Created
December 11, 2012 13:01
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# CFB ENCRYPT | |
# 1. przygotować IV do ECB | |
# 2. zaszyfrować IV w trybie ECB | |
# 3. zabrać z wyjścia (2) z ECB [feedbackSize] bajtów z początku | |
# 4. StringXor [feedbackSize] bajtów wejścia z [feedbackSize] bajtami wyjścia ECB | |
# 5. Efekt (4) dodać do szyfrogramu | |
# 6. Efekt (4) wstawić na koniec IV do ECB z (1) | |
# 7. Usunąć [feedbackSize] bajtów z -początku- IV do ECB z (1) | |
require 'openssl' | |
input = 'abcdefghijklmnopqrstuwvxyz' | |
puts 'RUBY :: CFB from ECB' | |
puts ' IN: ' + input.bytesize.to_s + ' :: ' + input | |
for feedbackSize in 1..8 | |
c = OpenSSL::Cipher.new('bf-ecb') | |
c.encrypt | |
c.key = '1234567890123456' | |
block = '00000000' | |
enc = c.update(block); | |
out = '' | |
pos = 0 | |
# LOOP | |
while block = input.byteslice(pos, feedbackSize) | |
pos += feedbackSize | |
feedback = enc.byteslice(0, feedbackSize) # 3 | |
enc = enc.byteslice(feedbackSize..8) # 7 | |
sub = (block ^ feedback) # 4 | |
out += sub # 5 | |
block = enc + sub # 6 | |
enc = c.update(block); # 2!! | |
end | |
# ENDLOOP | |
puts ' CFB OUT: ' + out.bytesize.to_s + ' :: ' + out.unpack('h*')[0] + ' :: feedbackSize: ' + feedbackSize.to_s | |
end |
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