105 lines
2.9 KiB
Python
105 lines
2.9 KiB
Python
#!/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 dataclasses import dataclass
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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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from werkzeug.datastructures import Headers
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@dataclass
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class SignedData:
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"""
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Signature data
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"""
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method: str
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path: str
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signed_list: list
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body_digest: str | None
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headers: Headers
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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) # pylint: disable=E1102
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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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signed_data: SignedData,
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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_str in signed_data.signed_list:
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if signed_str == "(request-target)":
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signed_string.append("(request-target): "
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+ signed_data.method.lower() + ' ' + signed_data.path)
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elif signed_str == "digest" and signed_data.body_digest:
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signed_string.append("digest: " + signed_data.body_digest)
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else:
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signed_string.append(signed_str + ": "
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+ signed_data.headers[signed_str])
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return "\n".join(signed_string)
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