Xojo Plugin

AES Encrypt and Decrypt a File

_LANGUAGE_ demonstrates how to AES encrypt a file of any size, and then decrypt. Xojo Plugin

Dim success As Boolean
success = False

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

Dim crypt As New Chilkat.Crypt2

crypt.CryptAlgorithm = "aes"

// CipherMode may be "ecb" or "cbc"
crypt.CipherMode = "cbc"

// KeyLength may be 128, 192, 256
crypt.KeyLength = 256

// The padding scheme determines the contents of the bytes
// that are added to pad the result to a multiple of the
// encryption algorithm's block size.  AES has a block
// size of 16 bytes, so encrypted output is always
// a multiple of 16.
crypt.PaddingScheme = 0

// An initialization vector is required if using CBC mode.
// ECB mode does not use an IV.
// The length of the IV is equal to the algorithm's block size.
// It is NOT equal to the length of the key.
Dim ivHex As String
ivHex = "000102030405060708090A0B0C0D0E0F"
crypt.SetEncodedIV ivHex,"hex"

// The secret key must equal the size of the key.  For
// 256-bit encryption, the binary secret key is 32 bytes.
// For 128-bit encryption, the binary secret key is 16 bytes.
Dim keyHex As String
keyHex = "000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F"
crypt.SetEncodedKey keyHex,"hex"

// Encrypt a file, producing the .aes as output.
// The input file is unchanged, the output .aes contains the encrypted
// contents of the input file.

// Note: The .aes output file has no file format.  It is simply a stream
// of bytes that resembles random binary data.
Dim inFile As String
inFile = "/Users/chilkat/testData/pdf/sample.pdf"
Dim outFile As String
outFile = "/Users/chilkat/testData/p7m/sample.pdf.aes"
success = crypt.CkEncryptFile(inFile,outFile)
If (success <> True) Then
    System.DebugLog(crypt.LastErrorText)
    Return
End If

// For demonstration purposes, a different instance of the object will be used
// for decryption.
Dim decrypt As New Chilkat.Crypt2

// All settings must match to be able to decrypt:
decrypt.CryptAlgorithm = "aes"
decrypt.CipherMode = "cbc"
decrypt.KeyLength = 256
decrypt.PaddingScheme = 0
decrypt.SetEncodedIV ivHex,"hex"
decrypt.SetEncodedKey keyHex,"hex"

// Decrypt the .aes
inFile = "/Users/chilkat/testData/p7m/sample.pdf.aes"
outFile = "/Users/chilkat/testData/pdf/recovered.pdf"
success = decrypt.CkDecryptFile(inFile,outFile)
If (success = False) Then
    System.DebugLog(decrypt.LastErrorText)
    Return
End If

System.DebugLog("Success!")