diff --git a/cw/cw.tex b/cw/cw.tex index d3042f4..05bfc69 100644 --- a/cw/cw.tex +++ b/cw/cw.tex @@ -53,8 +53,8 @@ if the message is only one block long: $$H=E$$ $$m\ne m'$$ - $$H(m)=E(K, IV \xor m) = C_1$$ - $$H(m')=E(K, IV \xor m') = C_2$$ + $$H(m)=E(K, IV \oplus m) = C_1$$ + $$H(m')=E(K, IV \oplus m') = C_2$$ And if there the hashing function was not collision resistant that would imply $$C_1=C_2\implies D(C_1)=D(C_2) \impies m=m'$$ and since $m !=m'$ the hash function is collision resistant, for messages with 1 block.