I am trying to sign a piece of text using a private key using SwiftyRSA, which I do successfully. Then send the signature to the python server which holds the public key for verification. the But I keep receiving the InvalidSignature exception.
I have tried different hashing algorithms, bit sizes, but still the same InvalidSignature exception. I am sure that the key and signature are related b/c they are generated at the same time!
My issue is not with the libraries themselves--which I think are functioning properly. I think it has to do with a padding discrepancy between the two libraries. Cryptography is using PSS, while I cant find the padding/salt that SwiftyRSA uses.
Key Verification Script
@app.route('/', methods=['POST'])
def verify():
record = json.loads(request.data)
signature = record['sig']
public_key = record['public_key']
hash_local_token = record['hash_local_token']
input_string = record['input_string']
verification_response = auth.verify_signature(signature=signature, pub_key=public_key, input_string=input_string)
print(verification_response)
return jsonify({"Verification": verification_response})
def verify_signature(signature, pub_key, input_string):
# Load the public key
# Url Safe Base64 Decoding
derdata = base64.b64decode(pub_key)
public_key = load_der_public_key(derdata, default_backend())
signature_decoded = base64.urlsafe_b64decode(signature)
# Perform the verification.
try:
public_key.verify(
signature_decoded,
str.encode(input_string),
padding.PSS(
mgf=padding.MGF1(hashes.SHA256()),
salt_length=padding.PSS.MAX_LENGTH,
),
hashes.SHA256(),
)
return "SUCCESS: Signature Verified!"
except cryptography.exceptions.InvalidSignature as e:
return 'FAILED: Payload and/or signature files failed verification'
Key Generation Script
func moreTesting() {
do {
let keyPair = try SwiftyRSA.generateRSAKeyPair(sizeInBits: 4096)
let privateKey = keyPair.privateKey
let publicKey = keyPair.publicKey
let inputString = "test_string"
let clear = try ClearMessage(string: inputString, using: .utf8)
let signature = try clear.signed(with: privateKey, digestType: .sha256)
let base64Signature = signature.base64String
let parameters: [String: String] = [
"sig": base64Signature,
"input_string": inputString,
"public_key": try publicKey.base64String()
]
AF.request("http://127.0.0.1:5000/", method: .post, parameters: parameters, encoder: JSONParameterEncoder.default).responseJSON { response in
debugPrint(response)
}
}
catch {
print(Error.self)
}
}
