Lua Requires Chilkat v9.5.0.77+

HOTP Algorithm: HMAC-Based One-Time Password Algorithm

See more Encryption Examples

Demonstrates how to generate an HMAC one-time password (HOTP) as specified in RFC 4226. Lua

local chilkat = require("chilkat")

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

local crypt = chilkat.Crypt2.new()

-- Duplicate the following results from RFC 4226

-- Appendix D - HOTP Algorithm: Test Values
--
--   The following test data uses the ASCII string
--   "12345678901234567890" for the secret:
--
--   Secret = 0x3132333435363738393031323334353637383930
--
--                     Truncated
--   Count    Hexadecimal    Decimal        HOTP
--   0        4c93cf18       1284755224     755224
--   1        41397eea       1094287082     287082
--   2         82fef30        137359152     359152
--   3        66ef7655       1726969429     969429
--   4        61c5938a       1640338314     338314
--   5        33c083d4        868254676     254676
--   6        7256c032       1918287922     287922
--   7         4e5b397         82162583     162583
--   8        2823443f        673399871     399871
--   9        2679dc69        645520489     520489

local secret = "12345678901234567890"
for count = 0, 9 do
    local counterHex = crypt:encode_int(count, 8, false, "hex")
    local hotp = crypt:hotp(secret, "ascii", counterHex, 6, -1, "sha1")
    print(count .. "  HOTP = " .. hotp)
end

-- Output is:
-- 0  HOTP = 755224
-- 1  HOTP = 287082
-- 2  HOTP = 359152
-- 3  HOTP = 969429
-- 4  HOTP = 338314
-- 5  HOTP = 254676
-- 6  HOTP = 287922
-- 7  HOTP = 162583
-- 8  HOTP = 399871
-- 9  HOTP = 520489