(Visual FoxPro) JWE using A256GCMKW

This example demonstrates creating a JCE with AES GCM key wrap.

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

LOCAL lnSuccess
LOCAL lcPlaintext
LOCAL loJwe
LOCAL loJweProtHdr
LOCAL loPrng
LOCAL lcAesWrappingKey
LOCAL lcStrJwe
LOCAL loJwe2
LOCAL lcOriginalPlaintext

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

lcPlaintext = "My text to enrypt"

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

* First build the JWE Protected Header: 

*         {
*             "alg": "A256GCMKW",
*             "kid": "18ec08e1-bfa9-4d95-b205-2b4dd1d4321d",
*             "tag": "kfPduVQ3T3H6vnewt--ksw",
*             "iv": "KkYT0GX_2jHlfqN_",
*             "enc": "A128CBC-HS256"
*         }

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.JsonObject')
loJweProtHdr = CreateObject('Chilkat.JsonObject')
loJweProtHdr.AppendString("alg","A256GCMKW")
* kid is optional
loJweProtHdr.AppendString("kid","18ec08e1-bfa9-4d95-b205-2b4dd1d4321d")
* tag is optional
loJweProtHdr.AppendString("tag","kfPduVQ3T3H6vnewt--ksw")
loJweProtHdr.AppendString("enc","A256GCM")
* the iv should be 16 random chars.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Prng')
loPrng = CreateObject('Chilkat.Prng')
loJweProtHdr.AppendString("iv",loPrng.RandomString(16,1,1,1))
loJwe.SetProtectedHeader(loJweProtHdr)

? "JWE Protected Header: " + loJweProtHdr.Emit()
? "--"

* Given that we have 256-bit AES, our key should be 32 bytes.
* The ascii string here is 32 bytes, therefore the 2nd arg is "ascii" to use these
* ascii chars directly as the key.
lcAesWrappingKey = "2baf4f730f5e4542b428593ef9cceb0e"
loJwe.SetWrappingKey(0,lcAesWrappingKey,"ascii")

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

* Show the JWE we just created:
? lcStrJwe

* Decrypt the JWE that was just produced.
* 1) Load the JWE.
* 2) Set the AES wrapping key.
* 3) Decrypt.
* 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 loPrng
    RELEASE loJwe2
    CANCEL
ENDIF

* Set the AES wrap key.  Important to use "ascii"
loJwe2.SetWrappingKey(0,lcAesWrappingKey,"ascii")

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

? "original text: "
? lcOriginalPlaintext

RELEASE loJwe
RELEASE loJweProtHdr
RELEASE loPrng
RELEASE loJwe2