#!/usr/bin/env python3
"""Generate two cert chains (RSA and EC P-256) for the wo_x509 KAT.
Emits C hex byte arrays: RSA CA + RSA leaf, EC CA + EC leaf."""
import datetime
from cryptography import x509
from cryptography.x509.oid import NameOID
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.asymmetric import rsa, ec, padding
from cryptography.hazmat.primitives.serialization import Encoding

NB = datetime.datetime(2020, 1, 1)
NA = datetime.datetime(2030, 1, 1)

def mkname(cn):
    return x509.Name([x509.NameAttribute(NameOID.COMMON_NAME, cn)])

def selfsigned(key, cn, hashalg, sanhost=None):
    b = (x509.CertificateBuilder()
         .subject_name(mkname(cn)).issuer_name(mkname(cn))
         .public_key(key.public_key())
         .serial_number(x509.random_serial_number())
         .not_valid_before(NB).not_valid_after(NA)
         .add_extension(x509.BasicConstraints(ca=True, path_length=None), True))
    if sanhost:
        b = b.add_extension(x509.SubjectAlternativeName([x509.DNSName(sanhost)]), False)
    return b.sign(key, hashalg)

def leafcert(leafkey, cakey, ca_cert, cn, hashalg, sanhost):
    return (x509.CertificateBuilder()
            .subject_name(mkname(cn)).issuer_name(ca_cert.subject)
            .public_key(leafkey.public_key())
            .serial_number(x509.random_serial_number())
            .not_valid_before(NB).not_valid_after(NA)
            .add_extension(x509.SubjectAlternativeName([x509.DNSName(sanhost)]), False)
            .sign(cakey, hashalg))

def cbytes(name, der):
    out = "static const uint8_t %s[] = {" % name
    for i, b in enumerate(der):
        if i % 12 == 0:
            out += "\n    "
        out += "0x%02x," % b
    out += "\n};\n"
    return out

# RSA chain
rsa_ca_key = rsa.generate_private_key(public_exponent=65537, key_size=2048)
rsa_ca = selfsigned(rsa_ca_key, "wo-rsa-ca", hashes.SHA256())
rsa_leaf_key = rsa.generate_private_key(public_exponent=65537, key_size=2048)
rsa_leaf = leafcert(rsa_leaf_key, rsa_ca_key, rsa_ca, "leaf.example.com",
                    hashes.SHA256(), "leaf.example.com")

# EC chain
ec_ca_key = ec.generate_private_key(ec.SECP256R1())
ec_ca = selfsigned(ec_ca_key, "wo-ec-ca", hashes.SHA256())
ec_leaf_key = ec.generate_private_key(ec.SECP256R1())
ec_leaf = leafcert(ec_leaf_key, ec_ca_key, ec_ca, "leaf.example.org",
                   hashes.SHA256(), "leaf.example.org")

print("/* Generated by scratchpad/gen_x509.py — python cryptography %s.\n"
      " * Two real chains: RSA CA+leaf (SHA256withRSA), EC P-256 CA+leaf\n"
      " * (ecdsa-with-SHA256). Vectors for the wo_x509 phase-E KAT. */" %
      __import__("cryptography").__version__)
print(cbytes("kat_rsa_ca",   rsa_ca.public_bytes(Encoding.DER)))
print(cbytes("kat_rsa_leaf", rsa_leaf.public_bytes(Encoding.DER)))
print(cbytes("kat_ec_ca",    ec_ca.public_bytes(Encoding.DER)))
print(cbytes("kat_ec_leaf",  ec_leaf.public_bytes(Encoding.DER)))