Lua Requires Chilkat v9.5.0.70+

Hash a Hex String

See more Encryption Examples

Demonstrates common pitfalls in hashing a hex string.. Lua

local chilkat = require("chilkat")

-- This example assumes the Chilkat API to have been previously unlocked.
-- See Global Unlock Sample for sample code.

local crypt = chilkat.Crypt2.new()

-- We have a hex string to be SHA-256 hashed:  "b08538d832bf"
-- The result we expect to receive is "8a9f04cb1adfbd7f59c5918635f92f6c847e5b15f9828519d2fdbd6ead0918fc"

local strToHash = "b08538d832bf"

-- How do we get this result?

-- The 1st question to be answered is:  What bytes are getting hashed?
-- There are two possibilities:
-- 1) Hash 12 bytes, namely the us-ascii values for 'b', '0', '8', '5', .... 'b', 'f'
-- or
-- 2) Hash 6 bytes:  0xb0, 0x85, ... 0xbf
--

-- This is how to hash the 12 us-ascii byte values:
-- The Charset property defines the byte representation of the string passed to the hash algorithm:
crypt.charset = "us-ascii"
-- The EncodingMode property defines the binary encoding (hex, base64, etc.) of the hash returned as an encoded string.
crypt.encoding_mode = "hex"
crypt.hash_algorithm = "sha256"

local hashValue = crypt:hash_string_enc(strToHash)
print(crypt.last_error_text)
print("hash of 12 us-ascii bytes: " .. hashValue)

-- The result is:  327F2B33A0F0580D09840B0D7CEE54514CA33E9A  (not what we were hoping).

-- -------------------------------------------
-- This is how to hash the 6 bytes
--
-- "hex" is not an actual character encoding.  It's a special value to be used to tell Chilkat to hex decode
-- the string and pass the decoded bytes to the hash algorithm...
crypt.charset = "hex"
-- The EncodingMode and HashAlgorithm remain the same..
hashValue = crypt:hash_string_enc(strToHash)
print(crypt.last_error_text)
print("hash of 6 hex bytes: " .. hashValue)

-- The result is 8A9F04CB1ADFBD7F59C5918635F92F6C847E5B15F9828519D2FDBD6EAD0918FC (which equals the hash we were expecting)