Could anyone help me with this math problem please?



Hi all, I am doing a decryption and have some math problems. Hope you
guys could help me out, thanks in advance!

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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?

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Any help would be greatly appreciated!
.