bitbot-3.11-fork/modules/fediverse/ap_security.py

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import base64, typing
try:
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from cryptography import x509
from cryptography.hazmat.primitives import hashes, serialization
from cryptography.hazmat.primitives.asymmetric import padding, rsa
from cryptography.hazmat.backends import default_backend
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from cryptography.hazmat.primitives.serialization import Encoding
from cryptography.hazmat.primitives.serialization import PublicFormat
has_crypto = True
except ModuleNotFoundError:
has_crypto = False
SIGNATURE_FORMAT = (
"keyId=\"%s\",headers=\"%s\",signature=\"%s\",algorithm=\"rsa-sha256\"")
def _private_key(key_filename: str) -> rsa.RSAPrivateKey:
with open(key_filename, "rb") as key_file:
return serialization.load_pem_private_key(
key_file.read(), password=None, backend=default_backend())
class PrivateKey(object):
def __init__(self, filename, id):
self.key = _private_key(filename)
self.id = id
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def public_key(key_filename: str) -> str:
with open(key_filename, "rb") as key_file:
cert = x509.load_pem_x509_certificate(key_file.read(),
default_backend())
return cert.public_key().public_bytes(
Encoding.PEM, PublicFormat.SubjectPublicKeyInfo).decode("ascii")
def signature(key: PrivateKey, headers: typing.List[typing.Tuple[str, str]]
) -> str:
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sign_header_keys = " ".join(h[0].lower() for h in headers)
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sign_string_parts = ["%s: %s" % (k.lower(), v) for k, v in headers]
sign_string = "\n".join(sign_string_parts)
signature = key.key.sign(
sign_string.encode("utf8"),
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padding.PKCS1v15(),
hashes.SHA256()
)
signature = base64.b64encode(signature).decode("ascii")
return SIGNATURE_FORMAT % (key.id, sign_header_keys, signature)