SHA1

-- SHA1
-- By KillaVanilla

local function Preprocessing(msg)
    local msgCp = {}
    local lastPause = os.clock()
    for i=1, #msg do
        msgCp[i] = msg[i]
        if (os.clock() - lastPause) >= 2.90 then
            os.queueEvent("")
            os.pullEvent("")
            lastPause = os.clock()
        end
    end
    local len = #msgCp*8
    local bits = #msgCp*8
    table.insert(msgCp, 0x80)
    while true do
        if bits % 512 == 448 then
            break
        else
            table.insert(msgCp, 0)
            bits = #msgCp*8
        end
    end
    table.insert(msgCp, len)
    return msgCp
end

local function breakMsg(message)
    local chunks = {}
    local chunk = 1
    for word=1, #message, 16 do
        chunks[chunk] = {}
        for i2=0, 15 do
            table.insert(chunks[chunk], message[word+i2] or 0)
        end
        chunk = chunk+1
    end
    return chunks
end

function leftrotate(a, i)
    local bitmask = (2^i)-1
    local shiftOut = bit.band(a, bit.blshift(bitmask, 32-i))
    if bit.band(shiftOut, 0x80000000) > 0 then -- gotta work around the arithmetic right shift
        --[[
        shiftOut = bit.brshift(shiftOut, 1)
        shiftOut = bit.band(shiftOut, 0x7FFFFFFF)
        shiftOut = bit.brshift(shiftOut, 31-i)
        ]]
        shiftOut = bit.band(bit.brshift(shiftOut, 32-i), bitmask)
    else
        shiftOut = bit.brshift(shiftOut, 32-i)
    end
    local b = bit.band(bit.blshift(a, i), 0xFFFFFFFF)
    b = bit.bor(b, shiftOut)
    return (b  % (2^32))
end

function digest(bytes, debugFile)
    bytes = Preprocessing(bytes)
    local chunks = breakMsg(bytes)
    local h = {}
    h[0] = 0x67452301
    h[1] = 0xEFCDAB89
    h[2] = 0x98BADCFE
    h[3] = 0x10325476
    h[4] = 0xC3D2E1F0
    local debug = false
    if debugFile then
        debug = fs.open(debugFile, "w")
    end
    local pauseTimer1 = os.clock()
    for chunkN=1, #chunks do
        local w = {}
        for i=0, 15 do
            w[i] = chunks[chunkN][i+1]
        end
        local pauseTimer2 = os.clock()
        for i=16, 79 do
            w[i] = bit.bxor( bit.bxor(w[i-3], w[i-8]), bit.bxor(w[i-14], w[i-16]) ) % (2^32)
            w[i] = leftrotate(w[i], 1)
            if (os.clock() - pauseTimer2) >= 2.5 then
                os.queueEvent("")
                os.pullEvent("")
                pauseTimer2 = os.clock()
            end
        end
        local a = h[0]
        local b = h[1]
        local c = h[2]
        local d = h[3]
        local e = h[4]
        local pauseTimer3 = os.clock()
        for i=0, 79 do
            local f = 0
            local k = 0
            if (i >= 0) and (i <= 19) then
                f = bit.bor(bit.band(a, c), bit.band(bit.bnot(b), d)) % (2^32)
                k = 0x5A827999
            elseif (i >= 20) and (i <= 39) then
                f = bit.bxor(b, bit.bxor(c, d)) % (2^32)
                k = 0x6ED9EBA1
            elseif (i >= 40) and (i <= 59) then
                f = bit.bor(bit.band(b, c), bit.bor(bit.band(b, d), bit.band(c, d))) % (2^32)
                k = 0x8F1BBCDC
            elseif (i >= 60) and (i <= 79) then
                f = bit.bxor(b, bit.bxor(c, d)) % (2^32)
                k = 0xCA62C1D6
            end
            local temp = (leftrotate(a, 5)+f+e+k+w[i]) % (2^32)
            e = d
            d = c
            c = leftrotate(b, 30)
            b = a
            a = temp
            if (os.clock() - pauseTimer3) >= 2.80 then
                os.queueEvent("")
                os.pullEvent("")
                pauseTimer3 = os.clock()
            end
        end
        h[0] = (h[0]+a) % (2^32)
        h[1] = (h[1]+b) % (2^32)
        h[2] = (h[2]+c) % (2^32)
        h[3] = (h[3]+d) % (2^32)
        h[4] = (h[4]+e) % (2^32)
        if debug then
            debug.writeLine(chunkN..": "..string.format("%X", h[0]).."|"..string.format("%X", h[1]).."|"..string.format("%X", h[2]).."|"..string.format("%X", h[3]).."|"..string.format("%X", h[4]))
        end
        if (os.clock() - pauseTimer1) >= 2.80 then
            os.queueEvent("")
            os.pullEvent("")
            pauseTimer1 = os.clock()
        end
    end
    if debug then
        debug.close()
    end
    local hash = {}
    for i=0, 4 do
        table.insert(hash, h[i])
    end
    return hash
end

function digestStr(str, debugFile)
    local msg = {}
    for i=1, #str do
        msg[i] = string.byte(str, i, i)
    end
    return digest(msg, debugFile)
end

function digest2str(d)
    local str = ""
    for i=1, #d do
        str = str..string.format("%X", d[i])
    end
    return str
end

function digest2bytes(d)
    local bytes = {}
    for i=1, #d do
        table.insert(bytes, bit.band(bit.brshift(bit.band(d[i], 0xFF000000), 24), 0xFF))
        table.insert(bytes, bit.band(bit.brshift(bit.band(d[i], 0xFF0000), 16), 0xFF))
        table.insert(bytes, bit.band(bit.brshift(bit.band(d[i], 0xFF00), 8), 0xFF))
        table.insert(bytes, bit.band(d[i], 0xFF))
    end
    return bytes
end