Function verify 

pub fn verify(msg: &[u8], sig: &[u8; 64], pubkey: &[u8; 32]) -> bool

Verify sig over msg against pubkey. Matches macula_identity:verify/3’s contract exactly: a structurally invalid public key (not a valid Ed25519 point) is treated as “verification failed” (false), not a separate error — it could not have produced a valid signature either way.