VB.NET

JWE using "dir" Direct use of Shared Symmetric Key

See more JSON Web Encryption (JWE) Examples

Demonstrates how to create a JWE using the "dir" alg -- which is to directly use a shared symmetric key.

Note: This example requires Chilkat v9.5.0.66 or greater.

VB.NET

Dim success As Boolean = False

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

' Note: This example requires Chilkat v9.5.0.66 or greater.

Dim plaintext As String = "Live long and prosper."

Dim jwe As New Chilkat.Jwe

' First build the JWE Protected Header..
Dim jweProtHdr As New Chilkat.JsonObject
jweProtHdr.AppendString("alg","dir")
jweProtHdr.AppendString("enc","A128GCM")

' Don't forget to actually provide the protected header to the JWE object:
jwe.SetProtectedHeader(jweProtHdr)

' The JWE is to use 128-bit AES GCM encryption as specified by the "enc" parameter.
' Given that the "alg" = "dir", we are to directly specify the AES GCM key.
' (It is assumed that the decrypting side also has knowledge of the direct key to be used..)

' Our key will be these 16 hex bytes: 000102030405060708090A0B0C0D0E0F

' The SetWrappingKey method is also used for "dir" direct keys.
' However, if there are multiple recipients, they must all share the same CEK (Content Encryption Key),
' which is specified by calling SetWrappingKey with an index of 0.

Dim recipientIndex As Integer = 0
jwe.SetWrappingKey(recipientIndex,"000102030405060708090A0B0C0D0E0F","hex")

' Encrypt and return the JWE:
Dim strJwe As String = jwe.Encrypt(plaintext,"utf-8")
If (jwe.LastMethodSuccess <> True) Then
    Debug.WriteLine(jwe.LastErrorText)
    Exit Sub
End If


' Show the JWE we just created:
Debug.WriteLine(strJwe)

' Decrypt the JWE.
Dim jwe2 As New Chilkat.Jwe
success = jwe2.LoadJwe(strJwe)
If (success <> True) Then
    Debug.WriteLine(jwe2.LastErrorText)
    Exit Sub
End If

jwe2.SetWrappingKey(0,"000102030405060708090A0B0C0D0E0F","hex")

' Decrypt.
Dim originalPlaintext As String = jwe2.Decrypt(0,"utf-8")
If (jwe2.LastMethodSuccess <> True) Then
    Debug.WriteLine(jwe2.LastErrorText)
    Exit Sub
End If


Debug.WriteLine("original text: ")
Debug.WriteLine(originalPlaintext)

' Sample output:
' eyJhbGciOiJkaXIiLCJlbmMiOiJBMTI4R0NNIn0..20HX5Huc7f1nQC4pBUtiCQ.axFZIxtZy5j0ifJQUzGXLKIpsBuxJA.eBrOC-NrsreN6JeGuOPk1g
' original text: 
' Live long and prosper.