#!/usr/bin/env python3
import argparse, subprocess, json, os, urllib.request, sys, base64, binascii, copy, \
tempfile, re
from urllib.request import urlopen
from urllib.error import HTTPError
def revoke_crt(account_key, crt):
"""Use the ACME protocol to revoke an ssl certificate signed by a
certificate authority.
:param string account_key: Path to your Let's Encrypt account private key.
:param string crt: Path to the signed certificate.
"""
#CA = "https://acme-staging-v02.api.letsencrypt.org"
CA = "https://acme-v02.api.letsencrypt.org"
DIRECTORY = json.loads(urlopen(CA + "/directory").read().decode('utf8'))
def _b64(b):
"Shortcut function to go from bytes to jwt base64 string"
if type(b) is str:
b = b.encode()
return base64.urlsafe_b64encode(b).decode().replace("=", "")
def _a64(a):
"Shortcut function to go from jwt base64 string to bytes"
return base64.urlsafe_b64decode(str(a + ("=" * (len(a) % 4))))
# helper function - run external commands
def _cmd(cmd_list, stdin=None, cmd_input=None, err_msg="Command Line Error"):
proc = subprocess.Popen(cmd_list, stdin=stdin, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
out, err = proc.communicate(cmd_input)
if proc.returncode != 0:
raise IOError("{0}\n{1}".format(err_msg, err))
return out
# helper function - make request and automatically parse json response
def _do_request(url, data=None, err_msg="Error", depth=0):
try:
resp = urllib.request.urlopen(urllib.request.Request(url, data=data, headers={"Content-Type": "application/jose+json", "User-Agent": "acme-nosudo"}))
resp_data, code, headers = resp.read().decode("utf8"), resp.getcode(), resp.headers
except IOError as e:
resp_data = e.read().decode("utf8") if hasattr(e, "read") else str(e)
code, headers = getattr(e, "code", None), {}
try:
resp_data = json.loads(resp_data) # try to parse json results
except ValueError:
pass # ignore json parsing errors
if depth < 100 and code == 400 and resp_data['type'] == "urn:ietf:params:acme:error:badNonce":
raise IndexError(resp_data) # allow 100 retrys for bad nonces
if code not in [200, 201, 204]:
raise ValueError("{0}:\nUrl: {1}\nData: {2}\nResponse Code: {3}\nResponse: {4}".format(err_msg, url, data, code, resp_data))
return resp_data, code, headers
# helper function - make signed requests
def _send_signed_request(url, payload, err_msg, depth=0):
payload64 = "" if payload is None else _b64(json.dumps(payload).encode('utf8'))
new_nonce = _do_request(DIRECTORY['newNonce'])[2]['Replay-Nonce']
protected = {"url": url, "alg": "RS256", "nonce": new_nonce}
protected.update({"jwk": jwk} if acct_headers is None else {"kid": acct_headers['Location']})
protected64 = _b64(json.dumps(protected).encode('utf8'))
protected_input = "{0}.{1}".format(protected64, payload64).encode('utf8')
out = _cmd(["openssl", "dgst", "-sha256", "-sign", account_key], stdin=subprocess.PIPE, cmd_input=protected_input, err_msg="OpenSSL Error")
data = json.dumps({"protected": protected64, "payload": payload64, "signature": _b64(out)})
try:
return _do_request(url, data=data.encode('utf8'), err_msg=err_msg, depth=depth)
except IndexError: # retry bad nonces (they raise IndexError)
return _send_signed_request(url, payload, err_msg, depth=(depth + 1))
# Step 1: Get account public key
sys.stderr.write("Reading pubkey file...\n")
out = _cmd(["openssl", "rsa", "-in", account_key, "-noout", "-text"], err_msg="Error reading account public key")
pub_hex, pub_exp = re.search(
r"modulus:[\s]+?00:([a-f0-9\:\s]+?)\npublicExponent: ([0-9]+)",
out.decode('utf8'), re.MULTILINE|re.DOTALL).groups()
pub_mod = binascii.unhexlify(re.sub("(\s|:)", "", pub_hex))
pub_mod64 = _b64(pub_mod)
pub_exp = int(pub_exp)
pub_exp = "{0:x}".format(pub_exp)
pub_exp = "0{0}".format(pub_exp) if len(pub_exp) % 2 else pub_exp
pub_exp = binascii.unhexlify(pub_exp)
pub_exp64 = _b64(pub_exp)
jwk = {
"e": pub_exp64,
"kty": "RSA",
"n": pub_mod64,
}
sys.stderr.write("Found public key!\n")
# Step 2: Get account info.
sys.stderr.write("Getting account info...\n")
reg = {
"onlyReturnExistiing": True
}
acct_headers = None
result, code, acct_headers = _send_signed_request(DIRECTORY['newAccount'], reg, "Error getting account info")
# Step 3: Generate the payload.
crt_der = _cmd(["openssl", "x509", "-in", crt, "-outform", "DER"], err_msg="DER export error")
crt_der64 = _b64(crt_der)
rvk_payload = {
"certificate": crt_der64,
}
_send_signed_request(DIRECTORY['revokeCert'], rvk_payload, "Error revoking certificate")
sys.stderr.write("Certificate revoked!\n")
if __name__ == "__main__":
parser = argparse.ArgumentParser(
formatter_class=argparse.RawDescriptionHelpFormatter,
description="""\
Get a SSL certificate revoked by a Let's Encrypt (ACME) certificate
authority. You do NOT need to run this script on your server, it is
meant to be run on your computer.
NOTE: YOUR USER KEY NEEDS TO BE THE SAME KEY USED TO ISSUE THE CERTIFICATE.
Prerequisites:
* openssl
* python 3
Example:
--------------
$ python3 revoke_crt.py --account-key user.key domain.crt
--------------
""")
parser.add_argument("-k", "--account-key", required=True, help="path to your Let's Encrypt account private key")
parser.add_argument("crt_path", help="path to your signed certificate")
args = parser.parse_args()
revoke_crt(args.account_key, args.crt_path)
