Signature Verification

Signature Verification

Python

from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.asymmetric import padding
from cryptography.hazmat.primitives.serialization import load_pem_public_key
 
def verify_signature(public_key_path, message, signature):
    with open(public_key_path, 'rb') as key_file:
        public_key = load_pem_public_key(key_file.read())
 
    try:
        public_key.verify(
            signature,
            message,
            padding.PSS(
                mgf=padding.MGF1(hashes.SHA256()),
                salt_length=padding.PSS.MAX_LENGTH
            ),
            hashes.SHA256()
        )
        print("Signature is valid.")
        return True
    except Exception:
        print("Signature is invalid.")
        return False
 
# Usage example
public_key_path = 'public_key.pem'
message = b'This is the message that was signed.'
signature = b'\x00\x11\x22...'  # Replace with the actual signature
 
verify_signature(public_key_path, message, signature)

Here's how you can use the code:

1. Replace 'public_key.pem' with the path to your public key file. Make sure the key is in PEM format.
2. Replace message with the message that was signed.
3. Replace signature with the actual signature you want to verify.

When you run the code, it will load the public key from the specified file, verify the signature against the message, and print whether the signature is valid or invalid.

Make sure you have the cryptography library installed before running the code. You can install it using pip:

pip install cryptography

Note that this code assumes you have a public key and a signature in hand. If you need to generate keys and sign messages as well, let me know, and I can provide additional code for that.