Digital Signature Generation & Verfication in RSA Algorithm

In RSA, we know that there are 2 keys, namely public and private key, public key being available to everyone. There can be cases where the receiver actually receives more than one encrypted message. Now, the task is, how will the receiver know that the sender is legit or not ?

In order to solve this problem, the concept of Digital signature is introduced into RSA Algorithm. In thiscenario, if person A wants to send a message to person B, then person A first produces a hash vale for the message, raises it to the power of d mod n and attaches it as a signature to the message. When person B receives the messsage, B raises the signed message to the power of e mod n and compares the resulting hash value with the message's actual hash value. If the two agree, then person B can be sure that the message has not been tampered with. zin the following examples, we will be signing the message itself instead of its hash value.

Generation:

The above picture displays the code for encrytion of signature.The following picture represents the output of the above code.

Verification:

The below picture gives the code for signature verfication :

The following picture displays the hexadecimal value of the signature first. In order to change it into an alphabetic string, the following python code is used :

$ python -c 'print("4C61756E63682061206D697373696C652E".decode("hex"))'