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I wanted to try new sha3sum so I installed libdigest-sha3-perl on Debian 10. After reading man page I quickly realized that:

sha3sum --algorithm 256 test.txt

produces similar output to sha256sum and that

sha3sum --algorithm 512 test.txt

produces similar output to sha512sum.

But I found two algorithms that don't really make sense to me:

sha3sum --algorithm 128000 test.txt

7f9c2ba4e88f827d616045507605853ed73b8093f6efbc88eb1a6eacfa66ef263cb1eea988004b93103cfb0aeefd2a686e01fa4a58e8a3639ca8a1e3f9ae57e235b8cc873c23dc62b8d260169afa2f75ab916a58d974918835d25e6a435085b2badfd6dfaac359a5efbb7bcc4b59d538df9a04302e10c8bc1cbf1a0b3a5120ea17cda7cfad765f5623474d368ccca8af0007cd9f5e4c849f167a580b14aabdefaee7eef47cb0fca9  test.txt

sha3sum --algorithm 256000 test.txt

46b9dd2b0ba88d13233b3feb743eeb243fcd52ea62b81b82b50c27646ed5762fd75dc4ddd8c0f200cb05019d67b592f6fc821c49479ab48640292eacb3b7c4be141e96616fb13957692cc7edd0b45ae3dc07223c8e92937bef84bc0eab862853349ec75546f58fb7c2775c38462c5010d846c185c15111e595522a6bcd16cf86f3d122109e3b1fdd  test.txt

Could you please tell me what is the point of 128000 and 256000? man page does not say. It doesn't produce 128000 bit output (it's shorter) but even if it did I wonder how useful 128000/256000 bit output would be...

Thank you.

Ben

Ben Hoven
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1 Answers1

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... man page does not say.

It is not in the man page of sha3sum but in the documentation of the module:

Allowed values for $alg are 224, 256, 384, and 512 for the SHA3 algorithms; or 128000 and 256000 for SHAKE128 and SHAKE256, respectively.

Steffen Ullrich
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    Thank you Steffen. I read Keccak Wikipedia page about SHAKE### and thought that it's supposed to be weaker (and faster) then 256 / 512 bits variants. It's interesting that it has longer output... – Ben Hoven Dec 25 '20 at 19:18