Computer Security Service

Before we begin this blog I wanted to understand how public and private key works. We will just do a quick remainder here. A public & private key pair is created at the same time not like one created yesterday and one tomorrowJ. They are created as a mathematical key pair together and the magic is anything you encrypt with one of them can be decrypted with the other and vice versa.  Anything you encrypt with the private key can be decrypted with the public key. Anybody can create the key pair, we can create them either in the cisco router, on a server,. Computer Security Service The secret of them is we can keep the private key private not sharing with anybody and you can share the public key with anybody you want to.

Digital Signature and  how it works

A Digital signature is a hash that has been encrypted with the sender’s private key.

The sender of a packet will take the data and they will create a hash and then will take the hash and encrypt with the private key. Now the sender will send the data and the digital signature (HASH encrypted with private key) to the recipient.

Digital Signature = HASH(DATA)

Sender  (DATA + Digital signature ) --> recipient

Now the recipient takes the data and they generate the own hash and they then take the digital signature which is encrypted hash and they decrypt with the senders public key .  If the result is the same this confirms the integrity between the sender and the recipient.

• Recipient receives the data and digital signature
• Hash the received data
• Decrypts the encrypted hash with senders public key
• Compare both the HASH value.
• If it matches then it compares the data is not tampered or not modified