Benefits of the Digital Signature and How to use Digital Sign
Are you looking for using Digital Signature?, To know more about the new technique of digital signature used in paperless office. when someone issue order or instruction through emails, there is no way to use the normal signature to keep as proof of having issues some instruction, so digital signature is required to prevent repudiation of orders made through emails.
How Digital Sign Technique Work?
First of all take the Hash Value of the Document using the Hash function. The hash function produces a fixed-length string or number independent of the document size.
The Hash value(x)is then transformed using the private key of the owner of the document to produce the signature block of the document.That is, signature=Private-key-transform(x).
This signature is appended to the document and sends to the receiver.the receiver on receiving the document and signature, first applies the hash function on the document and gets the hash value, say Y, of receiver document.
The receiver then uses the sender’s public key to transform the signature received back to the original hash value. That is, x=public key transform the signature(signature).
If the two computed hash values are the same(x equals y), the document received is the same as the one send by the sender. Otherwise, the document is tampered or changed on the way.
For the above Technique to work the Transformation done by the public key must be exact inverse of the transformation done by the private key.