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From "Jerry Chen (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HADOOP-11343) Overflow is not properly handled in caclulating final iv for AES CTR
Date Wed, 03 Dec 2014 06:38:15 GMT

     [ https://issues.apache.org/jira/browse/HADOOP-11343?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Jerry Chen updated HADOOP-11343:
--------------------------------
    Status: Patch Available  (was: Open)

The patched is provided. Please help review.

The patch implement calculateIV on 16bytes addition identical to the way underlayer Cipher
uses. This algorithm is modified from BigInteger add algorithm over  an array of ints.

The test cases are provided to guarantee calculateIV algorithm is correct implemented for
designed and random cases.

> Overflow is not properly handled in caclulating final iv for AES CTR
> --------------------------------------------------------------------
>
>                 Key: HADOOP-11343
>                 URL: https://issues.apache.org/jira/browse/HADOOP-11343
>             Project: Hadoop Common
>          Issue Type: Bug
>          Components: security
>    Affects Versions: trunk-win, 2.7.0
>            Reporter: Jerry Chen
>            Assignee: Jerry Chen
>            Priority: Blocker
>         Attachments: HADOOP-11343.patch
>
>
> In the AesCtrCryptoCodec calculateIV, as the init IV is a random generated 16 bytes,

> final byte[] iv = new byte[cc.getCipherSuite().getAlgorithmBlockSize()];
>       cc.generateSecureRandom(iv);
> Then the following calculation of iv and counter on 8 bytes (64bit) space would easily
cause overflow and this overflow gets lost.  The result would be the 128 bit data block was
encrypted with a wrong counter and cannot be decrypted by standard aes-ctr.
> /**
>    * The IV is produced by adding the initial IV to the counter. IV length 
>    * should be the same as {@link #AES_BLOCK_SIZE}
>    */
>   @Override
>   public void calculateIV(byte[] initIV, long counter, byte[] IV) {
>     Preconditions.checkArgument(initIV.length == AES_BLOCK_SIZE);
>     Preconditions.checkArgument(IV.length == AES_BLOCK_SIZE);
>     
>     System.arraycopy(initIV, 0, IV, 0, CTR_OFFSET);
>     long l = 0;
>     for (int i = 0; i < 8; i++) {
>       l = ((l << 8) | (initIV[CTR_OFFSET + i] & 0xff));
>     }
>     l += counter;
>     IV[CTR_OFFSET + 0] = (byte) (l >>> 56);
>     IV[CTR_OFFSET + 1] = (byte) (l >>> 48);
>     IV[CTR_OFFSET + 2] = (byte) (l >>> 40);
>     IV[CTR_OFFSET + 3] = (byte) (l >>> 32);
>     IV[CTR_OFFSET + 4] = (byte) (l >>> 24);
>     IV[CTR_OFFSET + 5] = (byte) (l >>> 16);
>     IV[CTR_OFFSET + 6] = (byte) (l >>> 8);
>     IV[CTR_OFFSET + 7] = (byte) (l);
>   }



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