import json from calendar import timegm try: from collections.abc import Mapping # Python3 except ImportError: from collections import Mapping # Python2, will be deprecated in Python 3.8 from datetime import datetime from datetime import timedelta from six import string_types from jose import jws from .exceptions import JWSError from .exceptions import JWTClaimsError from .exceptions import JWTError from .exceptions import ExpiredSignatureError from .constants import ALGORITHMS from .utils import timedelta_total_seconds, calculate_at_hash 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, string_types): audience_claims = [audience_claims] if not isinstance(audience_claims, list): raise JWTClaimsError('Invalid claim format in token') if any(not isinstance(c, string_types) 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, string_types): 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'], string_types): 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'], string_types): 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) for require_claim in [ e[len("require_"):] for e in options.keys() if e.startswith("require_") and options[e] ]: 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, (string_types, 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)