This library is an implementation of the Secure Hash Algorithm 3 (SHA-3), also known as Keccak. The implementation is constrained to messages with an integral number of octets, i.e. sub-byte length messages are not supported.

NOTE that prior to release 1.0.2 this package had a bug in the generation of message digests where multiple calls to sha3-update with partial buffers could lead to input data being ignored and therefore erroneous message digests being generated. Uses with only one call to sha3-update and the high-level routines were not affected by this bug.

NOTE that prior to release 1.1.0 this package computed digests based on the Keccak submission to the SHA-3 contest and did not yet take into account the added suffix that the FIPS 202 SHA-3 final standard adds to messages prior to calculating the digest, since this was not part of the Keccak submission. Starting with 1.1.0 the functions in the sha3 package do by default calculate disgests that match the FIPS 202 standard, and will calculate the old pre-standard digests only if the new optional keyword argument :raw-keccak-p is passed with a true value.

The code should be portable across nearly all ANSI compliant CL implementations with specialized versions tuned for implementations that offer unboxed 64bit arithmetic, unboxed 32bit arithmetic and for implementations with efficient fixnum arithmetic (requiring fixnums that can represent (unsigned-byte 16)). Especially the 64 and 32bit implementations have been mostly optimized for SBCL and CMU CL. For those implementations, digests with a 1024 bit-rate (and 288 bit digest output) can be generated in between 30 (64bit SBCL) to around 100 (32bit CMU CL) cycles/byte on an i7-640M; whereas optimized C/assembler implementations reach around 12 to 50 cycles/byte on 64/32 bit Intel hardware. The reason for the discrepancy probably lies in missing peephole and dependency optimizations in the SBCL/CMU CL compiler backend.

The mid-level interfaces to the digest routines are the functions

• sha3:sha3-init &key output-bit-length bit-rate

  Create and return a new SHA-3 state. If output-bit-length is specified then the state will run at the bit rate specified for the given output bit length. If output-bit-length is unspecified, bit-rate can be specified to select a suitable bit rate. If both are left unspecified then a default bit rate of 1024 bits is selected, which is suitable for arbitrary output bit lengths of up to 288 bits.

• sha3:sha3-copy state

  Return an independent copy of the SHA-3 state state.

• sha3:sha3-state-p state

  Test whether a given object is a SHA-3 state, i.e. is an instance of the class sha3:sha3-state.

• sha3:sha3-update state vector &key (start 0) (end (length vector))

  Update the given SHA-3 state state from vector, which must be a simple-array with element-type (unsigned-byte 8), bounded by start and end, which must be numeric bounding-indices.

• sha3:sha3-final state &key output-bit-length raw-keccak-p

  If the given SHA-3 state state has not already been finalized, finalize it by processing any remaining input in its buffer, with the specified suffix of 01 and suitable padding as specified by the SHA-3 standard (the specified SHA-3 suffix can be elided with the optional keyword argument raw-keccak-p to generate digests as the initial Keccak submission would have generated). Returns the message digest as a simple-array of (unsigned-byte 8). The length of the returned digest is determined either by the output bit length or bit rate specified on state creation, or for the special case of default parameters being used, by the optional keyword argument output-bit-length. If the state has previously been finalized, the function will return the digest again.

For convenience the following high-level functions produce digests in one step from 1d simple-arrays and streams with element-type (unsigned-byte 8), as well as files:

• sha3:sha3-digest-vector vector &key (start 0) end (output-bit-length 512) raw-keccak-p

  Calculate an SHA-3 message-digest of data in vector, which should be a 1d simple-array with element type (unsigned-byte 8), bounded by start and end. The bit length of the message digest produced is controlled by output-bit-length, which can take on the values 224, 256, 288, 384 and 512, which is the default value. Using the optional raw-keccak-p keyword argument the SHA-3 mandated 01 suffix that is appended to the actual message prior to padding can be elided to yield message digests that match the original Keccak submission instead of the actual SHA-3 standard. Use this option only for compatibility with historical implementations.

• sha3:sha3-digest-stream stream &key (output-bit-length 512) raw-keccak-p

  Calculate an SHA-3 message-digest of data read from stream, which should be a stream with element type (unsigned-byte 8). The bit length of the message digest produced is controlled by output-bit-length, which can take on the values 224, 256, 288, 384 and 512, which is the default value. Using the optional raw-keccak-p keyword argument the SHA-3 mandated 01 suffix that is appended to the actual message prior to padding can be elided to yield message digests that match the original Keccak submission instead of the actual SHA-3 standard. Use this option only for compatibility with historical implementations.

• sha3:sha3-digest-file pathname &key (output-bit-length 512) raw-keccak-p

  Calculate an SHA-3 message-digest of the file specified by pathname. The bit length of the message digest produced is controlled by output-bit-length, which can take on the values 224, 256, 288, 384 and 512, which is the default value. Using the optional raw-keccak-p keyword argument the SHA-3 mandated 01 suffix that is appended to the actual message prior to padding can be elided to yield message digests that match the original Keccak submission instead of the actual SHA-3 standard. Use this option only for compatibility with historical implementations.

Note that in order to generate a message digest of a string it will have to be converted to a simple-array with element-type (unsigned-byte 8) in the proper output-encoding. This will have to rely on implementation-specific functions and is not part of the SHA3 library.

The file keccak-reference.lisp contains a slow simple reference implementation, and testdriver code, which allows testing of the tuned implementations against this reference and against test data available from the Keccak Site at: http://keccak.noekeon.org/KeccakKAT-3.zip

The testcases from the Keccak test data can be run with the following form:

(keccak:test-keccak-msgkat 
 "/Path/To/MsgKatDirectory"
 (lambda (total-bits bit-rate output-bits message)
   (declare (ignore total-bits bit-rate))
   (sha3:sha3-digest-vector message :output-bit-length output-bits :raw-keccak-p t)))

The adapted SHA-3 testcases from the Keccak Code Package test vectors available under https://github.com/gvanas/KeccakCodePackage/tree/master/TestVectors can be run with the following form:

(keccak:test-sha3-msgkat 
 "/Path/To/MsgKatDirectory"
 (lambda (total-bits bit-rate output-bits message)
   (declare (ignore total-bits bit-rate))
   (sha3:sha3-digest-vector message :output-bit-length output-bits)))

This SHA-3 implementation is licensed under the MIT-style license contained in the file COPYING and the header of each source file. Many thanks go to the Keccak Team (Guido Bertoni, Joan Daemen, Michaël Peeters and Gilles Van Assche, cf. http://keccak.team) for their algorithm and excellent documentation and reference implementations.

Please direct any feedback to [email protected]. A git repository of this library is available under git://github.com/pmai/sha3.git