Add extra logging to troubleshoot issue #670

src/itest/docker-image/Dockerfile

@@ -2,6 +2,8 @@ FROM sickp/alpine-sshd:7.5-r2
 
 ADD authorized_keys /home/sshj/.ssh/authorized_keys
 
+ADD test-container/ssh_host_dsa_key     /etc/ssh/ssh_host_dsa_key
+ADD test-container/ssh_host_dsa_key.pub /etc/ssh/ssh_host_dsa_key.pub
 ADD test-container/ssh_host_ecdsa_key     /etc/ssh/ssh_host_ecdsa_key
 ADD test-container/ssh_host_ecdsa_key.pub /etc/ssh/ssh_host_ecdsa_key.pub
 ADD test-container/ssh_host_ed25519_key   /etc/ssh/ssh_host_ed25519_key
@@ -21,4 +23,4 @@ RUN \
   chmod 644 /etc/ssh/ssh_host_ed25519_key.pub && \
   chown -R sshj:sshj /home/sshj
 
-ENTRYPOINT ["/sbin/tini", "/entrypoint.sh", "-o", "LogLevel=DEBUG2"]
+ENTRYPOINT ["/sbin/tini", "/entrypoint.sh", "-o", "LogLevel=DEBUG2"]

src/itest/docker-image/test-container/ssh_host_dsa_key

@@ -0,0 +1,21 @@
+-----BEGIN OPENSSH PRIVATE KEY-----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+-----END OPENSSH PRIVATE KEY-----

src/itest/docker-image/test-container/ssh_host_dsa_key.pub

@@ -0,0 +1 @@
+ssh-dss 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 ajvanerp@thor

src/itest/docker-image/test-container/sshd_config

@@ -128,9 +128,13 @@ Subsystem	sftp	/usr/lib/ssh/sftp-server
 #	PermitTTY no
 #	ForceCommand cvs server
 
-KexAlgorithms curve25519-sha256,[email protected],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1,diffie-hellman-group-exchange-sha1
-macs [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,[email protected]
+
 
 TrustedUserCAKeys /etc/ssh/users_rsa_ca.pub
 
-Ciphers 3des-cbc,blowfish-cbc,aes128-cbc,aes192-cbc,aes256-cbc,aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected]
+KexAlgorithms +diffie-hellman-group1-sha1,diffie-hellman-group-exchange-sha1
+macs [email protected],hmac-ripemd160,[email protected]
+Ciphers +3des-cbc,blowfish-cbc,aes128-cbc,aes192-cbc,aes256-cbc
+PubKeyAcceptedKeyTypes +ssh-dss
+HostKeyAlgorithms +ssh-dss
+HostbasedAcceptedKeyTypes +ssh-dss

src/itest/groovy/com/hierynomus/sshj/IntegrationSpec.groovy

@@ -16,6 +16,11 @@
 package com.hierynomus.sshj
 
 import com.hierynomus.sshj.key.KeyAlgorithms
+import com.hierynomus.sshj.transport.kex.DHGroups
+import com.hierynomus.sshj.transport.cipher.BlockCiphers
+import com.hierynomus.sshj.transport.mac.Macs
+import net.schmizz.sshj.transport.verification.PromiscuousVerifier
+
 import net.schmizz.sshj.DefaultConfig
 import net.schmizz.sshj.SSHClient
 import net.schmizz.sshj.transport.TransportException
@@ -92,4 +97,22 @@ class IntegrationSpec extends IntegrationBaseSpec {
         thrown(UserAuthException.class)
         !client.isAuthenticated()
     }
+
+    def "should correctly connect using parameters in #670"() {
+        given:
+        def config = new DefaultConfig()
+        // config.setKeyAlgorithms(Collections.singletonList(KeyAlgorithms.SSHDSA())) // Can't get openssh to offer ssh-dss
+        config.setKeyExchangeFactories(DHGroups.Group1SHA1())
+        config.setCipherFactories(BlockCiphers.TripleDESCBC())
+        config.setMACFactories(Macs.HMACSHA1())
+        SSHClient sshClient = new SSHClient(config)
+        sshClient.addHostKeyVerifier(new PromiscuousVerifier())
+
+        when:
+        sshClient.connect(SERVER_IP, DOCKER_PORT)
+
+        then:
+        sshClient.isConnected()
+
+    }
 }

src/main/java/net/schmizz/sshj/transport/Encoder.java

@@ -16,6 +16,7 @@
 package net.schmizz.sshj.transport;
 
 import net.schmizz.sshj.common.Buffer;
+import net.schmizz.sshj.common.ByteArrayUtils;
 import net.schmizz.sshj.common.LoggerFactory;
 import net.schmizz.sshj.common.SSHPacket;
 import net.schmizz.sshj.transport.cipher.Cipher;
@@ -73,7 +74,7 @@ long encode(SSHPacket buffer) {
             }
 
             final int payloadSize = buffer.available();
-            int lengthWithoutPadding;
+            final int lengthWithoutPadding;
             if (etm) {
                 // in Encrypt-Then-Mac mode, the length field is not encrypted, so we should keep it out of the
                 // padding length calculation
@@ -83,18 +84,36 @@ long encode(SSHPacket buffer) {
             }
 
             // Compute padding length
-            int padLen = cipherSize - (lengthWithoutPadding % cipherSize);
-            if (padLen < 4 || (authMode && padLen < cipherSize)) {
-                padLen += cipherSize;
+            // random padding - Arbitrary-length padding, such that the total length of
+            // (packet_length || padding_length || payload || random padding)
+            // is a multiple of the cipher block size or 8, whichever is
+            // larger.  There MUST be at least four bytes of padding.  The
+            // padding SHOULD consist of random bytes.  The maximum amount of
+            // padding is 255 bytes.
+            final int mod = cipherSize > 8 ? cipherSize : 8;
+
+            // (lengthWithoutPadding + padLen) % mod == 0 where 4 <= padLen < 256
+            int padLen = mod - (lengthWithoutPadding % mod);
+            if (padLen < 4 || (authMode && padLen < mod)) {
+                padLen += mod;
             }
 
             final int startOfPacket = buffer.rpos() - 5;
             int packetLen = 1 + payloadSize + padLen; // packetLength = padLen (1 byte) + payload + padding
 
-            if (packetLen < 16) {
-                padLen += cipherSize;
+            // The minimum size of a packet is 16 (or the cipher block size,
+            // whichever is larger) bytes (plus 'mac').  Implementations SHOULD
+            // decrypt the length after receiving the first 8 (or cipher block size,
+            // whichever is larger) bytes of a packet.
+            // if (packetLen < 16) {
+            //     padLen += cipherSize;
+            //     packetLen = 1 + payloadSize + padLen;
+            // }
+            while (packetLen < Math.max(16, cipherSize)) {
+                padLen += mod; // Increment with the mod so that multiple holds
                 packetLen = 1 + payloadSize + padLen;
             }
+
             /*
              * In AES-GCM ciphers, they require packets must be a multiple of 16 bytes (which is also block size of AES)
              * as mentioned in RFC5647 Section 7.2. So we are calculating the extra padding as necessary here
@@ -130,17 +149,23 @@ long encode(SSHPacket buffer) {
                 if (mac != null) {
                     putMAC(buffer, startOfPacket, endOfPadding);
                 }
+
+                if (log.isTraceEnabled()) {
+                    log.trace("Encrypting packet #{}: {}", seq, ByteArrayUtils.printHex(buffer.array(), startOfPacket, 4 + packetLen));
+                }
+
                 cipher.update(buffer.array(), startOfPacket, 4 + packetLen);
             }
             buffer.rpos(startOfPacket); // Make ready-to-read
 
+
             return seq;
         } finally {
             encodeLock.unlock();
         }
     }
 
-    protected void aeadOutgoingBuffer(Buffer buf, int offset, int len) {
+    protected void aeadOutgoingBuffer(Buffer<?> buf, int offset, int len) {
         if (cipher == null || cipher.getAuthenticationTagSize() == 0) {
             throw new IllegalArgumentException("AEAD mode requires an AEAD cipher");
         }