# Could anyone help me with this math problem please?

*From*: Tonny <tonnyspain@xxxxxxxxx>*Date*: Thu, 17 Jan 2008 19:12:02 -0800 (PST)

Hi all, I am doing a decryption and have some math problems. Hope you

guys could help me out, thanks in advance!

=====================

Let k be a 128-bit binary number.

k1 is the leftmost 64 bits of k, and k2 is the rightmost 64 bits of k.

k3 is the left cyclic shift of k1 (e.g. if k1=001011, then k3= 010110)

k4 is the right cyclic shift of k2 (e.g, if k2=001011, then k4=100101)

Therefore, k1,k2,k3 and k4 are all 64 bits.

Suppose m0,m1,m2,m3,m4,m5 are also 64-bit, and we have

m2= m0 xor m1 xor k1

m3=m1 xor m2 xor k2

m4=m2 xor m3 xor k3

m5=m3 xor m4 xor k4

m0, m1, m4, m5 are known, how can I figure out what k is?

=====================

Any help would be greatly appreciated!

.

**Follow-Ups**:

- Prev by Date:
**Re: Hamiltonian cycle problem in 2-connected bipartite cubic graph is Polynomial** - Next by Date:
**Re: Questions about Parity SAT** - Previous by thread:
**Questions about Parity SAT** - Next by thread:
**Re: Could anyone help me with this math problem please?** - Index(es):