foxhole/app/httpsig.py

77 lines
2.3 KiB
Python

#!/usr/bin/env python3
import base64
from typing import Literal, TypedDict, cast, Any
from typing import Optional
from Crypto.Hash import SHA256
from Crypto.Signature import PKCS1_v1_5
from Crypto.PublicKey import RSA
class HttpSignature:
"""
calculation and verification of HTTP signatures
"""
@classmethod
def calculation_digest(
cls,
body : bytes,
algorithm : str ="sha-256"
)-> str :
"""
Calculates the digest header value for a given HTTP body
"""
if "sha-256" == algorithm:
h = SHA256.new()
h.update(body)
return "SHA-256=" + \
base64.b64encode(h.digest()).decode("utf-8")
else:
raise ValueError(f"No support algorithm {algorithm}")
@classmethod
def verify_signature(
cls,
signature_string : str,
signature : bytes,
pubkey,
) -> bool :
pubkey = RSA.importKey(pubkey)
signer = PKCS1_v1_5.new(pubkey)
digest = SHA256.new()
digest.update(signature_string.encode("utf-8"))
return signer.verify(digest, signature)
@classmethod
def parse_signature(cls, signature):
_detail = {}
for item in signature.split(","):
name, value = item.split("=", 1)
value = value.strip('"')
_detail[name.lower()] = value
signature_details = {
"headers": _detail["headers"].split(),
"signature": base64.b64decode(_detail["signature"]),
"algorithm": _detail["algorithm"],
"keyid": _detail["keyid"],
}
return signature_details
@classmethod
def build_signature_string(
cls,
method : str,
path : str,
signed_headers : dict,
body_digest : str,
headers,
) -> str :
signed_string = []
for signed_header in signed_headers:
if signed_header == "(request-target)":
signed_string.append("(request-target): " + method.lower() + " " + path)
elif signed_header == "digest" and body_digest:
signed_string.append("digest: " + body_digest)
else:
signed_string.append(signed_header + ": " + headers[signed_header])
return "\n".join(signed_string)