Type Definition secp256k1_abc_sys::secp256k1_nonce_function

type secp256k1_nonce_function = Option<unsafe extern "C" fn(nonce32: *mut c_uchar, msg32: *const c_uchar, key32: *const c_uchar, algo16: *const c_uchar, data: *mut c_void, attempt: c_uint) -> c_int>;

A pointer to a function to deterministically generate a nonce.

Returns: 1 if a nonce was successfully generated. 0 will cause signing to fail. Out: nonce32: pointer to a 32-byte array to be filled by the function. In: msg32: the 32-byte message hash being verified (will not be NULL) key32: pointer to a 32-byte secret key (will not be NULL) algo16: pointer to a 16-byte array describing the signature algorithm (will be NULL for ECDSA for compatibility). data: Arbitrary data pointer that is passed through. attempt: how many iterations we have tried to find a nonce. This will almost always be 0, but different attempt values are required to result in a different nonce.

Except for test cases, this function should compute some cryptographic hash of the message, the algorithm, the key and the attempt.