Visual FoxPro

JWE using AES Key Wrap and AES_128_CBC_HMAC_SHA_256

See more JSON Web Encryption (JWE) Examples

This example duplicates the example A.3 in RFC 7516 for JSON Web Encryption (JWE).

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

Visual FoxPro

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

lnSuccess = 0

* 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."

loJwe = CreateObject('Chilkat.Jwe')

* First build the JWE Protected Header: {"alg":"A128KW","enc":"A128CBC-HS256"}
loJweProtHdr = CreateObject('Chilkat.JsonObject')
loJweProtHdr.AppendString("alg","A128KW")
loJweProtHdr.AppendString("enc","A128CBC-HS256")
loJwe.SetProtectedHeader(loJweProtHdr)

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

* The example A.3 in RFC 7516 uses the following 128-bit AES key,
* specified in JWK (JSON Web Key) format:
*      {"kty":"oct",
*       "k":"GawgguFyGrWKav7AX4VKUg"
*      }
* This is just a way of saying: The key type ("kty") is 
* a bunch of octets ("k") in base64url encoding.
* We can simply set the AES wrapping key like this:
lcAesWrappingKey = "GawgguFyGrWKav7AX4VKUg"
loJwe.SetWrappingKey(0,lcAesWrappingKey,"base64url")

* 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 that was just produced.
* 1) Load the JWE.
* 2) Set the AES wrapping key.
* 3) Decrypt.
loJwe2 = CreateObject('Chilkat.Jwe')
lnSuccess = loJwe2.LoadJwe(lcStrJwe)
IF (lnSuccess <> 1) THEN
    ? loJwe2.LastErrorText
    RELEASE loJwe
    RELEASE loJweProtHdr
    RELEASE loJwe2
    CANCEL
ENDIF

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

* 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

* ---------------------------------------------------------------------------------
* It should also be possible to decrypt the JWE as shown in RFC 7516, Appendix A.3.7
* because it was produced using the same AES Wrap key.

loSbJwe = CreateObject('Chilkat.StringBuilder')
loSbJwe.Append("eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.")
loSbJwe.Append("6KB707dM9YTIgHtLvtgWQ8mKwboJW3of9locizkDTHzBC2IlrT1oOQ.")
loSbJwe.Append("AxY8DCtDaGlsbGljb3RoZQ.")
loSbJwe.Append("KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY.")
loSbJwe.Append("U0m_YmjN04DJvceFICbCVQ")

lnSuccess = loJwe2.LoadJweSb(loSbJwe)
IF (lnSuccess <> 1) THEN
    ? loJwe2.LastErrorText
    RELEASE loJwe
    RELEASE loJweProtHdr
    RELEASE loJwe2
    RELEASE loSbJwe
    CANCEL
ENDIF

loJwe2.SetWrappingKey(0,lcAesWrappingKey,"base64url")

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

? lcOriginalPlaintext

RELEASE loJwe
RELEASE loJweProtHdr
RELEASE loJwe2
RELEASE loSbJwe