GHSA-346h-749j-r28w: PHPECC vulnerable to multiple cryptographic side-channel attacks

ECDSA Canonicalization

PHPECC is vulnerable to malleable ECDSA signature attacks.

Constant-Time Signer

When generating a new ECDSA signature, the GMPMath adapter was used. This class wraps the GNU Multiple Precision arithmetic library (GMP), which does not aim to provide constant-time implementations of algorithms.

An attacker capable of triggering many signatures and studying the time it takes to perform each operation would be able to leak the secret number, k, and thereby learn the private key.

EcDH Timing Leaks

When calculating a shared secret using the EcDH class, the scalar-point multiplication is based on the arithmetic defined by the Point class.

Even though the library implements a Montgomery ladder, the add(), mul(), and getDouble() methods on the Point class are not constant-time. This means that your ECDH private keys are leaking information about each bit of your private key through a timing side-channel.