Digital Signature

A digital signature is an electronic, encrypted, stamp of authentication on digital information such as email messages or electronic documents.
A signature confirms that the information originated from the signer and has not been altered.
It provides the highest levels of security and universal acceptance.

When the sender electronically signs a document two keys are generated: Public and Private.
The private key is kept by the signer and it should be kept securely. On the other hand, the receiver must have the public key to decrypt the message.
Then the Hash function is used on the document to create Hash, which is also known as digest.
Then the private key is used to encrypt hash.
The document is sent to the recipients along with the sender's public key.

The recipient receives the document and decrypts the encrypted hash with the sender's public key certificate.
A cryptographic hash is again generated on the recipient's end using the same hash function that the sender used.
Both cryptographic hashes(of sender and receiver) are compared to check its authenticity.
If they match, the document hasn't been tampered with and is considered valid.

Computer Engineering