(Excel) ClickBank Decrypt Instant Notification

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

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

' secret key from your ClickBank account

secretKey = "MY_SECRET_KEY"


jsonStr = "{""notification"":""BASE64_NOTIFICATION"",""iv"":""BASE64_IV""}"

Dim json As Chilkat.JsonObject
Set json = Chilkat.NewJsonObject

success = json.Load(jsonStr)

' Get the encrypted notification (binary) and IV from the JSON.
Dim bdNotif As Chilkat.BinData
Set bdNotif = Chilkat.NewBinData
Dim bdIv As Chilkat.BinData
Set bdIv = Chilkat.NewBinData

success = bdNotif.AppendEncoded(json.StringOf("notification"),"base64")
success = bdIv.AppendEncoded(json.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.

Dim crypt As Chilkat.Crypt2
Set crypt = Chilkat.NewCrypt2
' Because we're using the hex string as the actual AES key, it matters whether the hex is uppercase or lowercase.
' We want lowercase.
crypt.EncodingMode = "hex_lower"
crypt.HashAlgorithm = "sha1"

hexSha1 = crypt.HashStringENC(secretKey)
Debug.Print hexSha1

' Treat the hex string as binary data for the AES key..
Dim bdKey As Chilkat.BinData
Set bdKey = Chilkat.NewBinData
success = bdKey.AppendString(hexSha1,"us-ascii")
success = bdKey.RemoveChunk(32,8)

crypt.KeyLength = 256
crypt.CryptAlgorithm = "aes"
crypt.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..
crypt.SetEncodedIV bdIv.GetEncoded("base64"),"base64"
crypt.SetEncodedKey bdKey.GetEncoded("base64"),"base64"

success = crypt.DecryptBd(bdNotif)
Debug.Print "Decrypted: "; bdNotif.GetString("utf-8")