chickadee » siphash



A Scheme implementation of the SipHash family of hash functions.

SipHash is a cryptographically strong family of hash functions designed by Jean-Philippe Aumasson and Daniel J. Bernstein.

The source for this extension is available here.


Three functions are provided:

make-siphash c dprocedure

make-siphash constructs a hashing function.

It takes two positive integer arguments c and d and returns a hashing procedure with that many compression and finalization rounds, respectively.

The returned procedure's signature matches those of siphash-2-4 and siphash-4-8.

siphash-2-4 keyprocedure
siphash-2-4 key messageprocedure
siphash-4-8 keyprocedure
siphash-4-8 key messageprocedure

siphash-2-4 and siphash-4-8 are predefined hashing procedures.

Each takes one or two SRFI-4 u8vector arguments, the key and message to hash, and returns a positive integer. key should have a length of 16, while message may be any length. If message isn't given, a prekeyed hashing function is returned.

The SipHash specification recommends SipHash-2-4 for performance and SipHash-4-8 for cryptographic security.


> (define string->u8vector (compose blob->u8vector string->blob))
> (define key (u8vector 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15))
> (define msg (string->u8vector "The rain in Spain falls mainly on the plain."))

> (siphash-2-4 key msg)
; => 8751579407287093977

> ((siphash-4-8 key) msg)
; => 13472556437817646137

> ((make-siphash 8 16)
    "In Hertford, Hereford and Hampshire, hurricanes hardly ever happen."))
; => 9275736844991428064


Evan Hanson



3-Clause BSD

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