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import json
from calendar import timegm
from collections.abc import Mapping
from datetime import datetime, timedelta
from jose import jws
from .constants import ALGORITHMS
from .exceptions import ExpiredSignatureError, JWSError, JWTClaimsError, JWTError
from .utils import calculate_at_hash, timedelta_total_seconds
def encode(claims, key, algorithm=ALGORITHMS.HS256, headers=None, access_token=None):
"""Encodes a claims set and returns a JWT string.
JWTs are JWS signed objects with a few reserved claims.
Args:
claims (dict): A claims set to sign
key (str or dict): The key to use for signing the claim set. Can be
individual JWK or JWK set.
algorithm (str, optional): The algorithm to use for signing the
the claims. Defaults to HS256.
headers (dict, optional): A set of headers that will be added to
the default headers. Any headers that are added as additional
headers will override the default headers.
access_token (str, optional): If present, the 'at_hash' claim will
be calculated and added to the claims present in the 'claims'
parameter.
Returns:
str: The string representation of the header, claims, and signature.
Raises:
JWTError: If there is an error encoding the claims.
Examples:
>>> jwt.encode({'a': 'b'}, 'secret', algorithm='HS256')
'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJhIjoiYiJ9.jiMyrsmD8AoHWeQgmxZ5yq8z0lXS67_QGs52AzC8Ru8'
"""
for time_claim in ["exp", "iat", "nbf"]:
# Convert datetime to a intDate value in known time-format claims
if isinstance(claims.get(time_claim), datetime):
claims[time_claim] = timegm(claims[time_claim].utctimetuple())
if access_token:
claims["at_hash"] = calculate_at_hash(access_token, ALGORITHMS.HASHES[algorithm])
return jws.sign(claims, key, headers=headers, algorithm=algorithm)
def decode(token, key, algorithms=None, options=None, audience=None, issuer=None, subject=None, access_token=None):
"""Verifies a JWT string's signature and validates reserved claims.
Args:
token (str): A signed JWS to be verified.
key (str or dict): A key to attempt to verify the payload with. Can be
individual JWK or JWK set.
algorithms (str or list): Valid algorithms that should be used to verify the JWS.
audience (str): The intended audience of the token. If the "aud" claim is
included in the claim set, then the audience must be included and must equal
the provided claim.
issuer (str or iterable): Acceptable value(s) for the issuer of the token.
If the "iss" claim is included in the claim set, then the issuer must be
given and the claim in the token must be among the acceptable values.
subject (str): The subject of the token. If the "sub" claim is
included in the claim set, then the subject must be included and must equal
the provided claim.
access_token (str): An access token string. If the "at_hash" claim is included in the
claim set, then the access_token must be included, and it must match
the "at_hash" claim.
options (dict): A dictionary of options for skipping validation steps.
defaults = {
'verify_signature': True,
'verify_aud': True,
'verify_iat': True,
'verify_exp': True,
'verify_nbf': True,
'verify_iss': True,
'verify_sub': True,
'verify_jti': True,
'verify_at_hash': True,
'require_aud': False,
'require_iat': False,
'require_exp': False,
'require_nbf': False,
'require_iss': False,
'require_sub': False,
'require_jti': False,
'require_at_hash': False,
'leeway': 0,
}
Returns:
dict: The dict representation of the claims set, assuming the signature is valid
and all requested data validation passes.
Raises:
JWTError: If the signature is invalid in any way.
ExpiredSignatureError: If the signature has expired.
JWTClaimsError: If any claim is invalid in any way.
Examples:
>>> payload = 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJhIjoiYiJ9.jiMyrsmD8AoHWeQgmxZ5yq8z0lXS67_QGs52AzC8Ru8'
>>> jwt.decode(payload, 'secret', algorithms='HS256')
"""
defaults = {
"verify_signature": True,
"verify_aud": True,
"verify_iat": True,
"verify_exp": True,
"verify_nbf": True,
"verify_iss": True,
"verify_sub": True,
"verify_jti": True,
"verify_at_hash": True,
"require_aud": False,
"require_iat": False,
"require_exp": False,
"require_nbf": False,
"require_iss": False,
"require_sub": False,
"require_jti": False,
"require_at_hash": False,
"leeway": 0,
}
if options:
defaults.update(options)
verify_signature = defaults.get("verify_signature", True)
try:
payload = jws.verify(token, key, algorithms, verify=verify_signature)
except JWSError as e:
raise JWTError(e)
# Needed for at_hash verification
algorithm = jws.get_unverified_header(token)["alg"]
try:
claims = json.loads(payload.decode("utf-8"))
except ValueError as e:
raise JWTError("Invalid payload string: %s" % e)
if not isinstance(claims, Mapping):
raise JWTError("Invalid payload string: must be a json object")
_validate_claims(
claims,
audience=audience,
issuer=issuer,
subject=subject,
algorithm=algorithm,
access_token=access_token,
options=defaults,
)
return claims
def get_unverified_header(token):
"""Returns the decoded headers without verification of any kind.
Args:
token (str): A signed JWT to decode the headers from.
Returns:
dict: The dict representation of the token headers.
Raises:
JWTError: If there is an exception decoding the token.
"""
try:
headers = jws.get_unverified_headers(token)
except Exception:
raise JWTError("Error decoding token headers.")
return headers
def get_unverified_headers(token):
"""Returns the decoded headers without verification of any kind.
This is simply a wrapper of get_unverified_header() for backwards
compatibility.
Args:
token (str): A signed JWT to decode the headers from.
Returns:
dict: The dict representation of the token headers.
Raises:
JWTError: If there is an exception decoding the token.
"""
return get_unverified_header(token)
def get_unverified_claims(token):
"""Returns the decoded claims without verification of any kind.
Args:
token (str): A signed JWT to decode the headers from.
Returns:
dict: The dict representation of the token claims.
Raises:
JWTError: If there is an exception decoding the token.
"""
try:
claims = jws.get_unverified_claims(token)
except Exception:
raise JWTError("Error decoding token claims.")
try:
claims = json.loads(claims.decode("utf-8"))
except ValueError as e:
raise JWTError("Invalid claims string: %s" % e)
if not isinstance(claims, Mapping):
raise JWTError("Invalid claims string: must be a json object")
return claims
def _validate_iat(claims):
"""Validates that the 'iat' claim is valid.
The "iat" (issued at) claim identifies the time at which the JWT was
issued. This claim can be used to determine the age of the JWT. Its
value MUST be a number containing a NumericDate value. Use of this
claim is OPTIONAL.
Args:
claims (dict): The claims dictionary to validate.
"""
if "iat" not in claims:
return
try:
int(claims["iat"])
except ValueError:
raise JWTClaimsError("Issued At claim (iat) must be an integer.")
def _validate_nbf(claims, leeway=0):
"""Validates that the 'nbf' claim is valid.
The "nbf" (not before) claim identifies the time before which the JWT
MUST NOT be accepted for processing. The processing of the "nbf"
claim requires that the current date/time MUST be after or equal to
the not-before date/time listed in the "nbf" claim. Implementers MAY
provide for some small leeway, usually no more than a few minutes, to
account for clock skew. Its value MUST be a number containing a
NumericDate value. Use of this claim is OPTIONAL.
Args:
claims (dict): The claims dictionary to validate.
leeway (int): The number of seconds of skew that is allowed.
"""
if "nbf" not in claims:
return
try:
nbf = int(claims["nbf"])
except ValueError:
raise JWTClaimsError("Not Before claim (nbf) must be an integer.")
now = timegm(datetime.utcnow().utctimetuple())
if nbf > (now + leeway):
raise JWTClaimsError("The token is not yet valid (nbf)")
def _validate_exp(claims, leeway=0):
"""Validates that the 'exp' claim is valid.
The "exp" (expiration time) claim identifies the expiration time on
or after which the JWT MUST NOT be accepted for processing. The
processing of the "exp" claim requires that the current date/time
MUST be before the expiration date/time listed in the "exp" claim.
Implementers MAY provide for some small leeway, usually no more than
a few minutes, to account for clock skew. Its value MUST be a number
containing a NumericDate value. Use of this claim is OPTIONAL.
Args:
claims (dict): The claims dictionary to validate.
leeway (int): The number of seconds of skew that is allowed.
"""
if "exp" not in claims:
return
try:
exp = int(claims["exp"])
except ValueError:
raise JWTClaimsError("Expiration Time claim (exp) must be an integer.")
now = timegm(datetime.utcnow().utctimetuple())
if exp < (now - leeway):
raise ExpiredSignatureError("Signature has expired.")
def _validate_aud(claims, audience=None):
"""Validates that the 'aud' claim is valid.
The "aud" (audience) claim identifies the recipients that the JWT is
intended for. Each principal intended to process the JWT MUST
identify itself with a value in the audience claim. If the principal
processing the claim does not identify itself with a value in the
"aud" claim when this claim is present, then the JWT MUST be
rejected. In the general case, the "aud" value is an array of case-
sensitive strings, each containing a StringOrURI value. In the
special case when the JWT has one audience, the "aud" value MAY be a
single case-sensitive string containing a StringOrURI value. The
interpretation of audience values is generally application specific.
Use of this claim is OPTIONAL.
Args:
claims (dict): The claims dictionary to validate.
audience (str): The audience that is verifying the token.
"""
if "aud" not in claims:
# if audience:
# raise JWTError('Audience claim expected, but not in claims')
return
audience_claims = claims["aud"]
if isinstance(audience_claims, str):
audience_claims = [audience_claims]
if not isinstance(audience_claims, list):
raise JWTClaimsError("Invalid claim format in token")
if any(not isinstance(c, str) for c in audience_claims):
raise JWTClaimsError("Invalid claim format in token")
if audience not in audience_claims:
raise JWTClaimsError("Invalid audience")
def _validate_iss(claims, issuer=None):
"""Validates that the 'iss' claim is valid.
The "iss" (issuer) claim identifies the principal that issued the
JWT. The processing of this claim is generally application specific.
The "iss" value is a case-sensitive string containing a StringOrURI
value. Use of this claim is OPTIONAL.
Args:
claims (dict): The claims dictionary to validate.
issuer (str or iterable): Acceptable value(s) for the issuer that
signed the token.
"""
if issuer is not None:
if isinstance(issuer, str):
issuer = (issuer,)
if claims.get("iss") not in issuer:
raise JWTClaimsError("Invalid issuer")
def _validate_sub(claims, subject=None):
"""Validates that the 'sub' claim is valid.
The "sub" (subject) claim identifies the principal that is the
subject of the JWT. The claims in a JWT are normally statements
about the subject. The subject value MUST either be scoped to be
locally unique in the context of the issuer or be globally unique.
The processing of this claim is generally application specific. The
"sub" value is a case-sensitive string containing a StringOrURI
value. Use of this claim is OPTIONAL.
Args:
claims (dict): The claims dictionary to validate.
subject (str): The subject of the token.
"""
if "sub" not in claims:
return
if not isinstance(claims["sub"], str):
raise JWTClaimsError("Subject must be a string.")
if subject is not None:
if claims.get("sub") != subject:
raise JWTClaimsError("Invalid subject")
def _validate_jti(claims):
"""Validates that the 'jti' claim is valid.
The "jti" (JWT ID) claim provides a unique identifier for the JWT.
The identifier value MUST be assigned in a manner that ensures that
there is a negligible probability that the same value will be
accidentally assigned to a different data object; if the application
uses multiple issuers, collisions MUST be prevented among values
produced by different issuers as well. The "jti" claim can be used
to prevent the JWT from being replayed. The "jti" value is a case-
sensitive string. Use of this claim is OPTIONAL.
Args:
claims (dict): The claims dictionary to validate.
"""
if "jti" not in claims:
return
if not isinstance(claims["jti"], str):
raise JWTClaimsError("JWT ID must be a string.")
def _validate_at_hash(claims, access_token, algorithm):
"""
Validates that the 'at_hash' is valid.
Its value is the base64url encoding of the left-most half of the hash
of the octets of the ASCII representation of the access_token value,
where the hash algorithm used is the hash algorithm used in the alg
Header Parameter of the ID Token's JOSE Header. For instance, if the
alg is RS256, hash the access_token value with SHA-256, then take the
left-most 128 bits and base64url encode them. The at_hash value is a
case sensitive string. Use of this claim is OPTIONAL.
Args:
claims (dict): The claims dictionary to validate.
access_token (str): The access token returned by the OpenID Provider.
algorithm (str): The algorithm used to sign the JWT, as specified by
the token headers.
"""
if "at_hash" not in claims:
return
if not access_token:
msg = "No access_token provided to compare against at_hash claim."
raise JWTClaimsError(msg)
try:
expected_hash = calculate_at_hash(access_token, ALGORITHMS.HASHES[algorithm])
except (TypeError, ValueError):
msg = "Unable to calculate at_hash to verify against token claims."
raise JWTClaimsError(msg)
if claims["at_hash"] != expected_hash:
raise JWTClaimsError("at_hash claim does not match access_token.")
def _validate_claims(claims, audience=None, issuer=None, subject=None, algorithm=None, access_token=None, options=None):
leeway = options.get("leeway", 0)
if isinstance(leeway, timedelta):
leeway = timedelta_total_seconds(leeway)
required_claims = [e[len("require_") :] for e in options.keys() if e.startswith("require_") and options[e]]
for require_claim in required_claims:
if require_claim not in claims:
raise JWTError('missing required key "%s" among claims' % require_claim)
else:
options["verify_" + require_claim] = True # override verify when required
if not isinstance(audience, ((str,), type(None))):
raise JWTError("audience must be a string or None")
if options.get("verify_iat"):
_validate_iat(claims)
if options.get("verify_nbf"):
_validate_nbf(claims, leeway=leeway)
if options.get("verify_exp"):
_validate_exp(claims, leeway=leeway)
if options.get("verify_aud"):
_validate_aud(claims, audience=audience)
if options.get("verify_iss"):
_validate_iss(claims, issuer=issuer)
if options.get("verify_sub"):
_validate_sub(claims, subject=subject)
if options.get("verify_jti"):
_validate_jti(claims)
if options.get("verify_at_hash"):
_validate_at_hash(claims, access_token, algorithm)
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