max / synckit

Pin the Argon2 serde defaults and the parallelism ceiling The default_argon_* functions are the costs a v1 envelope re-derives under, so assert them against literals rather than against the constants they return. Extend the range test past zero parallelism to 17.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: Max Johnson <me@maxj.phd> · 2026-08-23 21:58 UTC

Signed with PGP, not checked

Commit: a4146a45628f1ddf00bbaca1361a4090aa418333

Parent: 1e82680

1 file changed, +13 insertions, -0 deletions

M synckit-client/src/crypto.rs +13

			@@ -1857,6 +1857,8 @@
1857	1857		// Zero time / parallelism rejected.
1858	1858		assert!(derive_wrapping_key_with_params("pw", &salt, 65_536, 0, 1).is_err());
1859	1859		assert!(derive_wrapping_key_with_params("pw", &salt, 65_536, 3, 0).is_err());
	1860	+	// Inflated parallelism rejected at the ceiling (16), not only at zero.
	1861	+	assert!(derive_wrapping_key_with_params("pw", &salt, 65_536, 3, 17).is_err());
1860	1862		// The pinned production parameters are inside the accepted range.
1861	1863		assert!(
1862	1864		derive_wrapping_key_with_params(
			@@ -1870,6 +1872,17 @@
1870	1872		);
1871	1873		}
1872	1874
	1875	+	/// The serde defaults are what a v1 envelope predating the cost fields
	1876	+	/// re-derives under, so they are wire format. Pinned against literals: an
	1877	+	/// assertion against the constants the functions return would hold however
	1878	+	/// the constants moved.
	1879	+	#[test]
	1880	+	fn argon2_serde_defaults_are_the_pinned_costs() {
	1881	+	assert_eq!(default_argon_mem(), 65_536);
	1882	+	assert_eq!(default_argon_time(), 3);
	1883	+	assert_eq!(default_argon_par(), 1);
	1884	+	}
	1885	+
1873	1886		#[test]
1874	1887		fn blob_total_len_exceeding_input_is_rejected_not_allocated() {
1875	1888		let key = generate_master_key();