(Visual FoxPro) JWE Using Flattened JWE JSON Serialization

This example duplicates the example A.5 in RFC 7516 for JSON Web Encryption (JWE).

This example demonstrates using the flattened JWE JSON Serialization syntax. This example demonstrates the capability for encrypting the plaintext to a single recipient in a flattened JSON structure.

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 loJweRecipientHdr
LOCAL lnRecipientIndex
LOCAL loJweUnprotHdr
LOCAL lcAesWrappingKey
LOCAL lcStrJwe
LOCAL loJsonTemp
LOCAL loJwe2
LOCAL lcOriginalPlaintext
LOCAL loSbJwe

* 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: {"enc":"A128CBC-HS256"}
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.JsonObject')
loJweProtHdr = CreateObject('Chilkat.JsonObject')
loJweProtHdr.AppendString("enc","A128CBC-HS256")
loJwe.SetProtectedHeader(loJweProtHdr)

* We have a single recipient that uses AES Key Wrap to encrypt the CEK.
* 
*      {"alg":"A128KW","kid":"7"}

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.JsonObject')
loJweRecipientHdr = CreateObject('Chilkat.JsonObject')
loJweRecipientHdr.AppendString("alg","A128KW")
loJweRecipientHdr.AppendString("kid","7")
lnRecipientIndex = 0
loJwe.SetRecipientHeader(lnRecipientIndex,loJweRecipientHdr)

* Set the Shared Unprotected Header:  {"jku":"https://server.example.com/keys.jwks"}
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.JsonObject')
loJweUnprotHdr = CreateObject('Chilkat.JsonObject')
loJweUnprotHdr.AppendString("jku","https://server.example.com/keys.jwks")
loJwe.SetUnprotectedHeader(loJweUnprotHdr)

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

* OK.. everything has been specified.
* Now encrypt.  
* Indicate that we prefer the flattened JSON serialization.
loJwe.PreferFlattened = 1
lcStrJwe = loJwe.Encrypt(lcPlaintext,"utf-8")
IF (loJwe.LastMethodSuccess <> 1) THEN
    ? loJwe.LastErrorText
    RELEASE loJwe
    RELEASE loJweProtHdr
    RELEASE loJweRecipientHdr
    RELEASE loJweUnprotHdr
    CANCEL
ENDIF

* The JWE is produced in the most compact form possible (a single line).
* Let's load it into a JSON object and examine in a non-compact pretty-printed format:
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.JsonObject')
loJsonTemp = CreateObject('Chilkat.JsonObject')
loJsonTemp.Load(lcStrJwe)
loJsonTemp.EmitCompact = 0
? loJsonTemp.Emit()

* The JWE looks like this:
* (Note: Because of random values used in the encryption process, your encrypted results will be different.)

* 	{ 
* 	  "protected": "eyJlbmMiOiJBMTI4Q0JDLUhTMjU2In0",
* 	  "unprotected": { 
* 	    "jku": "https://server.example.com/keys.jwks"
* 	  },
* 	  "header": { 
* 	    "alg": "A128KW",
* 	    "kid": "7"
* 	  },
* 	  "encrypted_key": "FW7z9VxOvnF2ClicvUT4HTeqcdyh90C6qytfEFJsOb77FOwTfYrc3w",
* 	  "iv": "O6Ly5-eML3zTs-_fNX3D5Q",
* 	  "ciphertext": "Q8NLmeac9JhLh0CQPuG_7D9wVDb55eToCh0g5-FQ4M0",
* 	  "tag": "slzlo6-J9C7wSDF4dh_kBg"
* 	} 

* Now decrypt......................................

* First, load 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 loJweRecipientHdr
    RELEASE loJweUnprotHdr
    RELEASE loJsonTemp
    RELEASE loJwe2
    CANCEL
ENDIF

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

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

? "original text decrypted with AES key wrap key: "
? lcOriginalPlaintext

* ---------------------------------------------------------------------------------
* It should also be possible to decrypt the flattened JWE as shown in RFC 7516, Appendix A.5
* because it was produced using the same key.

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

loSbJwe.Append("{")
loSbJwe.Append('"protected":')
loSbJwe.Append('"eyJlbmMiOiJBMTI4Q0JDLUhTMjU2In0",')
loSbJwe.Append('"unprotected":')
loSbJwe.Append('{"jku":"https://server.example.com/keys.jwks"},')
loSbJwe.Append('"header":')
loSbJwe.Append('{"alg":"A128KW","kid":"7"},')
loSbJwe.Append('"encrypted_key":')
loSbJwe.Append('"6KB707dM9YTIgHtLvtgWQ8mKwboJW3of9locizkDTHzBC2IlrT1oOQ",')
loSbJwe.Append('"iv":')
loSbJwe.Append('"AxY8DCtDaGlsbGljb3RoZQ",')
loSbJwe.Append('"ciphertext":')
loSbJwe.Append('"KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY",')
loSbJwe.Append('"tag":')
loSbJwe.Append('"Mz-VPPyU4RlcuYv1IwIvzw"')
loSbJwe.Append("}")

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

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

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

? "original text decrypted from published flattened JWE: "
? lcOriginalPlaintext

* The output:

* original text decrypted with AES key wrap key: 
* Live long and prosper.
* original text decrypted from published flattened JWE: 
* Live long and prosper.

RELEASE loJwe
RELEASE loJweProtHdr
RELEASE loJweRecipientHdr
RELEASE loJweUnprotHdr
RELEASE loJsonTemp
RELEASE loJwe2
RELEASE loSbJwe