Decrypt 256-bit AES with Prepended IV

Download Chilkat Crypt ActiveX

Decrypt a 256-bit AES encrypted string (hex-encoded) such that the IV is prepended. The IV is 128-bits, which is equal to the block size of the encryption algorithm.

Dim crypt As New ChilkatCrypt2

Dim success As Long
success = crypt.UnlockComponent("Anything for 30-day trial")
If (success <> 1) Then
    MsgBox "Crypt component unlock failed"
    Exit Sub
End If

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

Dim hexKey As String
hexKey = "0000000000000000000000000000000000000000000000000000000000000000"
crypt.SetEncodedKey hexKey,"hex"

crypt.EncodingMode = "hex"
Dim encWithIV As String
encWithIV = "8F7D7B6BE90AE2027C6AB5397F674CA35ACC5FD4DE11382C7427CEE51006FDBBEBC9DD233AF62D6D30AF4C696088E905D16214FA2421BF16DF07658BD23B868D"

Dim iv As String
Dim encryptedText As String

'  
iv = Left$(encWithIV,32)
encryptedText = Mid$(encWithIV,33)

crypt.SetEncodedIV iv,"hex"

Dim decText As String
decText = crypt.DecryptStringENC(encryptedText)

Text1.Text = Text1.Text & encWithIV & vbCrLf
Text1.Refresh
Text1.Text = Text1.Text & iv & vbCrLf
Text1.Refresh
Text1.Text = Text1.Text & encryptedText & vbCrLf
Text1.Refresh
Text1.Text = Text1.Text & decText & vbCrLf
Text1.Refresh