[GNU Crypto] FYI: EAX, OMAC

[Casey Marshall]

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I've just checked in implementations of the EAX block cipher mode and
the OMAC message authentication code.

EAX is an authenticating mode, meaning that a MAC is produced at the
end of encipherment, which can be used to verify the integrity of the
ciphertext when decrypted. It is based on CTR mode and OMAC. This also
adds a new interface, IAuthenticatedMode, which is really just the
trivial conjunction of IMode and IMac.

OMAC is a MAC based on a block cipher in CBC mode.

CTR has also been improved to accept block sizes from 1 to the
underlying cipher's block size, and uses the IV parameter as the
initial counter value.

Cheers,

2004-01-19  Casey Marshall  <address@hidden>

        * source/gnu/crypto/mode/ModeFactory.java
        (getInstance): return EAX if requested.

        * source/gnu/crypto/mac/MacFactory.java
        (getInstance): return OMAC if requested.

        * source/gnu/crypto/Registry.java
        (EAX_MODE): new constant.
        (OMAC_PREFIX): new constant.

        * source/gnu/crypto/mode/BaseMode.java
        (testSymmetry): use cipherBlockSize for CIPHER_BLOCK_SIZE.

        * source/gnu/crypto/mode/CTR.java
        (setup): allow smaller block sizes; use IV for initial counter.
        (blockSizes): new method; override default implementation.
        (ctr): modified for varying block sizes.

        * source/gnu/crypto/mode/IAuthenticatedMode.java,
        source/gnu/crypto/mode/EAX.java,
        source/gnu/crypto/mac/OMAC.java,
        source/gnu/testlet/gnu/crypto/mac/TestOfOMAC.java,
        source/gnu/testlet/gnu/crypto/mode/TestOfEAX.java:
        New files.

- -- 
Casey Marshall || address@hidden
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