certauth/api/signing.py

139 lines
5.8 KiB
Python

import subprocess, datetime, os, hashlib, ipaddress, re
from cryptography import x509
from cryptography.hazmat.primitives import hashes, serialization
from cryptography.hazmat.primitives.asymmetric import ec
from cryptography.x509.oid import NameOID
from config import *
TMP_DIR = "/var/lib/certauth/tmp"
os.makedirs(TMP_DIR, exist_ok=True)
def get_root_pub_key():
with open(YK_PUB_ROOT, "rb") as f:
return serialization.load_pem_public_key(f.read())
def get_int_pub_key():
with open(YK_PUB_INT, "rb") as f:
return serialization.load_pem_public_key(f.read())
def get_root_ca_cert():
with open(ROOT_CA_PATH, "rb") as f:
return x509.load_pem_x509_certificate(f.read())
def der_len(n):
if n < 0x80: return bytes([n])
elif n < 0x100: return bytes([0x81, n])
return bytes([0x82, n>>8, n&0xff])
def sign_tbs_with_yk(tbs_bytes, yk_pin, token_label="certauth Intermediate CA"):
tbs_file = os.path.join(TMP_DIR, "tbs_sign.der")
sig_file = os.path.join(TMP_DIR, "sig_out.bin")
with open(tbs_file, "wb") as f:
f.write(tbs_bytes)
r = subprocess.run([
"sudo", "pkcs11-tool", "--module", PKCS11_MODULE,
"--login", "--pin", yk_pin,
"--sign", "--mechanism", "ECDSA-SHA384",
"--token-label", token_label,
"--label", "SIGN key",
"--input-file", tbs_file,
"--output-file", sig_file
], capture_output=True, text=True)
if r.returncode != 0:
return None, r.stderr
with open(sig_file, "rb") as f:
raw = f.read()
rb = raw[:48].lstrip(b"\x00") or b"\x00"
sb = raw[48:].lstrip(b"\x00") or b"\x00"
if rb[0] & 0x80: rb = b"\x00" + rb
if sb[0] & 0x80: sb = b"\x00" + sb
r_der = b"\x02" + bytes([len(rb)]) + rb
s_der = b"\x02" + bytes([len(sb)]) + sb
seq = b"\x30" + bytes([len(r_der+s_der)]) + r_der + s_der
bs = b"\x00" + seq
return b"\x03" + bytes([len(bs)]) + bs, None
def build_leaf_cert(cn, sans, days=365):
root_cert = get_root_ca_cert()
int_pub = get_int_pub_key()
root_pub = get_root_pub_key()
leaf_key = ec.generate_private_key(ec.SECP384R1())
subject = x509.Name([
x509.NameAttribute(NameOID.COUNTRY_NAME, "US"),
x509.NameAttribute(NameOID.ORGANIZATION_NAME, "Home"),
x509.NameAttribute(NameOID.COMMON_NAME, cn),
])
issuer = x509.Name([
x509.NameAttribute(NameOID.COUNTRY_NAME, "US"),
x509.NameAttribute(NameOID.ORGANIZATION_NAME, "Home"),
x509.NameAttribute(NameOID.COMMON_NAME, "certauth Intermediate CA"),
])
builder = (x509.CertificateBuilder()
.subject_name(subject).issuer_name(issuer)
.public_key(leaf_key.public_key())
.serial_number(x509.random_serial_number())
.not_valid_before(datetime.datetime.now(datetime.timezone.utc))
.not_valid_after(datetime.datetime.now(datetime.timezone.utc) + datetime.timedelta(days=days))
.add_extension(x509.BasicConstraints(ca=False, path_length=None), critical=True)
.add_extension(x509.KeyUsage(
digital_signature=True, key_encipherment=True,
key_cert_sign=False, crl_sign=False,
content_commitment=False, data_encipherment=False,
key_agreement=False, encipher_only=False, decipher_only=False), critical=True)
.add_extension(x509.ExtendedKeyUsage([
x509.oid.ExtendedKeyUsageOID.SERVER_AUTH,
x509.oid.ExtendedKeyUsageOID.CLIENT_AUTH,
]), critical=False)
.add_extension(x509.SubjectKeyIdentifier.from_public_key(leaf_key.public_key()), critical=False)
.add_extension(x509.AuthorityKeyIdentifier.from_issuer_public_key(int_pub), critical=False))
if sans:
san_list = []
for s in sans.split(","):
s = s.strip()
# Check if it's an IP address
if re.match(r"^\d{1,3}(\.\d{1,3}){3}$", s):
san_list.append(x509.IPAddress(ipaddress.ip_address(s)))
else:
san_list.append(x509.DNSName(s))
builder = builder.add_extension(x509.SubjectAlternativeName(san_list), critical=False)
tmp = ec.generate_private_key(ec.SECP384R1())
temp = builder.sign(tmp, hashes.SHA384())
td = temp.public_bytes(serialization.Encoding.DER)
o = 1
if td[o] & 0x80: n = td[o] & 0x7f; o += 1 + n
else: o += 1
tbs_start = o
o += 1
if td[o] & 0x80: n = td[o] & 0x7f; tl = int.from_bytes(td[o+1:o+1+n], "big"); o += 1 + n
else: tl = td[o]; o += 1
tbs_end = o + tl
tbs_full = td[tbs_start:tbs_end]
alg_start = tbs_end
o2 = alg_start + 1
if td[o2] & 0x80: n = td[o2] & 0x7f; al = int.from_bytes(td[o2+1:o2+1+n], "big"); o2 += 1 + n
else: al = td[o2]; o2 += 1
alg_full = td[alg_start:o2+al]
new_sig, err = sign_tbs_with_yk(tbs_full, YK_INT_PIN)
if new_sig is None: return None, err
content = tbs_full + alg_full + new_sig
cl = len(content)
final = b"\x30\x82" + bytes([cl>>8, cl&0xff]) + content
der_file = os.path.join(TMP_DIR, "leaf.der")
pem_file = os.path.join(TMP_DIR, "leaf.pem")
with open(der_file, "wb") as f: f.write(final)
r = subprocess.run(["openssl", "x509", "-inform", "DER", "-outform", "PEM",
"-in", der_file, "-out", pem_file],
capture_output=True, text=True)
if r.returncode != 0: return None, r.stderr
with open(pem_file) as f: leaf_pem = f.read()
key_pem = leaf_key.private_bytes(
encoding=serialization.Encoding.PEM,
format=serialization.PrivateFormat.PKCS8,
encryption_algorithm=serialization.NoEncryption()
).decode()
cert = x509.load_pem_x509_certificate(leaf_pem.encode())
serial = format(cert.serial_number, 'x')
return {"cert_pem": leaf_pem, "key_pem": key_pem, "serial": serial,
"expires_at": cert.not_valid_after.isoformat()}, None