Clatter has a PSK Validity Rule Violation issue

Impact

Protocol compliance vulnerability. The library allowed post-quantum handshake patterns that violated the PSK validity rule (Noise Protocol Framework Section 9.3). This could allow PSK-derived keys to be used for encryption without proper randomization by self-chosen ephemeral randomness, weakening security guarantees and potentially allowing catastrophic key reuse.

Affected default patterns include noise_pqkk_psk0, noise_pqkn_psk0, noise_pqnk_psk0, noise_pqnn_psk0, and some hybrid variants. Users of these patterns may have been using handshakes that do not meet the intended security properties.

Patches

The issue is fully patched and released in Clatter v2.2.0. The fixed version includes runtime checks to detect offending handshake patterns.

Workarounds

Avoid using offending *_psk0 variants of post-quantum patterns. Review custom handshake patterns carefully.

Resources

• PSK validity rule