FreeBSD: VID-8FBE81F7-6EB5-11EF-B7BD-00505632D232 (CVE-2024-1544): netatalk3 -- multiple WolfSSL vulnerabilities

Generating the ECDSA nonce k samples a random number r and then

truncates this randomness with a modular reduction mod n where n is the

order of the elliptic curve. Meaning k = r mod n. The division used

during the reduction estimates a factor q_e by dividing the upper two

digits (a digit having e.g. a size of 8 byte) of r by the upper digit of

n and then decrements q_e in a loop until it has the correct size.

Observing the number of times q_e is decremented through a control-flow

revealing side-channel reveals a bias in the most significant bits of

k. Depending on the curve this is either a negligible bias or a

significant bias large enough to reconstruct k with lattice reduction

methods. For SECP160R1, e.g., we find a bias of 15 bits.