# Questions tagged [keccak]

SHA-3, originally known as Keccak, is a cryptographic hash function designed by Guido Bertoni, Joan Daemen, Michaël Peeters, and Gilles Van Assche.

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### Clarification about the iota function of SHA-3

I am trying to implement SHA-3 using this document and have a question about the iota step. This step consists in a single XOR between the central (0, 0) lane of the state (illustration of the state p....
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### Is KMAC just SHA-3-256(KEY || message)

According to keccak strengths you have: Unlike SHA-1 and SHA-2, Keccak does not have the length-extension weakness, hence does not need the HMAC nested construction. Instead, MAC computation can be ...
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### How such so called Merkle pre image are computed?

I’ve just encountered the following source code which is used as an authentication mechanism where the bytes32 leaf is the hashed action to authenticate : ...
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### What are the differences between the various Authenticated Encryption schemes using Keccak?

Keccak - as used in SHA-3 / SHAKE amongst others - can also be used for authenticated encryption. However, there already seem multiple schemes defined for it, including their own implementations: ...
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### Using a bit sequence of zeros followed by one byte in Keccak

For what purpose it is not right to use a bit sequence of 2000+ zeros followed by one byte in Keccak? Is there a possible application of such input for Keccak? If yes, after which transformation?
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### Can a SHA3 engine be used to construct a Keccak implementation?

I am working on a cSHAKE-128 & cSHAKE-256 implementation that takes advantage of a number of hardware accelerators I have at my disposal, specifically for SHA-3 256/384/512 and SHAKE 128/256. ...
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Section B2 of FIPS-202 specification describes the Hexadecimal Form of Padding Bits which is basically the translation of the bit padding 0110*1. However at the beginning they suppose that the message ...
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### Is it possible to create a ciphersuite for TLS 1.3 using only the Keccak-sponge/duplex?

Now that Keccak has been chosen as SHA-3 we see that there have been defined quite a few related modes, including authenticated cipher modes, the KMAC message authentication mode, XOF's and whatnot. ...
181 views

### How does KECCAK operate on a state array filled with zeros?

Im trying to implement a sponge in Java. The state starts out as an empty 200 byte array of all zeros. In the KMAC samples document from NIST, the following happens: (black line is a pdf page break) ...