I would recommend against using SHA256 for passwords. They are easy to bruteforce nowadays, and the way you are using them is vulnerable to replay attacks.
Also if you must use SHA256, use the version from OpenSSL if possible (especially if your program already depends on OpenSSL.)
But if you must use it (and cannot link with OpenSSL, but can use FFI) here is a LuaJIT version of SHA256 (only) that I am using in one of my projects.
local bit = require 'bit'
local ffi = require 'ffi'
local type = type
local band, bnot, bswap, bxor, rol, ror, rshift, tobit =
bit.band, bit.bnot, bit.bswap, bit.bxor, bit.rol, bit.ror, bit.rshift, bit.tobit
local min, max = math.min, math.max
local C = ffi.C
local istype, new, fill, copy, cast, sizeof, ffi_string =
ffi.istype, ffi.new, ffi.fill, ffi.copy, ffi.cast, ffi.sizeof, ffi.string
local sha256 = {}
ffi.cdef [[
void *malloc(size_t size);
void free(void *ptr);
]]
local ctHashState = ffi.typeof 'uint32_t[8]'
local cbHashState = ffi.sizeof(ctHashState)
local ctBlock = ffi.typeof 'uint32_t[64]'
local cbBlock = ffi.sizeof(ctBlock)
local ctpu8 = ffi.typeof 'uint8_t *'
local ctpcu8 = ffi.typeof 'const uint8_t *'
local ctpu32 = ffi.typeof 'uint32_t *'
local ctpu64 = ffi.typeof 'uint64_t *'
-- This struct is used by the 'preprocess' iterator function. It keeps track
-- of the end of the input string + the total input length in bits + a pointer
-- to the block buffer (where expansion takes place.)
local ctBlockIter
local cmtBlockIter = {}
function cmtBlockIter.__sub(a, b)
if istype(ctBlockIter, a) then a = a.limit end
if istype(ctBlockIter, b) then b = b.limit end
return a - b
end
function cmtBlockIter:__tostring()
return string.format("<ctBlockIter: limit=%s; keyLength=%s>",
tostring(self.base), tostring(self.keyLength))
end
ctBlockIter = ffi.metatype([[
struct {
const uint8_t *limit;
uint32_t *blockBuffer;
uint64_t keyLength;
}
]], cmtBlockIter)
-- Initial state of the hash
local init_h = new('const uint32_t[8]', {
0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a,
0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19
})
-- Constants used in the add step of the compression function
local k = new('const uint32_t[64]', {
0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
})
-- Expand block from 512 to 2048 bits
local function expand(w)
for i = 16, 63 do
local s0 = bxor(ror(w[i-15], 7), ror(w[i-15], 18), rshift(w[i-15], 3))
local s1 = bxor(ror(w[i-2], 17), ror(w[i-2], 19), rshift(w[i-2], 10))
w[i] = w[i-16] + s0 + w[i-7] + s1
end
end
-- Process one expanded block and update the hash state
local function compress(hh, w)
local a, b, c, d, e, f, g, h =
hh[0],hh[1],hh[2],hh[3],hh[4],hh[5],hh[6],hh[7]
for i = 0, 63 do
local S1 = bxor(ror(e, 6), ror(e, 11), ror(e, 25))
local ch = bxor(band(e, f), band(bnot(e), g))
local t = tobit(h + S1 + ch + k[i] + w[i])
local S0 = bxor(ror(a, 2), ror(a, 13), ror(a, 22))
local maj = bxor(band(a, bxor(b, c)), band(b, c))
a, b, c, d, e, f, g, h =
tobit(t + S0 + maj),
a, b, c,
tobit(d + t),
e, f, g
end
hh[0],hh[1],hh[2],hh[3],hh[4],hh[5],hh[6],hh[7] =
hh[0]+a, hh[1]+b, hh[2]+c, hh[3]+d,
hh[4]+e, hh[5]+f, hh[6]+g, hh[7]+h
end
-- Take a 512-bit chunk from the input.
-- If it is the final chunk, also add padding
local keyLengthOfs = ffi.offsetof(ctBlockIter, 'keyLength')
local function nextBlock(state, input)
local w = state.blockBuffer
local cLen = min(state - input, 64)
if cLen < -8 then return nil end
fill(w, 256, 0)
copy(w, input, max(0, cLen))
if 0 <= cLen and cLen < 64 then
copy(cast(ctpu8, w)+cLen, '\128', 1)
end
for i = 0, 15 do w[i] = bswap(w[i]) end
if cLen <= (64-8-1) then
copy(cast(ctpu64, w) + 7, cast(ctpu8, state) + keyLengthOfs, 8)
w[14], w[15] = w[15], w[14]
end
input = input + 64
return input
end
-- Iterator that yields one block (possibly padded) at a time from the input
local function preprocess(input, len, w)
len = len or (type(input) == 'string' and #input or sizeof(input))
input = cast(ctpu8, input)
local it = new(ctBlockIter)
it.blockBuffer = w
it.limit = input+len
it.keyLength = len*8
return nextBlock, it, input
end
-- Compute a binary hash (32-byte binary string) from the input
function sha256.binFromBin(input, len)
local h = new(ctHashState)
local w = cast(ctpu32, C.malloc(cbBlock))
copy(h, init_h, cbHashState)
for _ in preprocess(input, len, w) do
expand(w)
compress(h, w)
end
for i = 0, 7 do h[i] = bswap(h[i]) end
C.free(w)
return ffi_string(h, 32)
end
local hexDigits = new('char[16]', "0123456789abcdef")
local hexOut = new('char[65]')
-- Compute the hash and convert to hexadecimal
function sha256.hexFromBin(input, len)
local h = new(ctHashState)
local w = cast(ctpu32, C.malloc(cbBlock))
copy(h, init_h, cbHashState)
for _ in preprocess(input, len, w) do
expand(w)
compress(h, w)
end
for i = 0, 7 do
local w = h[i]
for j = 0, 3 do
w = rol(w, 8)
hexOut[i*8 + j*2] = hexDigits[band(rshift(w, 4), 15)]
hexOut[i*8 + j*2 + 1] = hexDigits[band(w, 15)]
end
end
C.free(w)
return ffi_string(hexOut, 64)
end
return sha256
