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-- ENCRYPT, RNDHASH
if not crypto then crypto = {} end
local rndm = 2^31 − 1; --C++11's minstd_rand
local rnda = 48271; -- generator
local rndseed = 1;
local random = function(n)
rndseed = (rnda*rndseed)% rndm;
return rndseed % n
end
local string2arr = function(input) -- convert string to array of numbers
local m = 32; -- ascii 32-128
local out = {}
for i=1, string.len(input) do
out[i] = string.byte(input,i)-m
if out[i] == -6 then out[i] = 96 end -- conversion back
end
return out
end
local arr2string = function(out) -- convert array back to string
local m = 32
local ret = {}
for i = 1, #out do
if out[i] == 96 then out[i]=-6 end -- 32 + 96 = 128 (bad char)
ret[#ret+1] = string.char(m+out[i])
end
return table.concat(ret,"")
end
--TODO: possible improvements: use 256 bytes in out and instead of "i%3 mod 97" use permutation table
-- like s-box in aes
local pbox = {}; for i = 0, 96 do pbox[i] = i^3 % 97 end -- each value is assigned another (arbitrary) value.faster to just lookup than compute
-- note: f:x->x^3 is homomorphism of Z_97* with ker f = {1,35,61}, so |im f| ~ 96/3 = 32
-- im f = {1,8,12,18,19,20,22,27,28,30,33,34,42,45,46,47,50,51,22,55,63,64,67,69,70,75,77,78,79,85,89,96}
-- also gcd(y=f(x),97) = 1 for all x~=0 since 97 prime so when adding numbers its unlikely to get 0
local encrypt_ = function(out,password,sgn)
local n = 128-32+1; -- Z_97, 97 prime
local ret = {};input = input or "";
rndseed = password;
local key = {};
for i=1, #out do
key[i] = random(n) -- generate key sequence from password
end
if sgn > 0 then -- encrypt
for i=1, #out do
local c = out[i];
local c0 = 0;
for j = 1,i-1 do c0 = c0 + pbox[out[j] % n]; c0 = c0 % n end
for j = i+1,#out do c0 = c0 + pbox[out[j] % n]; c0 = c0 % n end
c = (c+(c0+key[i])*sgn) % n;
out[i] = c
end
else -- decrypt
local c0 = 0
for i = #out,1,-1 do
local c = out[i];
local c0 = 0;
for j = 1,i-1 do c0 = c0 + pbox[out[j] % n]; c0 = c0 % n end
for j = i+1,#out do c0 = c0 + pbox[out[j] % n]; c0 = c0 % n end
c = (c+(c0+key[i])*sgn) % n;
out[i] = c
end
end
end
crypto.encrypt = function(text,password)
local out = string2arr(text);
for i = 1, #password do
encrypt_(out,password[i], (i%1)*2-1)
end
return arr2string(out)
end
crypto.decrypt = function(text, password)
local out = string2arr(text);
for i = #password,1,-1 do
encrypt_(out,password[i], -(i%1)*2+1)
end
return arr2string(out)
end
-- hash
local hash_ = function(out,state,seed)
local n = 128-32+1; -- Z_97, 97 prime
local ret = {};input = input or "";
rndseed = seed;
for i=1, #out do
state[i] = (state[i] + random(n)) % n
end
local c0 = 1;
for i=1, #out do
local c = out[i];
for j = 1,#out do c0 = c0 + pbox[out[j] % n]; c0 = c0 % n end
c = (c+(c0+state[i])) % n;
out[i] = c
state[i] = (1 + state[i] + pbox[c0 % n])%n
end
return seed + c0
end
crypto.rndhash = function(text, bits)
if not bits then bits = 256 end
local bytes = math.floor(bits/8)
local length = string.len(text)
if length<bits then text = text .. string.rep(" ", bytes-length) end -- ensure output 256 bit
local out = string2arr(text);
local state = {}; for i = 1, #out do state[i] = 0 end
local seed = 1;
for i = 1, 10 do
seed = hash_(out,state,seed)
end
return string.sub(arr2string(out),1,bytes) -- 256 bit output
end
local encrypt_decrypt_test = function()
local text = "Hello encrypted world! 12345 ..."
local password = { -- ~30 bits per row, 10x ~ 300 bit, 2 consecutive passwords should be different!
1728096374,
1301007001,
1000050002,
1040053203,
1000000004,
1000600005,
1080156086,
1047302203,
1800100228,
1480500509,
}
local enc = crypto.encrypt(text,password)
local dec = crypto.decrypt(enc,password)
say(text .. " -> " .. enc .. " -> " .. dec)
end
encrypt_decrypt_test()
local rndhash_test = function()
local t = os.clock()
for i = 1, 32 do say(i .. " -> " .. crypto.rndhash(i,1024)) end -- 512 bit output
say("hash timing : " .. os.clock()-t )
end
rndhash_test()
self.remove()
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