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B4X

Set JWE Additional Authenticated Data

See more JSON Web Encryption (JWE) Examples

Demonstrates Jwe.SetAad, which sets external Additional Authenticated Data (AAD) for a JWE being encrypted, encoding the supplied text with the given charset.

Background. AAD is integrity-protected but not encrypted, binding external context to the ciphertext. The same AAD must be supplied again when decrypting.

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B4X
Dim success As Boolean = False

Dim jwe As ChilkatJwe
jwe.Initialize

'  Protected header: AES key-wrap with AES-256-GCM content encryption.
Dim header As ChilkatJsonObject
header.Initialize
header.UpdateString("alg", "A256KW")
header.UpdateString("enc", "A256GCM")
success = jwe.SetProtectedHeader(header)
If success = False Then
    Log(jwe.LastErrorText)
    Return
End If


'  The 256-bit key-wrapping key (base64) for recipient index 0.  In production, obtain the key from a
'  secure source rather than hard-coding it.
Dim base64Key As String = "YWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4eXowMTIzNDU="
success = jwe.SetWrappingKey(0, base64Key, "base64")
If success = False Then
    Log(jwe.LastErrorText)
    Return
End If


'  Set external Additional Authenticated Data (AAD).  The AAD is integrity-protected but not
'  encrypted, and must be supplied again when decrypting.
success = jwe.SetAad("context-info-v1", "utf-8")
If success = False Then
    Log(jwe.LastErrorText)
    Return
End If


Dim sbContent As ChilkatStringBuilder
sbContent.Initialize
sbContent.Append("This is the secret content.")
Dim sbJwe As ChilkatStringBuilder
sbJwe.Initialize
success = jwe.EncryptSb(sbContent, "utf-8", sbJwe)
If success = False Then
    Log(jwe.LastErrorText)
    Return
End If

Log(sbJwe.GetAsString)