what is a digital signature?

Answer 1

"Digital Signature" refers to a method in computer security for authenticating... making sure that the encrypted data is coming from the right person and not somebody pretending to be them.

It is usually used in Public/Private Key encryption. I will try to give a good simple explanation.


When encrypting a message, you convert it to numberic values and apply a mathematical algorithm on it (there are several different ones that work in different ways) involving another number, the KEY. This KEY can be used later to decrypt the message using the same mathematical algorithm. (But the message is unreadable to anybody without the KEY.)

At MIT in 1977 they came up with the RSA algorithm (named after Ron Rivest, Adi Shamir and Len Adleman), one that allowed a different KEY to be used in decrypting the message. So, you can give out a Public Key freely to everybody, that can be used with the RSA algorithm to encrypt a message to you. Now, the only way to decrypt that message is with the corresponding Private Key that ONLY you know.

What's neat, this also works the other way. Because the encrypted and decrypted messages are both just a sequence of numbers/characters....you can used the decrypting method to "encrypt" a readable message with your Private Key. Now, everybody with your Public Key can "decrypt" the message knowing that ONLY YOU could have encrypted it. This is the way to verify that a message came from the right person...a "Digital Signature".

So, using the Public/Private Keys of both people in both dirrections, you can encrypt a message in a way that YOU KNOW only the right person can read it, and THEY KNOW only you could have sent it.

This is how secure internet comunications work.


I hope this explanation was helpful.

Answer 2

i'm not sure for most places, but for the FAFSA (federal financial aid website), the digital signature is a series of numbers or letters they assign you that you give instead of an actual signature. this way, you can submit a web application online instead of having to wait 2-3 days for snail mail.

Answer 3

it's verification that you give online that proves you are who you say you are.