A digital signature is:
Digital signature schemes are used for:
An analogy for digital signatures is the sealing of an envelope with a personal wax seal. The message can be opened by anyone, but the presence of the unique seal authenticates the sender.
In a asymmetric scheme (public key cryptography scheme), there is two keys:
An advantage of signing messages is that the public key and certificate are automatically send.
See also Public Key - Digital Signature
In a symmetric scheme, the same key is used to:
Example: JsonWebToken
A signing algorithm given a message and a secret (private or shared key), produces a signature.
To sign a message, the sender
You can see an example of signature procedure with the issuing of certificate
There are usually 2 ways to sign:
Signing method | Message Human Readable | Encryption difficulty |
---|---|---|
encapsulating the text message inside the signature (with delimiters) | Yes | Difficult |
encoding the message altogether with the signature | no (message has been tampered with) | Simple (decryption with the embedded public key) |
A signature verifying algorithm given a message, will either:
the message's claim to authenticity:
The verification:
The recipient will: