What is a 'length extension attack' and which hash function family is vulnerable to it?
-
A
An attack on RSA using extended Euclidean algorithm; affects all hash functions
-
B
An attack where knowing H(m) lets an attacker compute H(m||extra) without knowing m; affects SHA-1 and SHA-2 (Merkle-Damgård)
-
C
An attack on Merkle trees using extra leaf nodes; affects SHA-3 only
-
D
An attack that extends private keys; affects ECDSA