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JWT support for MicroPython
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import binascii | |
import hashlib | |
import hmac | |
import json | |
from time import time | |
def _to_b64url(data): | |
return ( | |
binascii.b2a_base64(data) | |
.rstrip(b"\n") | |
.rstrip(b"=") | |
.replace(b"+", b"-") | |
.replace(b"/", b"_") | |
) | |
def _from_b64url(data): | |
return binascii.a2b_base64(data.replace(b"-", b"+").replace(b"_", b"/") + b"===") | |
class exceptions: | |
class PyJWTError(Exception): | |
pass | |
class InvalidTokenError(PyJWTError): | |
pass | |
class InvalidAlgorithmError(PyJWTError): | |
pass | |
class InvalidSignatureError(PyJWTError): | |
pass | |
class ExpiredTokenError(PyJWTError): | |
pass | |
def encode(payload, key, algorithm="HS256"): | |
if algorithm != "HS256": | |
raise exceptions.InvalidAlgorithmError() | |
if isinstance(key, str): | |
key = key.encode() | |
header = _to_b64url(json.dumps({"typ": "JWT", "alg": algorithm}).encode()) | |
payload = _to_b64url(json.dumps(payload).encode()) | |
signature = _to_b64url(hmac.new(key, header + b"." + payload, hashlib.sha256).digest()) | |
return (header + b"." + payload + b"." + signature).decode() | |
def decode(token, key, algorithms=["HS256"]): | |
if "HS256" not in algorithms: | |
raise exceptions.InvalidAlgorithmError() | |
parts = token.encode().split(b".") | |
if len(parts) != 3: | |
raise exceptions.InvalidTokenError() | |
header = json.loads(_from_b64url(parts[0]).decode()) | |
payload = json.loads(_from_b64url(parts[1]).decode()) | |
signature = _from_b64url(parts[2]) | |
if header["alg"] not in algorithms or header["alg"] != "HS256": | |
raise exceptions.InvalidAlgorithmError() | |
if isinstance(key, str): | |
key = key.encode() | |
calculated_signature = hmac.new(key, parts[0] + b"." + parts[1], hashlib.sha256).digest() | |
if signature != calculated_signature: | |
raise exceptions.InvalidSignatureError() | |
if "exp" in payload: | |
if time() > payload["exp"]: | |
raise exceptions.ExpiredTokenError() | |
return payload |
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