SignatureForge.py

        while True:
            get_context().precision = self.limit_precision(precision)
            attempts += 1
            testPrefix = prefix + urandom(self.keysize_bytes - len(prefix))
            signatureCandidate = (
                toBytes(
                    self.nthroot(
                        self.public_exponent,
                        toInt(testPrefix),
                        self.limit_precision(precision),
                    ),
                    self.keysize_bytes,
                )[: -len(signatureSuffix)]
                + signatureSuffix
            )
            sc = toInt(signatureCandidate)
            p = pow(sc, self.public_exponent)
            pbl = p.bit_length()
            if pbl > self.keysize_bits:
                self.report_small(pbl)
                return None

            toCheck = toBytes(p, (pbl + 7) // 8)
            if 0 not in toCheck[: -len(signatureSuffix)]:
                if progress:
                    if not self.quiet:
                        print("")
                if attempts > 1:
                    if not self.quiet:
                        print("Found in", attempts, "attempt(s)")
                return signatureCandidate