Fix RSA certificate key determination. (#602)

* Fix RSA certificate key determination.

Fixes #599.

* Correct serialization of RSA certificates with unlimited dates.

* The test for connecting with RSA certificate.

* Remove redundant change in TransportImpl.java

* Add forgotten test keys.

* Make net.schmizz.sshj.common.KeyType.CertUtils.epochFromDate readable.

Co-authored-by: Vladimir Lagunov <vladimir.lagunov@jetbrains.com>
Co-authored-by: Jeroen van Erp <jeroen@hierynomus.com>

src/itest/docker-image/Dockerfile

@@ -7,6 +7,7 @@ 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
 ADD test-container/ssh_host_ed25519_key.pub   /etc/ssh/ssh_host_ed25519_key.pub
 ADD test-container/sshd_config /etc/ssh/sshd_config
+ADD test-container/users_rsa_ca.pub /etc/ssh/users_rsa_ca.pub
 
 RUN apk add --no-cache tini
 RUN \
@@ -20,4 +21,4 @@ RUN \
   chmod 644 /etc/ssh/ssh_host_ed25519_key.pub && \
   chown -R sshj:sshj /home/sshj
 
-ENTRYPOINT ["/sbin/tini", "/entrypoint.sh"]
+ENTRYPOINT ["/sbin/tini", "/entrypoint.sh", "-o", "LogLevel=DEBUG2"]

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

@@ -130,3 +130,5 @@ Subsystem	sftp	/usr/lib/ssh/sftp-server
 
 KexAlgorithms curve25519-sha256,curve25519-sha256@libssh.org,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 umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-ripemd160-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,hmac-ripemd160@openssh.com
+
+TrustedUserCAKeys /etc/ssh/users_rsa_ca.pub

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

@@ -0,0 +1 @@
+ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABgQDN70b/cYHZQMD1YW0mlncXqC2l++sEWrVYlIUCzNxNhRYjI4UmEVEq3ru1h6K3ZVAJi1DcZuf5ne1ZXtwJ1Uw1JA4wGdKw+9TwAb5Gubn+VEowgt62kLAPeChiPucTXD0FDDhIUOBv3KxytdrJIYAtzZT27STsBiDF1+7Ld3wk/1Dg9NAaI6q40PmuicTEACQRHn5snI1t9+LgZTd3/PPE5pjJM0ow9+r6mlUUM5oHCk5sZ8DBuRR1Ram4sxp/LFQM+9feMmW3ZM2C5AN0JG4A7NXnlwiTKmNVrGI0iFucBBKhjxN1qdgBF11/42cCrerC9UW1auTTi9mqwEIqBGL30VOPy+dCPQQViP+C09CBgyr3wpZciPKP1mvmcOkC5FDzKg9e3v1JBq0fqZgwt+PPG8cGnxRCGEQ+ZMLDuAixkQUEwDWeMskHLkbjUEiVZydViCPSzFczGtKatQiQVZA5Zx0Gn2sUaQjykhWzqKNL8oIbolEdkH9ubOZWNi0brzU= root@sshj

src/itest/generate.sh

@@ -0,0 +1,6 @@
+#!/bin/sh
+# Don't call it frequently. It's rather a documentation how everything is generated.
+ssh-keygen -f resources/users_rsa_ca -t rsa -N ''
+mv resources/users_rsa_ca.pub docker-image/test-container
+ssh-keygen -f resources/keyfiles/id_rsa2 -t rsa -m pem -N ''
+ssh-keygen -s resources/users_rsa_ca -I my_key_id -n sshj resources/keyfiles/id_rsa2.pub

src/itest/groovy/com/hierynomus/sshj/signature/RsaSignatureClientKeySpec.groovy

@@ -0,0 +1,34 @@
+/*
+ * 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 com.hierynomus.sshj.signature
+
+import com.hierynomus.sshj.IntegrationBaseSpec
+import net.schmizz.sshj.DefaultConfig
+import spock.lang.Unroll
+
+class RsaSignatureClientKeySpec extends IntegrationBaseSpec {
+    @Unroll
+    def "should correctly connect using publickey auth with RSA key with signature"() {
+        given:
+        def client = getConnectedClient(new DefaultConfig())
+
+        when:
+        client.authPublickey(USERNAME, "src/itest/resources/keyfiles/id_rsa2")
+
+        then:
+        client.authenticated
+    }
+}

src/itest/resources/keyfiles/id_rsa2

@@ -0,0 +1,39 @@
+-----BEGIN RSA PRIVATE KEY-----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+-----END RSA PRIVATE KEY-----

src/itest/resources/keyfiles/id_rsa2-cert.pub

@@ -0,0 +1 @@
+ssh-rsa-cert-v01@openssh.com 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 lagunov@unit-1381

src/itest/resources/keyfiles/id_rsa2.pub

@@ -0,0 +1 @@
+ssh-rsa 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 lagunov@unit-1381

src/itest/resources/users_rsa_ca

@@ -0,0 +1,38 @@
+-----BEGIN OPENSSH PRIVATE KEY-----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+-----END OPENSSH PRIVATE KEY-----

src/main/java/net/schmizz/sshj/common/Buffer.java

@@ -58,7 +58,7 @@ public PlainBuffer(int size) {
     public static final int MAX_SIZE = (1 << 30); 
 
     /** Maximum size of a uint64 */
-    private static final BigInteger MAX_UINT64_VALUE = BigInteger.ONE
+    public static final BigInteger MAX_UINT64_VALUE = BigInteger.ONE
                                                             .shiftLeft(64)
                                                             .subtract(BigInteger.ONE);
 

src/main/java/net/schmizz/sshj/common/KeyType.java

@@ -220,6 +220,11 @@ protected void writePubKeyContentsIntoBuffer(PublicKey pk, Buffer<?> buf) {
         protected boolean isMyType(Key key) {
             return CertUtils.isCertificateOfType(key, RSA);
         }
+
+        @Override
+        public KeyType getParent() {
+            return RSA;
+        }
     },
 
     /** Signed dsa certificate */
@@ -239,6 +244,11 @@ protected void writePubKeyContentsIntoBuffer(PublicKey pk, Buffer<?> buf) {
         protected boolean isMyType(Key key) {
             return CertUtils.isCertificateOfType(key, DSA);
         }
+
+        @Override
+        public KeyType getParent() {
+            return KeyType.DSA;
+        }
     },
 
     /** Unrecognized */
@@ -283,10 +293,24 @@ public void putPubKeyIntoBuffer(PublicKey pk, Buffer<?> buf) {
     protected abstract boolean isMyType(Key key);
 
     public static KeyType fromKey(Key key) {
+        KeyType result = UNKNOWN;
         for (KeyType kt : values())
-            if (kt.isMyType((key)))
-                return kt;
-        return UNKNOWN;
+            if (kt.isMyType((key)) && (result == UNKNOWN || kt.isSubType(result)))
+                result = kt;
+        return result;
+    }
+
+    private boolean isSubType(KeyType keyType) {
+        for (KeyType node = this; node != null; node = node.getParent()) {
+            if (keyType == node) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    public KeyType getParent() {
+        return null;
     }
 
     public static KeyType fromString(String sType) {
@@ -372,8 +396,18 @@ private static Date dateFromEpoch(BigInteger seconds) {
             }
         }
 
-        private static long epochFromDate(Date date) {
-            return date.getTime() / 1000;
+        private static BigInteger epochFromDate(Date date) {
+            long time = date.getTime() / 1000;
+            if (time >= Long.MAX_VALUE / 1000) {
+                // Dealing with the signed longs in Java. Since the protocol requires a unix timestamp in milliseconds,
+                // and since Java can store numbers not bigger than 2^63-1 as `long`, we can't distinguish dates
+                // after `new Date(Long.MAX_VALUE / 1000)`. It's unlikely that someone uses certificate valid until
+                // the 10 January of 294247 year. Supposing that such dates are unlimited.
+                // OpenSSH expects to see 0xFF_FF_FF_FF_FF_FF_FF_FF in such cases.
+                return Buffer.MAX_UINT64_VALUE;
+            } else {
+                return BigInteger.valueOf(time);
+            }
         }
 
         private static String unpackString(byte[] packedString) throws BufferException {