B4X

JWE using ECDH-ES+A256KW

See more JSON Web Encryption (JWE) Examples

Create a JWE with the following public/private key pair:

{
    "kty": "EC",
    "d": "jZCffzVqJjryBH4EoaN0oD-TyLXrW2XHoDdIuPZnk8c",
    "use": "enc",
    "crv": "P-256",
    "kid": "evEK2thJMsWxBYRivXI8ykUf6n6zizLiLCGH3s58wKs",
    "x": "LOakgGvxWBsWbCPLY6Vq6OuBktIqG8POXFXe7ngQ2oM",
    "y": "voJvS6I-Mc4qqmEA_G2hLQqBck3a3vqaJbmzY7YPUD4",
    "alg": "ECDH-ES+A256KW"
}

Also shows how to decrypt.

B4X

Dim success As Boolean = False

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

'  Create the following JSON:
'  {
'      "kty": "EC",
'      "d": "jZCffzVqJjryBH4EoaN0oD-TyLXrW2XHoDdIuPZnk8c",
'      "use": "enc",
'      "crv": "P-256",
'      "kid": "evEK2thJMsWxBYRivXI8ykUf6n6zizLiLCGH3s58wKs",
'      "x": "LOakgGvxWBsWbCPLY6Vq6OuBktIqG8POXFXe7ngQ2oM",
'      "y": "voJvS6I-Mc4qqmEA_G2hLQqBck3a3vqaJbmzY7YPUD4",
'      "alg": "ECDH-ES+A256KW"
'  }

Dim json As ChilkatJsonObject
json.Initialize
json.UpdateString("kty", "EC")
json.UpdateString("d", "jZCffzVqJjryBH4EoaN0oD-TyLXrW2XHoDdIuPZnk8c")
json.UpdateString("use", "enc")
json.UpdateString("crv", "P-256")
json.UpdateString("kid", "evEK2thJMsWxBYRivXI8ykUf6n6zizLiLCGH3s58wKs")
json.UpdateString("x", "LOakgGvxWBsWbCPLY6Vq6OuBktIqG8POXFXe7ngQ2oM")
json.UpdateString("y", "voJvS6I-Mc4qqmEA_G2hLQqBck3a3vqaJbmzY7YPUD4")
json.UpdateString("alg", "ECDH-ES+A256KW")

Dim pubkey As ChilkatPublicKey
pubkey.Initialize

success = pubkey.LoadFromString(json.Emit)
If success = False Then
    Log(pubkey.LastErrorText)
    Return
End If


'  Build our protected header:

'  	{
'  	  "alg": "ECDH-ES+A256KW",
'  	  "enc": "A256GCM",
'  	  "exp": 1621957030,
'  	  "cty": "NJWT",
'  	  "epk": {
'  	    "kty": "EC",
'  	    "x": "QLpJ_LpFx-6yJhsb4OvHwU1khLnviiOwYOvmf5clK7w"
'  	    "y": "AJh7pJ3zZKDJkm8rbeG69GBooTosXJgSsvNFH0i3Vxnu"
'  	    "crv": "BP-256"
'  	  }
'  	}

'  Use jwt only for getting the current date/time + 3600 seconds.
Dim jwt As ChilkatJwt
jwt.Initialize

Dim jweProtHdr As ChilkatJsonObject
jweProtHdr.Initialize
jweProtHdr.UpdateString("alg", "ECDH-ES+A256KW")
jweProtHdr.UpdateString("enc", "A256GCM")
jweProtHdr.UpdateInt("exp", jwt.GenNumericDate(3600))
jweProtHdr.UpdateString("cty", "NJWT")
jweProtHdr.UpdateString("epk.kty", "EC")
jweProtHdr.UpdateString("epk.x", "LOakgGvxWBsWbCPLY6Vq6OuBktIqG8POXFXe7ngQ2oM")
jweProtHdr.UpdateString("epk.y", "voJvS6I-Mc4qqmEA_G2hLQqBck3a3vqaJbmzY7YPUD4")
jweProtHdr.UpdateString("epk.crv", "P-256")

Dim jwe As ChilkatJwe
jwe.Initialize
jwe.SetProtectedHeader(jweProtHdr)
jwe.SetPublicKey(0, pubkey)

Dim plainText As String = "This is the text to be encrypted."
Dim strJwe As String = jwe.Encrypt(plainText, "utf-8")
If jwe.LastMethodSuccess <> True Then
    Log(jwe.LastErrorText)
    Return
End If


Log(strJwe)

'  Let's decrypt...
Dim privkey As ChilkatPrivateKey
privkey.Initialize("privkey")

success = privkey.LoadJwk(json.Emit)
If success = False Then
    Log(privkey.LastErrorText)
    Return
End If


Dim jwe2 As ChilkatJwe
jwe2.Initialize
success = jwe2.LoadJwe(strJwe)
If success = False Then
    Log(jwe2.LastErrorText)
    Return
End If


jwe2.SetPrivateKey(0, privkey)

'   Decrypt.
Dim decryptedText As String = jwe2.Decrypt(0, "utf-8")
If jwe2.LastMethodSuccess <> True Then
    Log(jwe2.LastErrorText)
    Return
End If


Log(decryptedText)