96 lines
2.7 KiB
Python
96 lines
2.7 KiB
Python
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#!/usr/bin/env python3
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"""
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Verify and build HTTP signatures
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"""
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import base64
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from Crypto.Hash import SHA256
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from Crypto.Signature import PKCS1_v1_5
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from Crypto.PublicKey import RSA
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class HttpSignature:
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"""
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calculation and verification of HTTP signatures
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"""
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@classmethod
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def calculation_digest(
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cls,
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body : bytes,
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algorithm : str ="sha-256"
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) -> str:
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"""
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Calculates the digest header value for a given HTTP body
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"""
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if "sha-256" == algorithm:
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body_digest = SHA256.new()
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body_digest.update(body)
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return "SHA-256=" + \
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base64.b64encode(body_digest.digest()
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).decode("utf-8")
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raise ValueError(f"No support algorithm {algorithm}")
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@classmethod
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def verify_signature(
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cls,
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signature_string : str,
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signature : bytes,
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pubkey,
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) -> bool:
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"""
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Verify signatur that returns bool
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"""
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pubkey = RSA.importKey(pubkey)
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signer = PKCS1_v1_5.new(pubkey)
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digest = SHA256.new()
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digest.update(signature_string.encode("utf-8"))
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return signer.verify(digest, signature)
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@classmethod
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def parse_signature(
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cls,
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signature : str
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) -> dict:
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"""
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Parse signature string in headers
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"""
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detail = {}
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for item in signature.split(','):
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name, value = item.split('=', 1)
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value = value.strip('"')
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detail[name.lower()] = value
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signature_details = {
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"headers": detail["headers"].split(),
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"signature": base64.b64decode(detail["signature"]),
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"algorithm": detail["algorithm"],
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"keyid": detail["keyid"],
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}
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return signature_details
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@classmethod
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def build_signature_string(
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cls,
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method : str,
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path : str,
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signed_headers : list,
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body_digest : str | None,
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headers,
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) -> str:
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"""
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Build signature string
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"""
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signed_string = []
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for signed_header in signed_headers:
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if signed_header == "(request-target)":
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signed_string.append("(request-target): "
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+ method.lower() + ' ' + path)
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elif signed_header == "digest" and body_digest:
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signed_string.append("digest: " + body_digest)
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else:
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signed_string.append(signed_header + ": "
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+ headers[signed_header])
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return "\n".join(signed_string)
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