From 2d402157d9e6ea34499604455cf1270ef7eb5a1f Mon Sep 17 00:00:00 2001 From: Frank Denis Date: Sat, 22 Aug 2020 14:24:35 +0200 Subject: [PATCH] Improve documentation on siphash recommended parameters --- lib/std/crypto/siphash.zig | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/lib/std/crypto/siphash.zig b/lib/std/crypto/siphash.zig index c4d8735b1c..26c892fdd7 100644 --- a/lib/std/crypto/siphash.zig +++ b/lib/std/crypto/siphash.zig @@ -20,8 +20,10 @@ const mem = std.mem; /// SipHash function with 64-bit output. /// /// Recommended parameters are: +/// - (c_rounds=4, d_rounds=8) for conservative security; regular hash functions such as BLAKE2 or BLAKE3 are usually a better alternative. /// - (c_rounds=2, d_rounds=4) standard parameters. -/// - (c_rounds=1, d_rounds=2) reduced-round function. Faster, no known implications on its practical security level. +/// - (c_rounds=1, d_rounds=3) reduced-round function. Faster, no known implications on its practical security level. +/// - (c_rounds=1, d_rounds=2) fastest option, but the output may be distinguishable from random data with related keys or non-uniform input - not suitable as a PRF. /// /// SipHash is not a traditional hash function. If the input includes untrusted content, a secret key is absolutely necessary. /// And due to its small output size, collisions in SipHash64 can be found with an exhaustive search. @@ -32,8 +34,11 @@ pub fn SipHash64(comptime c_rounds: usize, comptime d_rounds: usize) type { /// SipHash function with 128-bit output. /// /// Recommended parameters are: +/// - (c_rounds=4, d_rounds=8) for conservative security; regular hash functions such as BLAKE2 or BLAKE3 are usually a better alternative. /// - (c_rounds=2, d_rounds=4) standard parameters. -/// - (c_rounds=1, d_rounds=2) reduced-round function. Faster, no known implications on its practical security level. +/// - (c_rounds=1, d_rounds=4) reduced-round function. Recommended to hash very short, similar strings, when a 128-bit PRF output is still required. +/// - (c_rounds=1, d_rounds=3) reduced-round function. Faster, no known implications on its practical security level. +/// - (c_rounds=1, d_rounds=2) fastest option, but the output may be distinguishable from random data with related keys or non-uniform input - not suitable as a PRF. /// /// SipHash is not a traditional hash function. If the input includes untrusted content, a secret key is absolutely necessary. pub fn SipHash128(comptime c_rounds: usize, comptime d_rounds: usize) type {