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JWE using PBES2 Key Wrapping

See more JSON Web Encryption (JWE) Examples

Demonstrates how to create and decrypt a JWE that using PBES2 key wrapping.

This example demonstrates PBES2 with HMAC SHA-256 and A128KW wrapping. It is also possible to do the following by simply changing the "alg" parameter:

• PBES2 with HMAC SHA-384 and A192KW wrapping
• PBES2 with HMAC SHA-512 and A256KW wrapping

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

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Local $bSuccess = 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.

Local $sPlaintext = "Live long and prosper."

$oJwe = ObjCreate("Chilkat.Jwe")

;  First build the JWE Protected Header..
$oJweProtHdr = ObjCreate("Chilkat.JsonObject")
$oJweProtHdr.AppendString("alg","PBES2-HS256+A128KW")
$oJweProtHdr.AppendString("enc","A128GCM")

;  PBES2 requires two additional parameters:
;  1) A random salt parameter ("p2s") containing 8 or more bytes in base64url format.
;  2) An iteration count parameter ("p2c").  A minimum count of 1000 is recommended.
;     The iteration count is intended to make the PBES2 computation more expensive (time consuming)
;     to prevent brute-force attacks.
$oPrng = ObjCreate("Chilkat.Prng")
$oJweProtHdr.AppendString("p2s",$oPrng.GenRandom(16,"base64url"))
$oJweProtHdr.AppendString("p2c","1000")

ConsoleWrite("JWE Protected Header: " & $oJweProtHdr.Emit() & @CRLF)
ConsoleWrite("--" & @CRLF)

;  Don't forget to actually provide the protected header to the JWE object:
$oJwe.SetProtectedHeader($oJweProtHdr)

;  Set the PBES2 password
Local $iRecipientIndex = 0
$oJwe.SetPassword($iRecipientIndex,"top secret")

;  Encrypt and return the JWE:
Local $strJwe = $oJwe.Encrypt($sPlaintext,"utf-8")
If ($oJwe.LastMethodSuccess <> True) Then
    ConsoleWrite($oJwe.LastErrorText & @CRLF)
    Exit
EndIf

;  Show the JWE we just created:
ConsoleWrite($strJwe & @CRLF)

;  Decrypt the JWE.
$oJwe2 = ObjCreate("Chilkat.Jwe")
$bSuccess = $oJwe2.LoadJwe($strJwe)
If ($bSuccess <> True) Then
    ConsoleWrite($oJwe2.LastErrorText & @CRLF)
    Exit
EndIf

;  Set the PBES2 password
$oJwe2.SetPassword($iRecipientIndex,"top secret")

;  Decrypt.
Local $sOriginalPlaintext = $oJwe2.Decrypt(0,"utf-8")
If ($oJwe2.LastMethodSuccess <> True) Then
    ConsoleWrite($oJwe2.LastErrorText & @CRLF)
    Exit
EndIf

ConsoleWrite("original text: " & @CRLF)
ConsoleWrite($sOriginalPlaintext & @CRLF)

;  Sample output:

;  JWE Protected Header: {"alg":"PBES2-HS256+A128KW","enc":"A128GCM","p2s":"z39rTEfRy1T1Yn_D1mZRlg","p2c":"1000"}
;  --
;  eyJhbGciOiJQQkVTMi1IUzI1NitBMTI4S1ciLCJlbmMiOiJBMTI4R0NNIiwicDJzIjoiejM5clRFZlJ5MVQxWW5fRDFtWlJsZyIsInAyYyI6IjEwMDAifQ.koYt6PrFmYwcwdcT7ZcvXHA1d-Xez5h4.luGlbvEnZp-7IsBOj42Yhw.YMTcfLf8Qe4zazozGV2OAu3cUdQ8Kg.rWub47ESWkc6IqZJTvSTmg
;  original text: 
;  Live long and prosper.