prev
next
Slide 9 of 13
Digital Signatures
- assume that E(D(P)) = P (RSA has this property)
- Alice sends Bob EB(DA(P))
- Bob decrypts with his private key, encrypts with Alice's public key
- to provide authentication without secrecy:
- a digest D of a message P is easily computed given P
- it is very hard to construct a P that has a given digest D
- only encrypt (sign) the digest
- MD5