Hi Jeffrey,

Jeffrey Walton <[email protected]> writes:

> Be careful of truncated hashes. Kelsey showed you cannot simply lop off
> bits and maintain security levels.
>
> The truncated hash use case is one of the use cases handled by SHA3 and the
> extensible output function (XOF). The idea is, different size
> outputs produce completely different hashes under the same input.
>
> For example, these should produce completely unique outputs, and not share
> the same "stem" or leftmost bits.
>
>     $ ./src/cksum -a sha3 -l 224 COPYING
>     SHA3-224 (COPYING) =
> 0e93a263ef507adafd16b2330ba30384c89f56700198efe7b54588a0
>     $ ./src/cksum -a sha3 -l 112 COPYING
>     SHA3-112 (COPYING) = 0e93a263ef507adafd16b2330ba3

Thanks for the input.

Here is the Kelsey presentation just for reference [1].

Collin

[1] 
https://csrc.nist.gov/csrc/media/events/first-cryptographic-hash-workshop/documents/kelsey_truncation.pdf

Reply via email to