
+        fingerprint << ["SHA1:2Fo8c/96zv32xc8GZWbOGYOlRak=",
+                         "SHA256:oQGbQTujGeNIgh0ONthcEpA/BHxtt3rcYY+NxXTxQjs=",
+                         "MD5:d3:5e:40:72:db:08:f1:6d:0c:d7:6d:35:0d:ba:7c:32",
+                         "d3:5e:40:72:db:08:f1:6d:0c:d7:6d:35:0d:ba:7c:32"]
+    }
+
+    @Unroll
+    def "should accept too short #digest fingerprints"() {
+        given:
+        def verifier = FingerprintVerifier.getInstance(fingerprint)
+        expect:
+        verifier.verify("", 0, getPublicKey())
+        where:
+        digest << ["SHA-1", "SHA-256"]
+        fingerprint << ["SHA1:2Fo8c/96zv32xc8GZWbOGYOlRak",
+                        "SHA256:oQGbQTujGeNIgh0ONthcEpA/BHxtt3rcYY+NxXTxQjs"]
+
+    }
+
+
+    def getPublicKey() {
+        def lines = new File("src/test/resources/keytypes/test_ed25519.pub").readLines()
+        def keystring = lines[0].split(" ")[1]
+        return new Buffer.PlainBuffer(Base64.decode(keystring)).readPublicKey()
+    }
+}