def main()

in ring/src/rsa/convert_nist_rsa_test_vectors.py [0:0]
58 lines of code
17 McCabe index (conditional complexity)

def main(fn, test_type, padding_alg):
    input_file_digest = hashlib.sha384(open(fn, 'rb').read()).hexdigest()
    # File header
    print("# RSA %(padding_alg)s Test Vectors for FIPS 186-4 from %(fn)s in" % \
            { "fn": fn, "padding_alg": padding_alg })
    print("# http://csrc.nist.gov/groups/STM/cavp/documents/dss/186-3rsatestvectors.zip")
    print("# accessible from")
    print("# http://csrc.nist.gov/groups/STM/cavp/digital-signatures.html#test-vectors")
    print("# with SHA-384 digest %s" % (input_file_digest))
    print("# filtered and reformatted using %s." % __file__)
    print("#")
    print("# Digest = SHAAlg.")
    if test_type == "verify":
        print("# Key is (n, e) encoded in an ASN.1 (DER) sequence.")
    elif test_type == "sign":
        print("# Key is an ASN.1 (DER) RSAPrivateKey.")
    else:
        print("Invalid test_type: %s" % test_type)
        quit()

    print("# Sig = S.")
    print()

    num_cases = 0

    # Each test type has a different field as the last entry per case
    # For verify tests,PKCS "Result" is always the last field.
    # Otherwise, for signing tests, it is dependent on the padding used.
    if test_type == "verify":
        last_field = "Result"
    else:
        if padding_alg == "PSS":
            last_field = "SaltVal"
        else:
            last_field = "S"

    for case in parse(fn, last_field):
        if case['SHAAlg'] == 'SHA224':
            # SHA224 not supported in *ring*.
            debug("Skipping due to use of SHA224", DEBUG)
            continue

        if padding_alg == "PSS":
            if case['SHAAlg'] == 'SHA1':
                # SHA-1 with PSS not supported in *ring*.
                debug("Skipping due to use of SHA1 and PSS.", DEBUG)
                continue

            # *ring* only supports PSS where the salt length is equal to the
            # output length of the hash algorithm.
            if len(case['SaltVal']) * 2 != DIGEST_OUTPUT_LENGTHS[case['SHAAlg']]:
                debug("Skipping due to unsupported salt length.", DEBUG)
                continue

        # Read private key components.
        n = int(case['n'], 16)
        e = int(case['e'], 16)
        d = int(case['d'], 16)

        if test_type == 'sign':
            if n.bit_length() // 8 < 2048 // 8:
                debug("Skipping due to modulus length (too small).", DEBUG)
                continue
            if n.bit_length() > 4096:
                debug("Skipping due to modulus length (too large).", DEBUG)
                continue

            print_sign_test(case, n, e, d, padding_alg)
        else:
            legacy = case['SHAAlg'] in ["SHA1", "SHA256", "SHA512"]
            if (n.bit_length() // 8 < 2048 // 8 and not legacy) or n.bit_length() // 8 < 1024 // 8:
                debug("Skipping due to modulus length (too small).", DEBUG)
                continue
            print_verify_test(case, n, e)

        num_cases += 1

    debug("%d test cases output." % num_cases, True)