from pylfsr import LFSR
# The initial state
state = [0,0,0,1,0,1,0,1,0,1,1]
# The LFSR polynomial use a primitive polynomail to get maximum period length
poly = [5, 4, 3, 2]
l = LFSR(fpoly=poly, initstate =state)
message = b"This is a Test Message"
ciphertext = b""
# generate all LFSR sequence
allseq = l.runFullCycle()
seq = ""
seq_index = 0
# Convert LFSR bits into a string
for x in allseq:
seq += str(x)
for counter in range(len(message)):
ran_seq = seq[seq_index: seq_index+8]
# Now encrypt by XOR convert to bytes and append to ciphertext
ciphertext += bytes([int(message[counter]) ^ int(ran_seq, 2)])
seq_index += 8 # Move sequence to Next byte
print(ciphertext)
plaintext = b""
# Reset The LFSR sequence to start from beginning
seq_index = 0
for counter in range(len(ciphertext)):
ran_seq = seq[seq_index: seq_index+8]
plaintext += bytes([int(ciphertext[counter]) ^ int(ran_seq, 2)])
seq_index += 8
print(plaintext)
该代码使用
LFSR
移位寄存器获得伪随机序列,然后将其与明文异或以获得密文。代码使用pylfsr
和numpy
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