Lua Requires Chilkat v9.5.0.83+

Get Ed25519 Key in Different Formats

See more Ed25519 Examples

Demonstrates how to get/save an Ed25519 private key to different formats.

Converting a private key from one format to another is done by loading in one format and saving/getting in another.

Lua

local chilkat = require("chilkat")

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

local eddsa = chilkat.EdDSA.new()
local prng = chilkat.Prng.new()
local privKey = chilkat.PrivateKey.new()

-- Generates a new ed25519 key and stores it in privKey.
local success = eddsa:gen_ed25519_key(prng, privKey)
if not success then
    print(eddsa.last_error_text)
    return
end

-- ----------------------------------------------------------
-- Ed25519 PKCS1 format
--
-- This is the format created by:  openssl genpkey -algorithm X25519 -out xkey.pem
local pkcs1Base64 = privKey:get_pkcs1_enc("base64")
print(pkcs1Base64)

-- Sample output:  MC4CAQAwBQYDK2VuBCIEIB1mwirs+eC6XGbkjPIiZyBwQ7768uSd9v5PHOLFbIXo

-- PKCS1 is a binary ASN.1 DER format.  You can examine the contents with two online tools:
-- 1) Go to ASN.1 Decoder  and paste the base64 into the online form.
-- 2) Or Decode Base64 ASN.1 to XML

-- The PKCS1 ASN.1 format for an Ed25519 key look like this:
--   SEQUENCE
--     INTEGER 0
--     SEQUENCE
--       OBJECT IDENTIFIER 1.3.101.110 curveX25519 (ECDH 25519 key agreement algorithm)
--     OCTET STRING
--       OCTET STRING (32 byte) 1D66C...

-- Save it directly to a file.
success = privKey:save_pkcs1_file("qa_output/ed25519.key")

-- ----------------------------------------------------------
-- Ed25519 Unencrypted PKCS8 format
--
-- For ed25519, the ASN.1 output is the same as for PKCS1.
local pkcs8Base64 = privKey:get_pkcs8_enc("base64")
print(pkcs8Base64)

-- PKCS8 is a binary ASN.1 DER format.  You can examine the contents with two online tools:
-- 1) Go to ASN.1 Decoder  and paste the base64 into the online form.
-- 2) Or Decode Base64 ASN.1 to XML

-- ----------------------------------------------------------
-- Ed25519 Encrypted PKCS8 format
--
-- Note: The encrypted output cannot be examined using the above online tools because the ASN.1 is encrypted.
local password = "secret"
local pkcs8EncBase64 = privKey:get_pkcs8_encrypted_enc("base64", password)
print(pkcs8EncBase64)

-- ----------------------------------------------------------
-- Ed25519 in PEM format:
--
local ed25519Pem = privKey:get_pkcs1_pem()
print(ed25519Pem)

-- Sample output:

-- -----BEGIN PRIVATE KEY-----
-- MC4CAQAwBQYDK2VuBCIEIOKPhbULJagBAi7hbRdn1f4AAzh1RqqCHqCAvau7N6yO
-- -----END PRIVATE KEY-----

-- ----------------------------------------------------------
-- Ed25519 in JWK Format
--
local jwk = privKey:get_jwk()

local json = chilkat.JsonObject.new()
json:load(jwk)
json.emit_compact = false
print(json:emit())

-- Sample output:
-- {
--   "kty": "OKP",
--   "crv": "Ed25519",
--   "x": "SE2Kne5xt51z1eciMH2T2ftDQp96Gl6FhY6zSQujiP0",
--   "d": "O-eRXewadF0sNyB0U9omcnt8Qg2ZmeK3WSXPYgqe570",
--   "use": "sig"
-- }

-- In the above JWK, x is the public key, y is the private key.
-- Both are 32 bytes and are base64-url encoded.

-- ----------------------------------------------------------
-- Ed25519 in XML Format
--
local ed25519_xml = privKey:get_xml()
print(ed25519_xml)

-- Sample output:  <Ed25519KeyValue>w4b/gI0zgYKgjtfWLjNfc4issmP7Qap84uesYNgEefP/WoY3jNOhOzgTYsMtOnuyGn3MdA4NZtsUXVNI1NiTlA==</Ed25519KeyValue>

-- The base64 content is composed of the concatenation of the 32-byte private key with the 32-byte public key and then base64 encoded.
-- In other words:  Base64(privKey || pubKey)

-- ----------------------------------------------------------
-- Ed25519 in Raw Hex Format
--
local sbPubKeyHex = chilkat.StringBuilder.new()
local privKeyHex = privKey:get_raw_hex(sbPubKeyHex)

-- We should have a 32-byte private key (a 64 character hex string).
print("private key = " .. privKeyHex)

-- We should have a 32-byte public key (a 64 character hex string).
print("public key = " .. sbPubKeyHex:get_as_string())

-- Sample output:
-- key type = ed25519
-- size in bits = 256
-- private key = d4ee72dbf913584ad5b6d8f1f769f8ad3afe7c28cbf1d4fbe097a88f44755842
-- public key = 19bf44096984cdfe8541bac167dc3b96c85086aa30b6b6cb0c5c38ad703166e1