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local aes = require("aeslua.aes");
local util = require("aeslua.util");
local buffer = require("aeslua.buffer");
local public = {};
aeslua.ciphermode = public;
--
-- Encrypt strings
-- key - byte array with key
-- string - string to encrypt
-- modefunction - function for cipher mode to use
--
function public.encryptString(key, data, modeFunction)
local iv = iv or {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
local keySched = aes.expandEncryptionKey(key);
local encryptedData = buffer.new();
for i = 1, #data/16 do
local offset = (i-1)*16 + 1;
local byteData = {string.byte(data,offset,offset +15)};
modeFunction(keySched, byteData, iv);
buffer.addString(encryptedData, string.char(unpack(byteData)));
end
return buffer.toString(encryptedData);
end
--
-- the following 4 functions can be used as
-- modefunction for encryptString
--
-- Electronic code book mode encrypt function
function public.encryptECB(keySched, byteData, iv)
aes.encrypt(keySched, byteData, 1, byteData, 1);
end
-- Cipher block chaining mode encrypt function
function public.encryptCBC(keySched, byteData, iv)
util.xorIV(byteData, iv);
aes.encrypt(keySched, byteData, 1, byteData, 1);
for j = 1,16 do
iv[j] = byteData[j];
end
end
-- Output feedback mode encrypt function
function public.encryptOFB(keySched, byteData, iv)
aes.encrypt(keySched, iv, 1, iv, 1);
util.xorIV(byteData, iv);
end
-- Cipher feedback mode encrypt function
function public.encryptCFB(keySched, byteData, iv)
aes.encrypt(keySched, iv, 1, iv, 1);
util.xorIV(byteData, iv);
for j = 1,16 do
iv[j] = byteData[j];
end
end
--
-- Decrypt strings
-- key - byte array with key
-- string - string to decrypt
-- modefunction - function for cipher mode to use
--
function public.decryptString(key, data, modeFunction)
local iv = iv or {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
local keySched;
if (modeFunction == public.decryptOFB or modeFunction == public.decryptCFB) then
keySched = aes.expandEncryptionKey(key);
else
keySched = aes.expandDecryptionKey(key);
end
local decryptedData = buffer.new();
for i = 1, #data/16 do
local offset = (i-1)*16 + 1;
local byteData = {string.byte(data,offset,offset +15)};
iv = modeFunction(keySched, byteData, iv);
buffer.addString(decryptedData, string.char(unpack(byteData)));
end
return buffer.toString(decryptedData);
end
--
-- the following 4 functions can be used as
-- modefunction for decryptString
--
-- Electronic code book mode decrypt function
function public.decryptECB(keySched, byteData, iv)
aes.decrypt(keySched, byteData, 1, byteData, 1);
return iv;
end
-- Cipher block chaining mode decrypt function
function public.decryptCBC(keySched, byteData, iv)
local nextIV = {};
for j = 1,16 do
nextIV[j] = byteData[j];
end
aes.decrypt(keySched, byteData, 1, byteData, 1);
util.xorIV(byteData, iv);
return nextIV;
end
-- Output feedback mode decrypt function
function public.decryptOFB(keySched, byteData, iv)
aes.encrypt(keySched, iv, 1, iv, 1);
util.xorIV(byteData, iv);
return iv;
end
-- Cipher feedback mode decrypt function
function public.decryptCFB(keySched, byteData, iv)
local nextIV = {};
for j = 1,16 do
nextIV[j] = byteData[j];
end
aes.encrypt(keySched, iv, 1, iv, 1);
util.xorIV(byteData, iv);
return nextIV;
end
return public; |