def ctr_decrypt(cipher, key, nunce):
ctr = 0
blocks = split_to_blocks(cipher)
result = ""
for block in blocks:
bin_nunce = plaintobin(nunce)
bin_ctr = '{0:064b}'.format(ctr)
new_nunce = binary_string(xor(bin_nunce, bin_ctr, 64))
enc_ctr = des_encrypt(new_nunce, key)
bin_enc = plaintobin(enc_ctr)
bin_block = plaintobin(block)
xored = binary_string(xor(bin_enc, bin_block, 64))
ctr += 1
result += xored
return result
def ofb_decrypt(cipher, key, iv):
blocks = split_to_blocks(cipher)
result = ""
for block in blocks:
iv = des_encrypt(iv, key)
bin_iv = plaintobin(iv)
bin_block = plaintobin(block)
xored = binary_string(xor(bin_block, bin_iv, 64))
result += xored
return result
def cbc_encrypt(plain, key, iv):
blocks = split_to_blocks(plain)
result = ""
for block in blocks:
bin_block = plaintobin(block)
bin_iv = plaintobin(iv)
xored = binary_string(xor(bin_block, bin_iv, 64))
iv = des_encrypt(xored, key)
result += iv
return result
def cfb_encrypt(plain, key, iv):
blocks = split_to_blocks(plain)
result = ""
for block in blocks:
enc_iv = des_encrypt(iv, key)
bin_iv = plaintobin(enc_iv)
bin_block = plaintobin(block)
xored = binary_string(xor(bin_block, bin_iv, 64))
iv = xored
result += xored
return result
def cbc_decrypt(cipher, key, iv):
blocks = split_to_blocks(cipher)
result = ""
for block in blocks:
bin_iv = plaintobin(iv)
code = des_decrypt(block, key)
bin_code = plaintobin(code)
xored = binary_string(xor(bin_code, bin_iv, 64))
iv = block
result += xored
return result
