Lua

Example: Hash Text in Chunks

Shows how to generate a final hash, like SHA-256, for a large text by processing it in chunks. Lua

local chilkat = require("chilkat")

local crypt = chilkat.Crypt2.new()
crypt.hash_algorithm = "sha256"
crypt.charset = "utf-8"

local bd = chilkat.BinData.new()

local s = "The quick brown fox jumped over the lazy dog.\r\n"

-- Accumulate the text in a StringBuilder.  We'll demonstrate hashing the text in chunks,
-- and then also hashing the entire text at once to show the results are the same.

bd:append_string(s, "utf-8")
local success = crypt:hash_begin_string(s)

local i = 0
while i < 200 do
    bd:append_string(s, "utf-8")
    crypt:hash_more_string(s)
    i = i + 1
end

-- Get the hash in base64 format.
crypt.encoding_mode = "base64"

local encodedHash = crypt:hash_final_enc()
print("Hash computed in chunks: " .. encodedHash)

-- Let's alternatively compute the hash of the entire amount of data at once,
-- to show the hash computation is the same:
encodedHash = crypt:hash_bd_enc(bd)
print("Hash computed in 1 step: " .. encodedHash)

-- Output:

-- Hash computed in chunks: unwkVff61k40roRIJizaknreScHaL6frWe37kydXbZQ=
-- Hash computed in 1 step: unwkVff61k40roRIJizaknreScHaL6frWe37kydXbZQ=