mirror of https://gitlab.com/bashrc2/epicyon
570 lines
23 KiB
Python
570 lines
23 KiB
Python
__filename__ = "httpsig.py"
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__author__ = "Bob Mottram"
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__credits__ = ['lamia']
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__license__ = "AGPL3+"
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__version__ = "1.4.0"
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__maintainer__ = "Bob Mottram"
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__email__ = "bob@libreserver.org"
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__status__ = "Production"
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__module_group__ = "Security"
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# see https://tools.ietf.org/html/draft-cavage-http-signatures-06
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#
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# This might change in future
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# see https://tools.ietf.org/html/draft-ietf-httpbis-message-signatures
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from cryptography.hazmat.backends import default_backend
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from cryptography.hazmat.primitives.serialization import load_pem_private_key
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from cryptography.hazmat.primitives.serialization import load_pem_public_key
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from cryptography.hazmat.primitives.asymmetric import padding
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from cryptography.hazmat.primitives import hashes
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from cryptography.hazmat.primitives.asymmetric import utils as hazutils
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import base64
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from time import gmtime, strftime
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from utils import get_full_domain
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from utils import get_sha_256
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from utils import get_sha_512
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from utils import local_actor_url
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from utils import date_utcnow
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from utils import date_epoch
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from utils import date_from_string_format
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def message_content_digest(message_body_json_str: str,
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digest_algorithm: str) -> str:
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"""Returns the digest for the message body
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"""
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msg = message_body_json_str.encode('utf-8')
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if digest_algorithm in ('rsa-sha512', 'rsa-pss-sha512'):
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hash_result = get_sha_512(msg)
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else:
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hash_result = get_sha_256(msg)
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return base64.b64encode(hash_result).decode('utf-8')
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def get_digest_prefix(digest_algorithm: str) -> str:
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"""Returns the prefix for the message body digest
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"""
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if digest_algorithm in ('rsa-sha512', 'rsa-pss-sha512'):
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return 'SHA-512'
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return 'SHA-256'
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def get_digest_algorithm_from_headers(http_headers: {}) -> str:
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"""Returns the digest algorithm from http headers
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"""
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digest_str = None
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if http_headers.get('digest'):
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digest_str = http_headers['digest']
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elif http_headers.get('Digest'):
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digest_str = http_headers['Digest']
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if digest_str:
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if digest_str.startswith('SHA-512'):
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return 'rsa-sha512'
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return 'rsa-sha256'
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def sign_post_headers(date_str: str, private_key_pem: str,
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nickname: str, domain: str, port: int,
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to_domain: str, to_port: int,
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path: str, http_prefix: str,
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message_body_json_str: str,
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content_type: str, algorithm: str,
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digest_algorithm: str) -> str:
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"""Returns a raw signature string that can be plugged into a header and
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used to verify the authenticity of an HTTP transmission.
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"""
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domain = get_full_domain(domain, port)
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to_domain = get_full_domain(to_domain, to_port)
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if not date_str:
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date_str = strftime("%a, %d %b %Y %H:%M:%S %Z", gmtime())
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if nickname != domain and nickname.lower() != 'actor':
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key_id = local_actor_url(http_prefix, nickname, domain)
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else:
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# instance actor
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key_id = http_prefix + '://' + domain + '/actor'
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key_id += '#main-key'
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if not message_body_json_str:
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headers = {
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'(request-target)': f'get {path}',
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'host': to_domain,
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'date': date_str,
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'accept': content_type
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}
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else:
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body_digest = \
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message_content_digest(message_body_json_str, digest_algorithm)
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digest_prefix = get_digest_prefix(digest_algorithm)
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content_length = len(message_body_json_str)
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headers = {
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'(request-target)': f'post {path}',
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'host': to_domain,
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'date': date_str,
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'digest': f'{digest_prefix}={body_digest}',
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'content-type': 'application/activity+json',
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'content-length': str(content_length)
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}
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key = load_pem_private_key(private_key_pem.encode('utf-8'),
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None, backend=default_backend())
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# headers.update({
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# '(request-target)': f'post {path}',
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# })
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# build a digest for signing
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signed_header_keys = headers.keys()
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signed_header_text = ''
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for header_key in signed_header_keys:
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signed_header_text += f'{header_key}: {headers[header_key]}\n'
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# strip the trailing linefeed
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signed_header_text = signed_header_text.rstrip('\n')
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# signed_header_text.encode('ascii') matches
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try:
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sig_header_encoded = signed_header_text.encode('ascii')
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except UnicodeEncodeError:
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sig_header_encoded = signed_header_text
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print('WARN: sign_post_headers unable to ascii encode ' +
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signed_header_text)
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header_digest = get_sha_256(sig_header_encoded)
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# print('header_digest2: ' + str(header_digest))
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# Sign the digest
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raw_signature = key.sign(header_digest,
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padding.PKCS1v15(),
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hazutils.Prehashed(hashes.SHA256()))
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signature = base64.b64encode(raw_signature).decode('ascii')
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# Put it into a valid HTTP signature format
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signature_dict = {
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'keyId': key_id,
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'algorithm': algorithm,
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'headers': ' '.join(signed_header_keys),
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'signature': signature
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}
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signature_header = ','.join(
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[f'{k}="{v}"' for k, v in signature_dict.items()])
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return signature_header
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def sign_post_headers_new(date_str: str, private_key_pem: str,
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nickname: str,
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domain: str, port: int,
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to_domain: str, to_port: int,
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path: str,
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http_prefix: str,
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message_body_json_str: str,
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algorithm: str, digest_algorithm: str,
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debug: bool) -> (str, str):
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"""Returns a raw signature strings that can be plugged into a header
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as "Signature-Input" and "Signature"
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used to verify the authenticity of an HTTP transmission.
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See https://tools.ietf.org/html/draft-ietf-httpbis-message-signatures
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"""
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domain = get_full_domain(domain, port)
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to_domain = get_full_domain(to_domain, to_port)
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time_format = "%a, %d %b %Y %H:%M:%S %Z"
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if not date_str:
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curr_time = gmtime()
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date_str = strftime(time_format, curr_time)
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else:
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curr_time = date_from_string_format(date_str, [time_format])
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seconds_since_epoch = \
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int((curr_time - date_epoch()).total_seconds())
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key_id = local_actor_url(http_prefix, nickname, domain) + '#main-key'
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if not message_body_json_str:
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headers = {
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'@request-target': f'get {path}',
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'@created': str(seconds_since_epoch),
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'host': to_domain,
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'date': date_str
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}
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else:
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body_digest = message_content_digest(message_body_json_str,
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digest_algorithm)
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digest_prefix = get_digest_prefix(digest_algorithm)
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content_length = len(message_body_json_str)
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headers = {
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'@request-target': f'post {path}',
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'@created': str(seconds_since_epoch),
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'host': to_domain,
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'date': date_str,
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'digest': f'{digest_prefix}={body_digest}',
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'content-type': 'application/activity+json',
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'content-length': str(content_length)
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}
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key = load_pem_private_key(private_key_pem.encode('utf-8'),
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None, backend=default_backend())
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# build a digest for signing
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signed_header_keys = headers.keys()
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signed_header_text = ''
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for header_key in signed_header_keys:
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signed_header_text += f'{header_key}: {headers[header_key]}\n'
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signed_header_text = signed_header_text.strip()
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if debug:
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print('\nsign_post_headers_new signed_header_text:\n' +
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signed_header_text + '\nEND\n')
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# Sign the digest. Potentially other signing algorithms can be added here.
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signature = ''
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if algorithm == 'rsa-sha512':
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header_digest = get_sha_512(signed_header_text.encode('ascii'))
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raw_signature = key.sign(header_digest,
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padding.PKCS1v15(),
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hazutils.Prehashed(hashes.SHA512()))
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signature = base64.b64encode(raw_signature).decode('ascii')
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else:
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# default rsa-sha256
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header_digest = get_sha_256(signed_header_text.encode('ascii'))
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raw_signature = key.sign(header_digest,
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padding.PKCS1v15(),
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hazutils.Prehashed(hashes.SHA256()))
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signature = base64.b64encode(raw_signature).decode('ascii')
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sig_key = 'sig1'
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# Put it into a valid HTTP signature format
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signature_input_dict = {
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'keyId': key_id,
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}
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signature_index_header = '; '.join(
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[f'{k}="{v}"' for k, v in signature_input_dict.items()])
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signature_index_header += '; alg=hs2019'
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signature_index_header += '; created=' + str(seconds_since_epoch)
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signature_index_header += \
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'; ' + sig_key + '=(' + ', '.join(signed_header_keys) + ')'
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signature_dict = {
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sig_key: signature
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}
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signature_header = '; '.join(
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[f'{k}=:{v}:' for k, v in signature_dict.items()])
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return signature_index_header, signature_header
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def create_signed_header(date_str: str, private_key_pem: str, nickname: str,
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domain: str, port: int,
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to_domain: str, to_port: int,
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path: str, http_prefix: str, with_digest: bool,
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message_body_json_str: str,
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content_type: str) -> {}:
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"""Note that the domain is the destination, not the sender
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"""
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algorithm = 'rsa-sha256'
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digest_algorithm = 'rsa-sha256'
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header_domain = get_full_domain(to_domain, to_port)
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# if no date is given then create one
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if not date_str:
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date_str = strftime("%a, %d %b %Y %H:%M:%S %Z", gmtime())
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# Content-Type or Accept header
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if not content_type:
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content_type = 'application/activity+json'
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if not with_digest:
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headers = {
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'(request-target)': f'get {path}',
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'host': header_domain,
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'date': date_str,
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'accept': content_type
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}
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signature_header = \
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sign_post_headers(date_str, private_key_pem, nickname,
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domain, port, to_domain, to_port,
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path, http_prefix, None, content_type,
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algorithm, None)
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else:
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body_digest = message_content_digest(message_body_json_str,
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digest_algorithm)
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digest_prefix = get_digest_prefix(digest_algorithm)
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content_length = len(message_body_json_str)
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headers = {
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'(request-target)': f'post {path}',
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'host': header_domain,
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'date': date_str,
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'digest': f'{digest_prefix}={body_digest}',
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'content-length': str(content_length),
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'content-type': content_type
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}
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signature_header = \
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sign_post_headers(date_str, private_key_pem, nickname,
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domain, port,
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to_domain, to_port,
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path, http_prefix, message_body_json_str,
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content_type, algorithm, digest_algorithm)
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headers['signature'] = signature_header
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return headers
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def _verify_recent_signature(signed_date_str: str) -> bool:
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"""Checks whether the given time taken from the header is within
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12 hours of the current time
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"""
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curr_date = date_utcnow()
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formats = ("%a, %d %b %Y %H:%M:%S %Z",
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"%a, %d %b %Y %H:%M:%S %z")
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signed_date = date_from_string_format(signed_date_str, formats)
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if not signed_date:
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return False
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time_diff_sec = (curr_date - signed_date).total_seconds()
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# 12 hours tollerance
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if time_diff_sec > 43200:
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print('WARN: Header signed too long ago: ' + signed_date_str + ' ' +
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str(time_diff_sec / (60 * 60)) + ' hours')
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return False
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# allow clocks to be off by a few mins
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if time_diff_sec < -480:
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print('WARN: Header signed in the future! ' + signed_date_str + ' ' +
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str(time_diff_sec / (60 * 60)) + ' hours')
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return False
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return True
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def verify_post_headers(http_prefix: str,
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public_key_pem: str, headers: dict,
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path: str, get_method: bool,
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message_body_digest: str,
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message_body_json_str: str, debug: bool,
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no_recency_check: bool = False) -> bool:
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"""Returns true or false depending on if the key that we plugged in here
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validates against the headers, method, and path.
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public_key_pem - the public key from an rsa key pair
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headers - should be a dictionary of request headers
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path - the relative url that was requested from this site
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get_method - GET or POST
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message_body_json_str - the received request body (used for digest)
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"""
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if get_method:
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method = 'GET'
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else:
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method = 'POST'
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if debug:
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print('DEBUG: verify_post_headers ' + method)
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print('verify_post_headers public_key_pem: ' + str(public_key_pem))
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print('verify_post_headers headers: ' + str(headers))
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print('verify_post_headers message_body_json_str: ' +
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str(message_body_json_str))
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pubkey = load_pem_public_key(public_key_pem.encode('utf-8'),
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backend=default_backend())
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# Build a dictionary of the signature values
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if headers.get('Signature-Input') or headers.get('signature-input'):
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if headers.get('Signature-Input'):
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signature_header = headers['Signature-Input']
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else:
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signature_header = headers['signature-input']
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field_sep2 = ','
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# split the signature input into separate fields
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signature_dict = {
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k.strip(): v.strip()
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for k, v in [i.split('=', 1) for i in signature_header.split(';')]
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}
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request_target_key = None
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request_target_str = None
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for key_str, value_str in signature_dict.items():
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if value_str.startswith('('):
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request_target_key = key_str
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request_target_str = value_str[1:-1]
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elif value_str.startswith('"'):
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signature_dict[key_str] = value_str[1:-1]
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if not request_target_key:
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return False
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signature_dict[request_target_key] = request_target_str
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else:
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request_target_key = 'headers'
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signature_header = headers['signature']
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field_sep2 = ' '
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# split the signature input into separate fields
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signature_dict = {
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k: v[1:-1]
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for k, v in [i.split('=', 1) for i in signature_header.split(',')]
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}
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if debug:
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print('signature_dict: ' + str(signature_dict))
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# Unpack the signed headers and set values based on current headers and
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# body (if a digest was included)
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signed_header_list = []
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algorithm = 'rsa-sha256'
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digest_algorithm = 'rsa-sha256'
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for signed_header in signature_dict[request_target_key].split(field_sep2):
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signed_header = signed_header.strip()
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if debug:
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print('DEBUG: verify_post_headers signed_header=' + signed_header)
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if signed_header == '(request-target)':
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# original Mastodon http signature
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append_str = f'(request-target): {method.lower()} {path}'
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signed_header_list.append(append_str)
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elif '@request-target' in signed_header:
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# https://tools.ietf.org/html/
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# draft-ietf-httpbis-message-signatures
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append_str = f'@request-target: {method.lower()} {path}'
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signed_header_list.append(append_str)
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elif '@created' in signed_header:
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if signature_dict.get('created'):
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created_str = str(signature_dict['created'])
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append_str = f'@created: {created_str}'
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signed_header_list.append(append_str)
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elif '@expires' in signed_header:
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if signature_dict.get('expires'):
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expires_str = str(signature_dict['expires'])
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append_str = f'@expires: {expires_str}'
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signed_header_list.append(append_str)
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elif '@method' in signed_header:
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append_str = f'@expires: {method}'
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signed_header_list.append(append_str)
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elif '@scheme' in signed_header:
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signed_header_list.append('@scheme: http')
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elif '@authority' in signed_header:
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authority_str = None
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if signature_dict.get('authority'):
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authority_str = str(signature_dict['authority'])
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elif signature_dict.get('Authority'):
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authority_str = str(signature_dict['Authority'])
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if authority_str:
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append_str = f'@authority: {authority_str}'
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signed_header_list.append(append_str)
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elif signed_header == 'algorithm':
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if headers.get(signed_header):
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algorithm = headers[signed_header]
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if debug:
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print('http signature algorithm: ' + algorithm)
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elif signed_header == 'digest':
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if message_body_digest:
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body_digest = message_body_digest
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else:
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body_digest = \
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message_content_digest(message_body_json_str,
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digest_algorithm)
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signed_header_list.append(f'digest: SHA-256={body_digest}')
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elif signed_header == 'content-length':
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if headers.get(signed_header):
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append_str = f'content-length: {headers[signed_header]}'
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signed_header_list.append(append_str)
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elif headers.get('Content-Length'):
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content_length = headers['Content-Length']
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signed_header_list.append(f'content-length: {content_length}')
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elif headers.get('Content-length'):
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content_length = headers['Content-length']
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append_str = f'content-length: {content_length}'
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signed_header_list.append(append_str)
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else:
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if debug:
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print('DEBUG: verify_post_headers ' + signed_header +
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' not found in ' + str(headers))
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else:
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if headers.get(signed_header):
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if signed_header == 'date' and not no_recency_check:
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if not _verify_recent_signature(headers[signed_header]):
|
|
if debug:
|
|
print('DEBUG: ' +
|
|
'verify_post_headers date is not recent ' +
|
|
headers[signed_header])
|
|
return False
|
|
signed_header_list.append(
|
|
f'{signed_header}: {headers[signed_header]}')
|
|
else:
|
|
if '-' in signed_header:
|
|
# capitalise with dashes
|
|
# my-header becomes My-Header
|
|
header_parts = signed_header.split('-')
|
|
signed_header_cap = None
|
|
for part in header_parts:
|
|
if signed_header_cap:
|
|
signed_header_cap += '-' + part.capitalize()
|
|
else:
|
|
signed_header_cap = part.capitalize()
|
|
else:
|
|
# header becomes Header
|
|
signed_header_cap = signed_header.capitalize()
|
|
|
|
if debug:
|
|
print('signed_header_cap: ' + signed_header_cap)
|
|
|
|
# if this is the date header then check it is recent
|
|
if signed_header_cap == 'Date':
|
|
signed_hdr_cap = headers[signed_header_cap]
|
|
if not _verify_recent_signature(signed_hdr_cap):
|
|
if debug:
|
|
print('DEBUG: ' +
|
|
'verify_post_headers date is not recent ' +
|
|
headers[signed_header])
|
|
return False
|
|
|
|
# add the capitalised header
|
|
if headers.get(signed_header_cap):
|
|
signed_header_list.append(
|
|
f'{signed_header}: {headers[signed_header_cap]}')
|
|
elif '-' in signed_header:
|
|
# my-header becomes My-header
|
|
signed_header_cap = signed_header.capitalize()
|
|
if headers.get(signed_header_cap):
|
|
signed_header_list.append(
|
|
f'{signed_header}: {headers[signed_header_cap]}')
|
|
|
|
# Now we have our header data digest
|
|
signed_header_text = '\n'.join(signed_header_list)
|
|
if debug:
|
|
print('\nverify_post_headers signed_header_text:\n' +
|
|
signed_header_text + '\nEND\n')
|
|
|
|
# Get the signature, verify with public key, return result
|
|
if (headers.get('Signature-Input') and headers.get('Signature')) or \
|
|
(headers.get('signature-input') and headers.get('signature')):
|
|
# https://tools.ietf.org/html/
|
|
# draft-ietf-httpbis-message-signatures
|
|
if headers.get('Signature'):
|
|
headers_sig = headers['Signature']
|
|
else:
|
|
headers_sig = headers['signature']
|
|
# remove sig1=:
|
|
if request_target_key + '=:' in headers_sig:
|
|
headers_sig = headers_sig.split(request_target_key + '=:')[1]
|
|
headers_sig = headers_sig[:len(headers_sig)-1]
|
|
signature = base64.b64decode(headers_sig)
|
|
else:
|
|
# Original Mastodon signature
|
|
headers_sig = signature_dict['signature']
|
|
signature = base64.b64decode(headers_sig)
|
|
if debug:
|
|
print('signature: ' + algorithm + ' ' + headers_sig)
|
|
|
|
# log unusual signing algorithms
|
|
if signature_dict.get('alg'):
|
|
print('http signature algorithm: ' + signature_dict['alg'])
|
|
|
|
# If extra signing algorithms need to be added then do it here
|
|
if not signature_dict.get('alg'):
|
|
alg = hazutils.Prehashed(hashes.SHA256())
|
|
elif (signature_dict['alg'] == 'rsa-sha256' or
|
|
signature_dict['alg'] == 'rsa-v1_5-sha256' or
|
|
signature_dict['alg'] == 'hs2019'):
|
|
alg = hazutils.Prehashed(hashes.SHA256())
|
|
elif (signature_dict['alg'] == 'rsa-sha512' or
|
|
signature_dict['alg'] == 'rsa-pss-sha512'):
|
|
alg = hazutils.Prehashed(hashes.SHA512())
|
|
else:
|
|
alg = hazutils.Prehashed(hashes.SHA256())
|
|
|
|
if digest_algorithm == 'rsa-sha256':
|
|
header_digest = get_sha_256(signed_header_text.encode('ascii'))
|
|
elif digest_algorithm == 'rsa-sha512':
|
|
header_digest = get_sha_512(signed_header_text.encode('ascii'))
|
|
else:
|
|
print('Unknown http digest algorithm: ' + digest_algorithm)
|
|
header_digest = ''
|
|
padding_str = padding.PKCS1v15()
|
|
|
|
try:
|
|
pubkey.verify(signature, header_digest, padding_str, alg)
|
|
return True
|
|
except BaseException:
|
|
if debug:
|
|
print('EX: verify_post_headers pkcs1_15 verify failure')
|
|
return False
|