util_verify

Summary. Verify a cryptographic signature over a payload using a supplied public key. Both secp256k1 and ed25519 signatures are supported; the key type is inferred from the public key using the standard Xahaud convention (an ed25519 public key is 33 bytes prefixed with 0xED; a secp256k1 public key is a 33-byte compressed point).

Signature.

int64_t util_verify(
    uint32_t dread_ptr, uint32_t dread_len,   // signed data (the payload)
    uint32_t sread_ptr, uint32_t sread_len,   // signature
    uint32_t kread_ptr, uint32_t kread_len);  // public key (33 bytes)

Parameters.

Name	Meaning
dread_ptr, dread_len	The message that was signed. Must be non-empty.
sread_ptr, sread_len	The signature bytes. Must be at least 30 bytes.
kread_ptr, kread_len	The public key. Must be exactly 33 bytes and a recognized public-key type.

Return value.

Result	Value	Meaning
valid	1	Signature verifies against the key and data.
invalid	0	Signature does not verify.
OUT_OF_BOUNDS	-1	A region is out of bounds.
INVALID_KEY	-41	kread_len != 33, or the key is not a valid secp256k1/ed25519 public key.
TOO_SMALL	-4	dread_len == 0, or sread_len < 30.

Common failure patterns.

• Passing an uncompressed (65-byte) secp256k1 key → INVALID_KEY; use the 33-byte compressed form.
• Passing an AccountID (20 bytes) as the key → INVALID_KEY. util_verify needs the public key, not the account.
• Confusing "invalid signature" (returns 0, not an error) with an error code: check == 1 for a positive result, and treat negative values as call failures.

Caveats. Signature canonicalization is not enforced by this call (it verifies with mustBeFullyCanonical = false). The function does not hash the data for you — pass the exact bytes that were signed (many Xahau signing schemes sign a prefixed/serialized blob; reproduce that blob before verifying).

Minimal example.

// data, sig, key filled from otxn_param or state
int64_t ok = util_verify(SBUF(data), SBUF(sig), SBUF(pubkey));
if (ok == 1)
    accept(SBUF("signature ok"), 0);
rollback(SBUF("signature invalid"), 1);

Related APIs. util_sha512h (to hash a payload before verifying, if your scheme requires it), otxn_param.