The Berlekamp–Massey algorithm is an algorithm that will find the shortest linear feedback shift register for a given binary output sequence. The algorithm will also find the minimal polynomial of a linearly recurrent sequence in an arbitrary field. I have used sage for computing this program.
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# Berlekamp-Massey Algorithm | |
#from __future__ import print_function | |
s = [GF(2)(0), 0, 1, 0, 0, 0, 0, 0, 1, 1, 0] #input sequence | |
n = len(s) | |
C = [GF(2)(1)] | |
B = [GF(2)(1)] | |
temp = [] | |
T = [] | |
L = 0 | |
N = 0 | |
m = -1 | |
print '----- n',n | |
print '-----------------------------------------------------------------------' | |
while N < n: | |
temp = B | |
d = s[N] | |
for i in range(1,L+1): | |
d = d + C[i]*s[N-i] | |
print '----- d ',d | |
if d == 1: | |
T = C | |
temp = [ 0 for i in range(int(N-m))] + temp | |
if len(C) < len(temp): | |
C = C + [0 for i in range(len(temp)-len(C))] | |
else: | |
temp = temp + [0 for i in range(len(C)-len(temp))] | |
for i in range(len(C)): | |
C[i] = C[i] + temp[i] | |
print '----- temp',temp | |
print '----- C',C | |
if L <= N/2: | |
L = int(N + 1 - L) | |
m = int(N) | |
B = T | |
N = N + 1 | |
print '-----------------------------------------------------------------------' | |
print '----- N',N | |
print '----- L',L | |
j = 0 | |
print '-----------------------------------------------------------------------' | |
print 'Solution is ', #Output registers | |
for i in C: | |
if j < len(C)-1: | |
if i == 1: | |
print i,'x^(',j,')+', | |
else: | |
if i == 1: | |
print i,'x^(',j,')' | |
j+=1 |
https://cocalc.com/share/public_paths/1d32f52ed8182f7f744a166db4a92b06e932ba2a
ReplyDeletehttps://slideplayer.com/slide/13475838/
https://www.sagemath.org/files/kohel-book-2008.pdf&clen=626260&chunk=true
www.sagemath.org/files/thesis/nguyen-thesis-2009.pdf&clen=972814&chunk=true
https://wiki.sagemath.org/interact/cryptography#RSA
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