[
https://issues.apache.org/jira/browse/SSHD-506?focusedWorklogId=436573&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-436573
]
ASF GitHub Bot logged work on SSHD-506:
---------------------------------------
Author: ASF GitHub Bot
Created on: 22/May/20 15:58
Start Date: 22/May/20 15:58
Worklog Time Spent: 10m
Work Description: lgoldstein commented on a change in pull request #132:
URL: https://github.com/apache/mina-sshd/pull/132#discussion_r429330029
##########
File path:
sshd-common/src/main/java/org/apache/sshd/common/cipher/BaseGCMCipher.java
##########
@@ -0,0 +1,62 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you 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 org.apache.sshd.common.cipher;
+
+import java.security.spec.AlgorithmParameterSpec;
+
+import javax.crypto.Cipher;
+import javax.crypto.spec.GCMParameterSpec;
+
+import org.apache.sshd.common.util.buffer.Buffer;
+import org.apache.sshd.common.util.buffer.ByteArrayBuffer;
+
+public class BaseGCMCipher extends BaseAEADCipher {
+
+ public BaseGCMCipher(
+ int ivsize, int authSize, int kdfSize, String
algorithm, int keySize, String transformation,
+ int blkSize) {
+ super(ivsize, authSize, kdfSize, algorithm, keySize, transformation,
blkSize);
+ }
+
+ @Override
+ protected AlgorithmParameterSpec initializeAlgorithmParameters(byte[] iv) {
+ Buffer buffer = new ByteArrayBuffer(iv);
+ buffer.rpos(Integer.BYTES);
+ long ic = buffer.getLong();
+ // decrement IV as it will be incremented back to initial value on
first call to updateWithAAD
+ ic = (ic - 1) & 0x0ffffffffL;
+ buffer.wpos(Integer.BYTES);
+ buffer.putLong(ic);
+ return new GCMParameterSpec(getAuthenticationTagSize() * Byte.SIZE,
buffer.array());
+ }
+
+ @Override
+ protected AlgorithmParameterSpec getNextAlgorithmParameters() {
+ Cipher cipher = getCipherInstance();
+ Buffer iv = new ByteArrayBuffer(cipher.getIV());
+ iv.rpos(Integer.BYTES);
+ long ic = iv.getLong();
+ ic = (ic + 1) & 0x0ffffffffL;
+ iv.wpos(Integer.BYTES);
+ iv.putLong(ic);
+ return new GCMParameterSpec(getAuthenticationTagSize() * Byte.SIZE,
iv.array());
+ }
Review comment:
I believe we can avoid creating the `Buffer` since all the code does is
replace an 8-byte section of the IV at offset 4:
```java
byte[] iv = cipher.getIV();
// Need to write decodeLong but it should be similar to decodeInt in the
same class
// can use the code of Buffer#getLong as base
long ic = KeyEntryResolver.decodeLong(iv, Integer.BYTES, iv.length -
Integer.BYTES);
ic = (ic + delta) & 0x0ffffffffL;
// Need to write it - can use the code of Buffer#putLong as base
KeyEntryResolver.encodeLong(iv, ic, Integer.BYTES, iv.length -
Integer.BYTES);
```
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Issue Time Tracking
-------------------
Worklog Id: (was: 436573)
Time Spent: 2h 20m (was: 2h 10m)
> Add support for aes128/256-gcm ciphers
> --------------------------------------
>
> Key: SSHD-506
> URL: https://issues.apache.org/jira/browse/SSHD-506
> Project: MINA SSHD
> Issue Type: Improvement
> Reporter: Lyor Goldstein
> Priority: Major
> Time Spent: 2h 20m
> Remaining Estimate: 0h
>
> See:
> * [rfc5647|https://tools.ietf.org/html/rfc5647]
> *
> [draft-igoe-secsh-aes-gcm-01|https://tools.ietf.org/html/draft-igoe-secsh-aes-gcm-01]
> * [OpenSSH v6.2|http://www.openssh.com/txt/release-6.2]
> * [JAVA AES 256 GCM encrypt/decrypt
> example|https://javainterviewpoint.com/java-aes-256-gcm-encryption-and-decryption/]
> - especially the usage of {{GCMParameterSpec}} to initialize the cipher
> * [OpenJDK 8 AESCipher.java source
> code|https://github.com/frohoff/jdk8u-dev-jdk/blob/master/src/share/classes/com/sun/crypto/provider/AESCipher.java]
> ** See also
> [CipherCore.java|https://github.com/frohoff/jdk8u-dev-jdk/blob/master/src/share/classes/com/sun/crypto/provider/CipherCore.java],
>
> [FeedbackCipher.java|https://github.com/frohoff/jdk8u-dev-jdk/blob/master/src/share/classes/com/sun/crypto/provider/FeedbackCipher.java],
>
> [GaloisCounterMode.java|https://github.com/frohoff/jdk8u-dev-jdk/blob/master/src/share/classes/com/sun/crypto/provider/GaloisCounterMode.java]
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