B4X

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.

Note: This example requires Chilkat v9.5.0.83 or greater.

B4X

Dim success As Boolean = False

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

Dim eddsa As ChilkatEdDSA
eddsa.Initialize
Dim prng As ChilkatPrng
prng.Initialize
Dim privKey As ChilkatPrivateKey
privKey.Initialize("privKey")

'  Generates a new ed25519 key and stores it in privKey.
success = eddsa.GenEd25519Key(prng, privKey)
If success = False Then
    Log(eddsa.LastErrorText)
    Return
End If


'  ----------------------------------------------------------
'  Ed25519 PKCS1 format
'  
'  This is the format created by:  openssl genpkey -algorithm X25519 -out xkey.pem
Dim pkcs1Base64 As String = privKey.GetPkcs1ENC("base64")
Log(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.SavePkcs1File("qa_output/ed25519.key")

'  ----------------------------------------------------------
'  Ed25519 Unencrypted PKCS8 format
'  
'  For ed25519, the ASN.1 output is the same as for PKCS1.
Dim pkcs8Base64 As String = privKey.GetPkcs8ENC("base64")
Log(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.
Dim password As String = "secret"
Dim pkcs8EncBase64 As String = privKey.GetPkcs8EncryptedENC("base64", password)
Log(pkcs8EncBase64)

'  ----------------------------------------------------------
'  Ed25519 in PEM format:
'  
Dim ed25519Pem As String = privKey.GetPkcs1Pem
Log(ed25519Pem)

'  Sample output:

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

'  ----------------------------------------------------------
'  Ed25519 in JWK Format
'  
Dim jwk As String = privKey.GetJwk

Dim json As ChilkatJsonObject
json.Initialize
json.Load(jwk)
json.EmitCompact = False
Log(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
'  
Dim ed25519_xml As String = privKey.GetXml
Log(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
'  
Dim sbPubKeyHex As ChilkatStringBuilder
sbPubKeyHex.Initialize
Dim privKeyHex As String = privKey.GetRawHex(sbPubKeyHex)

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

'  We should have a 32-byte public key (a 64 character hex string).
Log("public key = " & sbPubKeyHex.GetAsString)

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