mirror of https://gitlab.com/bashrc2/epicyon
472 lines
18 KiB
Python
472 lines
18 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__ = "1.2.0"
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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-01
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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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import datetime
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from utils import getFullDomain
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from utils import getSHA256
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from utils import getSHA512
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from utils import localActorUrl
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def messageContentDigest(messageBodyJsonStr: str) -> str:
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msg = messageBodyJsonStr.encode('utf-8')
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hashResult = getSHA256(msg)
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return base64.b64encode(hashResult).decode('utf-8')
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def signPostHeaders(dateStr: str, privateKeyPem: str,
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nickname: str,
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domain: str, port: int,
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toDomain: str, toPort: int,
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path: str,
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httpPrefix: str,
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messageBodyJsonStr: str,
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contentType: 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 = getFullDomain(domain, port)
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toDomain = getFullDomain(toDomain, toPort)
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if not dateStr:
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dateStr = 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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keyID = localActorUrl(httpPrefix, nickname, domain)
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else:
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# instance actor
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keyID = httpPrefix + '://' + domain + '/actor'
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keyID += '#main-key'
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if not messageBodyJsonStr:
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headers = {
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'(request-target)': f'get {path}',
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'host': toDomain,
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'date': dateStr,
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'accept': contentType
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}
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else:
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bodyDigest = messageContentDigest(messageBodyJsonStr)
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contentLength = len(messageBodyJsonStr)
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headers = {
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'(request-target)': f'post {path}',
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'host': toDomain,
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'date': dateStr,
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'digest': f'SHA-256={bodyDigest}',
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'content-type': 'application/activity+json',
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'content-length': str(contentLength)
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}
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key = load_pem_private_key(privateKeyPem.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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signedHeaderKeys = headers.keys()
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signedHeaderText = ''
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for headerKey in signedHeaderKeys:
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signedHeaderText += f'{headerKey}: {headers[headerKey]}\n'
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# strip the trailing linefeed
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signedHeaderText = signedHeaderText.rstrip('\n')
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# signedHeaderText.encode('ascii') matches
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headerDigest = getSHA256(signedHeaderText.encode('ascii'))
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# print('headerDigest2: ' + str(headerDigest))
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# Sign the digest
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rawSignature = key.sign(headerDigest,
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padding.PKCS1v15(),
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hazutils.Prehashed(hashes.SHA256()))
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signature = base64.b64encode(rawSignature).decode('ascii')
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# Put it into a valid HTTP signature format
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signatureDict = {
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'keyId': keyID,
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'algorithm': 'rsa-sha256',
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'headers': ' '.join(signedHeaderKeys),
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'signature': signature
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}
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signatureHeader = ','.join(
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[f'{k}="{v}"' for k, v in signatureDict.items()])
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return signatureHeader
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def signPostHeadersNew(dateStr: str, privateKeyPem: str,
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nickname: str,
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domain: str, port: int,
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toDomain: str, toPort: int,
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path: str,
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httpPrefix: str,
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messageBodyJsonStr: str,
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algorithm: str) -> (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-01
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"""
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domain = getFullDomain(domain, port)
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toDomain = getFullDomain(toDomain, toPort)
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timeFormat = "%a, %d %b %Y %H:%M:%S %Z"
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if not dateStr:
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currTime = gmtime()
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dateStr = strftime(timeFormat, currTime)
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else:
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currTime = datetime.datetime.strptime(dateStr, timeFormat)
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secondsSinceEpoch = \
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int((currTime - datetime.datetime(1970, 1, 1)).total_seconds())
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keyID = localActorUrl(httpPrefix, nickname, domain) + '#main-key'
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if not messageBodyJsonStr:
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headers = {
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'*request-target': f'post {path}',
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'*created': str(secondsSinceEpoch),
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'host': toDomain,
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'date': dateStr,
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'content-type': 'application/json'
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}
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else:
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bodyDigest = messageContentDigest(messageBodyJsonStr)
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contentLength = len(messageBodyJsonStr)
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headers = {
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'*request-target': f'post {path}',
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'*created': str(secondsSinceEpoch),
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'host': toDomain,
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'date': dateStr,
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'digest': f'SHA-256={bodyDigest}',
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'content-type': 'application/activity+json',
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'content-length': str(contentLength)
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}
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key = load_pem_private_key(privateKeyPem.encode('utf-8'),
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None, backend=default_backend())
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# build a digest for signing
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signedHeaderKeys = headers.keys()
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signedHeaderText = ''
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for headerKey in signedHeaderKeys:
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signedHeaderText += f'{headerKey}: {headers[headerKey]}\n'
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signedHeaderText = signedHeaderText.strip()
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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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headerDigest = getSHA512(signedHeaderText.encode('ascii'))
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rawSignature = key.sign(headerDigest,
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padding.PKCS1v15(),
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hazutils.Prehashed(hashes.SHA512()))
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signature = base64.b64encode(rawSignature).decode('ascii')
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else:
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# default rsa-sha256
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headerDigest = getSHA256(signedHeaderText.encode('ascii'))
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rawSignature = key.sign(headerDigest,
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padding.PKCS1v15(),
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hazutils.Prehashed(hashes.SHA256()))
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signature = base64.b64encode(rawSignature).decode('ascii')
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sigKey = 'sig1'
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# Put it into a valid HTTP signature format
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signatureInputDict = {
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'keyId': keyID,
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}
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signatureIndexHeader = '; '.join(
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[f'{k}="{v}"' for k, v in signatureInputDict.items()])
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signatureIndexHeader += '; alg=hs2019'
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signatureIndexHeader += '; created=' + str(secondsSinceEpoch)
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signatureIndexHeader += \
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'; ' + sigKey + '=(' + ', '.join(signedHeaderKeys) + ')'
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signatureDict = {
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sigKey: signature
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}
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signatureHeader = '; '.join(
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[f'{k}=:{v}:' for k, v in signatureDict.items()])
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return signatureIndexHeader, signatureHeader
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def createSignedHeader(dateStr: str, privateKeyPem: str, nickname: str,
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domain: str, port: int,
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toDomain: str, toPort: int,
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path: str, httpPrefix: str, withDigest: bool,
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messageBodyJsonStr: str,
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contentType: str) -> {}:
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"""Note that the domain is the destination, not the sender
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"""
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headerDomain = getFullDomain(toDomain, toPort)
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# if no date is given then create one
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if not dateStr:
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dateStr = 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 contentType:
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contentType = 'application/activity+json'
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if not withDigest:
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headers = {
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'(request-target)': f'get {path}',
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'host': headerDomain,
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'date': dateStr,
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'accept': contentType
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}
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signatureHeader = \
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signPostHeaders(dateStr, privateKeyPem, nickname,
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domain, port, toDomain, toPort,
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path, httpPrefix, None, contentType)
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else:
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bodyDigest = messageContentDigest(messageBodyJsonStr)
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contentLength = len(messageBodyJsonStr)
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headers = {
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'(request-target)': f'post {path}',
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'host': headerDomain,
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'date': dateStr,
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'digest': f'SHA-256={bodyDigest}',
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'content-length': str(contentLength),
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'content-type': contentType
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}
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signatureHeader = \
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signPostHeaders(dateStr, privateKeyPem, nickname,
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domain, port,
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toDomain, toPort,
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path, httpPrefix, messageBodyJsonStr,
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contentType)
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headers['signature'] = signatureHeader
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return headers
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def _verifyRecentSignature(signedDateStr: 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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currDate = datetime.datetime.utcnow()
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dateFormat = "%a, %d %b %Y %H:%M:%S %Z"
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signedDate = datetime.datetime.strptime(signedDateStr, dateFormat)
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timeDiffSec = (currDate - signedDate).seconds
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# 12 hours tollerance
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if timeDiffSec > 43200:
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print('WARN: Header signed too long ago: ' + signedDateStr)
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print(str(timeDiffSec / (60 * 60)) + ' hours')
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return False
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if timeDiffSec < 0:
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print('WARN: Header signed in the future! ' + signedDateStr)
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print(str(timeDiffSec / (60 * 60)) + ' hours')
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return False
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return True
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def verifyPostHeaders(httpPrefix: str, publicKeyPem: str, headers: dict,
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path: str, GETmethod: bool,
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messageBodyDigest: str,
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messageBodyJsonStr: str, debug: bool,
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noRecencyCheck: 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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publicKeyPem - 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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GETmethod - GET or POST
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messageBodyJsonStr - the received request body (used for digest)
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"""
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if GETmethod:
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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: verifyPostHeaders ' + method)
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print('verifyPostHeaders publicKeyPem: ' + str(publicKeyPem))
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print('verifyPostHeaders headers: ' + str(headers))
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print('verifyPostHeaders messageBodyJsonStr: ' +
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str(messageBodyJsonStr))
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pubkey = load_pem_public_key(publicKeyPem.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'):
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signatureHeader = headers['Signature-Input']
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fieldSep2 = ','
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# split the signature input into separate fields
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signatureDict = {
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k.strip(): v.strip()
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for k, v in [i.split('=', 1) for i in signatureHeader.split(';')]
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}
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requestTargetKey = None
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requestTargetStr = None
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for k, v in signatureDict.items():
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if v.startswith('('):
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requestTargetKey = k
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requestTargetStr = v[1:-1]
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break
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if not requestTargetKey:
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return False
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signatureDict[requestTargetKey] = requestTargetStr
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else:
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requestTargetKey = 'headers'
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signatureHeader = headers['signature']
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fieldSep2 = ' '
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# split the signature input into separate fields
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signatureDict = {
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k: v[1:-1]
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for k, v in [i.split('=', 1) for i in signatureHeader.split(',')]
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}
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if debug:
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print('signatureDict: ' + str(signatureDict))
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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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signedHeaderList = []
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algorithm = 'rsa-sha256'
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for signedHeader in signatureDict[requestTargetKey].split(fieldSep2):
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signedHeader = signedHeader.strip()
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if debug:
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print('DEBUG: verifyPostHeaders signedHeader=' + signedHeader)
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if signedHeader == '(request-target)':
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# original Mastodon http signature
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appendStr = f'(request-target): {method.lower()} {path}'
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signedHeaderList.append(appendStr)
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elif '*request-target' in signedHeader:
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# https://tools.ietf.org/html/
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# draft-ietf-httpbis-message-signatures-01
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appendStr = f'*request-target: {method.lower()} {path}'
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# remove ()
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# if appendStr.startswith('('):
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# appendStr = appendStr.split('(')[1]
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# if ')' in appendStr:
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# appendStr = appendStr.split(')')[0]
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signedHeaderList.append(appendStr)
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elif signedHeader == 'algorithm':
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if headers.get(signedHeader):
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algorithm = headers[signedHeader]
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elif signedHeader == 'digest':
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if messageBodyDigest:
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bodyDigest = messageBodyDigest
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else:
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bodyDigest = messageContentDigest(messageBodyJsonStr)
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signedHeaderList.append(f'digest: SHA-256={bodyDigest}')
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elif signedHeader == 'content-length':
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if headers.get(signedHeader):
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appendStr = f'content-length: {headers[signedHeader]}'
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signedHeaderList.append(appendStr)
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elif headers.get('Content-Length'):
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contentLength = headers['Content-Length']
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signedHeaderList.append(f'content-length: {contentLength}')
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elif headers.get('Content-length'):
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contentLength = headers['Content-length']
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appendStr = f'content-length: {contentLength}'
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signedHeaderList.append(appendStr)
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else:
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if debug:
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print('DEBUG: verifyPostHeaders ' + signedHeader +
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' not found in ' + str(headers))
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else:
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if headers.get(signedHeader):
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if signedHeader == 'date' and not noRecencyCheck:
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if not _verifyRecentSignature(headers[signedHeader]):
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if debug:
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print('DEBUG: ' +
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'verifyPostHeaders date is not recent ' +
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headers[signedHeader])
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return False
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signedHeaderList.append(
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f'{signedHeader}: {headers[signedHeader]}')
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else:
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if '-' in signedHeader:
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# capitalise with dashes
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# my-header becomes My-Header
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headerParts = signedHeader.split('-')
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signedHeaderCap = None
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for part in headerParts:
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if signedHeaderCap:
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signedHeaderCap += '-' + part.capitalize()
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else:
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signedHeaderCap = part.capitalize()
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else:
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# header becomes Header
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signedHeaderCap = signedHeader.capitalize()
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if debug:
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print('signedHeaderCap: ' + signedHeaderCap)
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# if this is the date header then check it is recent
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if signedHeaderCap == 'Date':
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if not _verifyRecentSignature(headers[signedHeaderCap]):
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if debug:
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print('DEBUG: ' +
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'verifyPostHeaders date is not recent ' +
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headers[signedHeader])
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return False
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# add the capitalised header
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if headers.get(signedHeaderCap):
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signedHeaderList.append(
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f'{signedHeader}: {headers[signedHeaderCap]}')
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elif '-' in signedHeader:
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# my-header becomes My-header
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signedHeaderCap = signedHeader.capitalize()
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if headers.get(signedHeaderCap):
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signedHeaderList.append(
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f'{signedHeader}: {headers[signedHeaderCap]}')
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# Now we have our header data digest
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signedHeaderText = '\n'.join(signedHeaderList)
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if debug:
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print('signedHeaderText:\n' + signedHeaderText + 'END')
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# Get the signature, verify with public key, return result
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signature = None
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if headers.get('Signature-Input') and headers.get('Signature'):
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# https://tools.ietf.org/html/
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# draft-ietf-httpbis-message-signatures-01
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headersSig = headers['Signature']
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# remove sig1=:
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if requestTargetKey + '=:' in headersSig:
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headersSig = headersSig.split(requestTargetKey + '=:')[1]
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headersSig = headersSig[:len(headersSig)-1]
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signature = base64.b64decode(headersSig)
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else:
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# Original Mastodon signature
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signature = base64.b64decode(signatureDict['signature'])
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if debug:
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print('signature: ' + algorithm + ' ' +
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signatureDict['signature'])
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# If extra signing algorithms need to be added then do it here
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if algorithm == 'rsa-sha256':
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headerDigest = getSHA256(signedHeaderText.encode('ascii'))
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paddingStr = padding.PKCS1v15()
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alg = hazutils.Prehashed(hashes.SHA256())
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elif algorithm == 'rsa-sha512':
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headerDigest = getSHA512(signedHeaderText.encode('ascii'))
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paddingStr = padding.PKCS1v15()
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alg = hazutils.Prehashed(hashes.SHA512())
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else:
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print('Unknown http signature algorithm: ' + algorithm)
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paddingStr = padding.PKCS1v15()
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alg = hazutils.Prehashed(hashes.SHA256())
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headerDigest = ''
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try:
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pubkey.verify(signature, headerDigest, paddingStr, alg)
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return True
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except BaseException:
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if debug:
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print('EX: verifyPostHeaders pkcs1_15 verify failure')
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return False
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