If we encrypt a plain text using Double DES but with same key K1, Can we get the same result as if we would encrypt the plain text using single DES but with different key, say K2. What I'm asking is can we achieve this for same size of K1 and K2 : DES(K1,DES(K1,m)) = DES(K2,m) What would be effe...

It's common to use a salt before hashing a password in order to prevent an attack by rainbow tables. Would it also work to encrypt the password for instance by RSA encryption - by a permanent RSA private key stored on the server - before hashing? In other words: $hash = SHA(RSA(password))$ For me...

In proof of CPA-security of encryption scheme $(r, F_k(r)\oplus m )$ where: $F_k$ is a keyed function $r\in_R\{0,1\}^n$ is a random number, on page 85 of Introduction to modern cryptography we have The value $r^*$ is used when answering at least one of A’s encryption oracle queries: In this ca...