a. Consider the Davies and Price ha

a. Consider the Davies and Price hash code scheme described in Section 11.4 and assume that DES is used as the encryption algorithm:
Hi = Hi-1 + E(Mi, Hi-1)
Recall the complementarity property of DES (Problem 3.14): If Y = E(K, X) ,Then Y’ = E(K’, X’) . Use this property to show how a message consisting of blocks can be altered without altering its hash code
b. Show that a similar attack will succeed against the scheme proposed in [MEYE88]:
Hi = Mi + E(Hi-1, Mi)

Kết quả (Klingon) 1:

wej davies 'ay' 'ej hash ngoq scheme qaStaHvIS 'ay' 11.4 Del qel 'ej 'e' lo' des je encryption algorithm assume.qavan qavan-1 e + = (mi, bIpIv'a'-1)complementarity bang des (qay' 3.14) recall: y vaj e (k, x), ghIq y = = e (k, x). bang DanoHmeH chay' laH choH QIn consisting bot Hutlh ngoq hash choH cha'b. 'e', against scheme qaStaHvIS [meye88] ghoQIjneS Qap HIv nagh cha':qavan mi e (qavan-1, mi) + =