(Visual FoxPro) ClickBank Decrypt Instant Notification

Demonstrates how to decrypt a ClickBank instant notification. See Instant Notification Service for more information and alternative code snippets.

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

LOCAL lcSecretKey
LOCAL lcJsonStr
LOCAL loJson
LOCAL lnSuccess
LOCAL loBdNotif
LOCAL loBdIv
LOCAL loCrypt
LOCAL lcHexSha1
LOCAL loBdKey

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

* secret key from your ClickBank account
lcSecretKey = "MY_SECRET_KEY"

lcJsonStr = '{"notification":"BASE64_NOTIFICATION","iv":"BASE64_IV"}'

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.JsonObject')
loJson = CreateObject('Chilkat.JsonObject')
lnSuccess = loJson.Load(lcJsonStr)

* Get the encrypted notification (binary) and IV from the JSON.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.BinData')
loBdNotif = CreateObject('Chilkat.BinData')
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.BinData')
loBdIv = CreateObject('Chilkat.BinData')

lnSuccess = loBdNotif.AppendEncoded(loJson.StringOf("notification"),"base64")
lnSuccess = loBdIv.AppendEncoded(loJson.StringOf("iv"),"base64")

* Get an SHA1 digest (as a hex string) of the secret key.
* A SHA1 digest is 20 bytes.  Therefore the hex string is 40 chars.
* Treat each us-ascii char as a binary byte of the secret key.
* 256-bit AES needs a 256-bit key, which is 32-bytes.  Therefore
* use the 1st 32 us-ascii chars of the hex SHA1 as the AES secret key.

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Crypt2')
loCrypt = CreateObject('Chilkat.Crypt2')
* Because we're using the hex string as the actual AES key, it matters whether the hex is uppercase or lowercase.
* We want lowercase.
loCrypt.EncodingMode = "hex_lower"
loCrypt.HashAlgorithm = "sha1"
lcHexSha1 = loCrypt.HashStringENC(lcSecretKey)
? lcHexSha1

* Treat the hex string as binary data for the AES key..
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.BinData')
loBdKey = CreateObject('Chilkat.BinData')
loBdKey.AppendString(lcHexSha1,"us-ascii")
loBdKey.RemoveChunk(32,8)

loCrypt.KeyLength = 256
loCrypt.CryptAlgorithm = "aes"
loCrypt.CipherMode = "cbc"

* We can use any encoding because were just getting the binary bytes in an encoding, and then setting from the same encoding.
* We'll just use base64..
loCrypt.SetEncodedIV(loBdIv.GetEncoded("base64"),"base64")
loCrypt.SetEncodedKey(loBdKey.GetEncoded("base64"),"base64")

loCrypt.DecryptBd(loBdNotif)
? "Decrypted: " + loBdNotif.GetString("utf-8")

RELEASE loJson
RELEASE loBdNotif
RELEASE loBdIv
RELEASE loCrypt
RELEASE loBdKey