(Tcl) ClickBank Decrypt Instant Notification

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

Chilkat Tcl Extension Downloads Chilkat Tcl Extension Downloads

load ./chilkat.dll

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

# secret key from your ClickBank account
set secretKey "MY_SECRET_KEY"

set jsonStr "{\"notification\":\"BASE64_NOTIFICATION\",\"iv\":\"BASE64_IV\"}"

set json [new_CkJsonObject]

set success [CkJsonObject_Load $json $jsonStr]

# Get the encrypted notification (binary) and IV from the JSON.
set bdNotif [new_CkBinData]

set bdIv [new_CkBinData]

set success [CkBinData_AppendEncoded $bdNotif [CkJsonObject_stringOf $json "notification"] "base64"]
set success [CkBinData_AppendEncoded $bdIv [CkJsonObject_stringOf $json "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.

set crypt [new_CkCrypt2]

# Because we're using the hex string as the actual AES key, it matters whether the hex is uppercase or lowercase.
# We want lowercase.
CkCrypt2_put_EncodingMode $crypt "hex_lower"
CkCrypt2_put_HashAlgorithm $crypt "sha1"
set hexSha1 [CkCrypt2_hashStringENC $crypt $secretKey]
puts "$hexSha1"

# Treat the hex string as binary data for the AES key..
set bdKey [new_CkBinData]

CkBinData_AppendString $bdKey $hexSha1 "us-ascii"
CkBinData_RemoveChunk $bdKey 32 8

CkCrypt2_put_KeyLength $crypt 256
CkCrypt2_put_CryptAlgorithm $crypt "aes"
CkCrypt2_put_CipherMode $crypt "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..
CkCrypt2_SetEncodedIV $crypt [CkBinData_getEncoded $bdIv "base64"] "base64"
CkCrypt2_SetEncodedKey $crypt [CkBinData_getEncoded $bdKey "base64"] "base64"

CkCrypt2_DecryptBd $crypt $bdNotif
puts "Decrypted: [CkBinData_getString $bdNotif utf-8]"

delete_CkJsonObject $json
delete_CkBinData $bdNotif
delete_CkBinData $bdIv
delete_CkCrypt2 $crypt
delete_CkBinData $bdKey