(Visual FoxPro) JWE with DEFLATE Compression

Demonstrates how to DEFLATE ("zip") compress the JWE payload prior to encryption.

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 loSbPlainText
LOCAL lnBCrLf
LOCAL lcLine
LOCAL loJwe
LOCAL loJweProtHdr
LOCAL lcAesWrappingKey
LOCAL loSbJweCompressed
LOCAL loSbJweUncompressed
LOCAL loJwe2
LOCAL loSbOriginalText

* 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.

* Create some plaintext to be encrypted.
* This example will demonstrate with and without DEFLATE (zip) compression.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.StringBuilder')
loSbPlainText = CreateObject('Chilkat.StringBuilder')
lnBCrLf = 1
lcLine = "Live long and prosper."
loSbPlainText.AppendLine(lcLine,lnBCrLf)
loSbPlainText.AppendLine(lcLine,lnBCrLf)
loSbPlainText.AppendLine(lcLine,lnBCrLf)
loSbPlainText.AppendLine(lcLine,lnBCrLf)

* The text to be encrypted:
? loSbPlainText.GetAsString()

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

* Build the JWE Protected Header: {"alg":"A128KW","enc":"A128CBC-HS256","zip":"DEF"}
* The "zip":"DEF" parameter indicates that the plaintext payload should
* be compressed prior to encryption.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.JsonObject')
loJweProtHdr = CreateObject('Chilkat.JsonObject')
loJweProtHdr.AppendString("alg","A128KW")
loJweProtHdr.AppendString("enc","A128CBC-HS256")
loJweProtHdr.AppendString("zip","DEF")
loJwe.SetProtectedHeader(loJweProtHdr)

* Set the AES key wrap key:
lcAesWrappingKey = "GawgguFyGrWKav7AX4VKUg"
loJwe.SetWrappingKey(0,lcAesWrappingKey,"base64url")

* Encrypt and return the JWE in sbJweCompressed:
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.StringBuilder')
loSbJweCompressed = CreateObject('Chilkat.StringBuilder')
lnSuccess = loJwe.EncryptSb(loSbPlainText,"utf-8",loSbJweCompressed)
IF (lnSuccess <> 1) THEN
    ? loJwe.LastErrorText
    RELEASE loSbPlainText
    RELEASE loJwe
    RELEASE loJweProtHdr
    RELEASE loSbJweCompressed
    CANCEL
ENDIF

* Show the compressed JWE:
? loSbJweCompressed.GetAsString()
? "size of compressed JWE: " + STR(loSbJweCompressed.Length)

* Now create a JWE without compression.
loJweProtHdr.Delete("zip")
* Make sure to update the shared protected header:
loJwe.SetProtectedHeader(loJweProtHdr)

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.StringBuilder')
loSbJweUncompressed = CreateObject('Chilkat.StringBuilder')
lnSuccess = loJwe.EncryptSb(loSbPlainText,"utf-8",loSbJweUncompressed)
IF (lnSuccess <> 1) THEN
    ? loJwe.LastErrorText
    RELEASE loSbPlainText
    RELEASE loJwe
    RELEASE loJweProtHdr
    RELEASE loSbJweCompressed
    RELEASE loSbJweUncompressed
    CANCEL
ENDIF

* Show the uncompressed JWE:
? loSbJweUncompressed.GetAsString()
? "size of uncompressed JWE: " + STR(loSbJweUncompressed.Length)

* Decrypting is the same whether compression is used or not.
* The "zip" header in the JWE indicates that the payload should be 
* automatically decompressed (inflated) after decrypting.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Jwe')
loJwe2 = CreateObject('Chilkat.Jwe')
lnSuccess = loJwe2.LoadJweSb(loSbJweCompressed)
IF (lnSuccess <> 1) THEN
    ? loJwe2.LastErrorText
    RELEASE loSbPlainText
    RELEASE loJwe
    RELEASE loJweProtHdr
    RELEASE loSbJweCompressed
    RELEASE loSbJweUncompressed
    RELEASE loJwe2
    CANCEL
ENDIF

* Set the AES wrap key.
loJwe2.SetWrappingKey(0,lcAesWrappingKey,"base64url")

* Decrypt (also automatically decompresses).
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.StringBuilder')
loSbOriginalText = CreateObject('Chilkat.StringBuilder')
lnSuccess = loJwe2.DecryptSb(0,"utf-8",loSbOriginalText)
IF (lnSuccess <> 1) THEN
    ? loJwe2.LastErrorText
    RELEASE loSbPlainText
    RELEASE loJwe
    RELEASE loJweProtHdr
    RELEASE loSbJweCompressed
    RELEASE loSbJweUncompressed
    RELEASE loJwe2
    RELEASE loSbOriginalText
    CANCEL
ENDIF

? "original text from compressed JWE: "
? loSbOriginalText.GetAsString()

* -----------------------------------------------------------
* Do the same with the uncompressed JWE

lnSuccess = loJwe2.LoadJweSb(loSbJweUncompressed)
IF (lnSuccess <> 1) THEN
    ? loJwe2.LastErrorText
    RELEASE loSbPlainText
    RELEASE loJwe
    RELEASE loJweProtHdr
    RELEASE loSbJweCompressed
    RELEASE loSbJweUncompressed
    RELEASE loJwe2
    RELEASE loSbOriginalText
    CANCEL
ENDIF

* Set the AES wrap key.
loJwe2.SetWrappingKey(0,lcAesWrappingKey,"base64url")

* Decrypt.
loSbOriginalText.Clear()
lnSuccess = loJwe2.DecryptSb(0,"utf-8",loSbOriginalText)
IF (lnSuccess <> 1) THEN
    ? loJwe2.LastErrorText
    RELEASE loSbPlainText
    RELEASE loJwe
    RELEASE loJweProtHdr
    RELEASE loSbJweCompressed
    RELEASE loSbJweUncompressed
    RELEASE loJwe2
    RELEASE loSbOriginalText
    CANCEL
ENDIF

? "original text from uncompressed JWE: "
? loSbOriginalText.GetAsString()

* ------------------------------------------------
* The output of this example is:
* (Note: Your output data will be different because the content encryption key is randomly generated.)

* eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2IiwiemlwIjoiREVGIn0.xuW-pEAIdEUFnk10m8ocursvktO8Of9ByCCAt6LgKkkOtCWCUn1kQw.zpGj-9WVni3cQxyOuZbcGA.0hzP1myua3oYpUHwCIY_3edBUREbUpLaX6wYuJduOdI.Ppc6aEO3y3B8BJ1FKMPjlA
* size of compressed JWE: 212
* eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.N4KeyC7nnSFkieJOyE24_zKeuV_m7v5UKoJb1TgV4Yc_r2RzUPNvyA.6AEdyXSCKx-iMmUJyypSLg.QpixfyrwhGpmwUDp623viik4smPav7vwPLiC2r-V-jwnSfEH3mxWu6DbrIz3mixaqATwynmEBzVPxvS9jTXpSAGCnniib4_0WoPl3r_wF5tlsKOEe--jpNso-DKd1Tp8jJxj3JkFWt3IRnUUKGj17g.sBfDwFc5fzpaI-UW8-SW4g
* size of uncompressed JWE: 303
* original text from compressed JWE: 
* Live long and prosper.
* Live long and prosper.
* Live long and prosper.
* Live long and prosper.
* 
* original text from uncompressed JWE: 
* Live long and prosper.
* Live long and prosper.
* Live long and prosper.
* Live long and prosper.
* 

RELEASE loSbPlainText
RELEASE loJwe
RELEASE loJweProtHdr
RELEASE loSbJweCompressed
RELEASE loSbJweUncompressed
RELEASE loJwe2
RELEASE loSbOriginalText