(Nov-20-2018, 05:01 PM)gontajones Wrote: Which steps did you follow?

1 - Create a key-pair with ssh-keygen
2 - Generate a signature for some "data.txt" with openssl dgst -sign ~/.ssh/id_rsa data.txt > signature
3 - Encode signature and "data.txt" with base64.b64encode().
4 - Call verify_sign("~/.ssh/id_rsa.pub", signature_b64, data_b64)

def verify_sign(public_key_loc, signature, data):
    '''
    Verifies with a public key from whom the data came that it was indeed 
    signed by their private key
    param: public_key_loc Path to public key
    param: signature String signature to be verified
    return: Boolean. True if the signature is valid; False otherwise. 
    '''
    from Crypto.PublicKey import RSA 
    from Crypto.Signature import PKCS1_v1_5 
    from Crypto.Hash import SHA512
    from base64 import b64decode 
    pub_key = open(public_key_loc, "r").read() 
    rsakey = RSA.importKey(pub_key) 
    signer = PKCS1_v1_5.new(rsakey) 
    digest = SHA512.new() 
    # Assumes the data is base64 encoded to begin with
    digest.update(b64decode(data)) 
    if signer.verify(digest, b64decode(signature)):
        return True
    return False

(Nov-20-2018, 05:12 PM)gontajones Wrote: Yep, I run this code in my step 4 and it returned True.

(Nov-20-2018, 05:26 PM)saisankalpj Wrote:

(Nov-20-2018, 05:12 PM)gontajones Wrote: Yep, I run this code in my step 4 and it returned True.

Yeah but the problem for me is in line 17 i am hard coding the key as “BEGIN PUBLIC KEY ”+ hardcoded key value+”END PUBLIC KEY”. But i am getting false

Output:
ssh-rsa AAAAB3N...ns3bhHGhjR6XCJcFik9K/ne+uhSy40Ij user@linux

(Nov-20-2018, 05:41 PM)gontajones Wrote:

(Nov-20-2018, 05:26 PM)saisankalpj Wrote: Yeah but the problem for me is in line 17 i am hard coding the key as “BEGIN PUBLIC KEY ”+ hardcoded key value+”END PUBLIC KEY”. But i am getting false

The key that you are mentioning is a private key, the function needs the public key (and it reads it from file).
Your public key file should looks like:

Output:
ssh-rsa AAAAB3N...ns3bhHGhjR6XCJcFik9K/ne+uhSy40Ij user@linux

Another question, how are you generating the signature?

(Nov-20-2018, 06:03 PM)gontajones Wrote: Hummm...my bad about saying that you were mentioning a private key, sorry.

This is a RSA public key? It should be.
Try with:
-----BEGIN RSA PUBLIC KEY----- ... -----END RSA PUBLIC KEY-----