(Visual FoxPro) JWE using "dir" Direct use of Shared Symmetric Key

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.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

LOCAL lnSuccess
LOCAL lcPlaintext
LOCAL loJwe
LOCAL loJweProtHdr
LOCAL lnRecipientIndex
LOCAL lcStrJwe
LOCAL loJwe2
LOCAL lcOriginalPlaintext

* 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.

lcPlaintext = "Live long and prosper."

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Jwe')
loJwe = CreateObject('Chilkat.Jwe')

* First build the JWE Protected Header..
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.JsonObject')
loJweProtHdr = CreateObject('Chilkat.JsonObject')
loJweProtHdr.AppendString("alg","dir")
loJweProtHdr.AppendString("enc","A128GCM")

* Don't forget to actually provide the protected header to the JWE object:
loJwe.SetProtectedHeader(loJweProtHdr)

* 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.

lnRecipientIndex = 0
loJwe.SetWrappingKey(lnRecipientIndex,"000102030405060708090A0B0C0D0E0F","hex")

* Encrypt and return the JWE:
lcStrJwe = loJwe.Encrypt(lcPlaintext,"utf-8")
IF (loJwe.LastMethodSuccess <> 1) THEN
    ? loJwe.LastErrorText
    RELEASE loJwe
    RELEASE loJweProtHdr
    CANCEL
ENDIF

* Show the JWE we just created:
? lcStrJwe

* Decrypt the JWE.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Jwe')
loJwe2 = CreateObject('Chilkat.Jwe')
lnSuccess = loJwe2.LoadJwe(lcStrJwe)
IF (lnSuccess <> 1) THEN
    ? loJwe2.LastErrorText
    RELEASE loJwe
    RELEASE loJweProtHdr
    RELEASE loJwe2
    CANCEL
ENDIF

loJwe2.SetWrappingKey(0,"000102030405060708090A0B0C0D0E0F","hex")

* Decrypt.
lcOriginalPlaintext = loJwe2.Decrypt(0,"utf-8")
IF (loJwe2.LastMethodSuccess <> 1) THEN
    ? loJwe2.LastErrorText
    RELEASE loJwe
    RELEASE loJweProtHdr
    RELEASE loJwe2
    CANCEL
ENDIF

? "original text: "
? lcOriginalPlaintext

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

RELEASE loJwe
RELEASE loJweProtHdr
RELEASE loJwe2