Xbase++

AES Encrypt and Decrypt a File

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

LOCAL nSuccess
LOCAL oCrypt
LOCAL cIvHex
LOCAL cKeyHex
LOCAL cInFile
LOCAL cOutFile
LOCAL oDecrypt

nSuccess := 0

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

oCrypt := CreateObject("Chilkat.Crypt2")

oCrypt:CryptAlgorithm := "aes"

//  CipherMode may be "ecb" or "cbc"
oCrypt:CipherMode := "cbc"

//  KeyLength may be 128, 192, 256
oCrypt: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.
oCrypt: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.
cIvHex := "000102030405060708090A0B0C0D0E0F"
oCrypt:SetEncodedIV(cIvHex, "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.
cKeyHex := "000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F"
oCrypt:SetEncodedKey(cKeyHex, "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.
cInFile := "/Users/chilkat/testData/pdf/sample.pdf"
cOutFile := "/Users/chilkat/testData/p7m/sample.pdf.aes"
nSuccess := oCrypt:CkEncryptFile(cInFile, cOutFile)
IF (nSuccess != 1)
    ? oCrypt:LastErrorText
    oCrypt:destroy()
    RETURN
ENDIF

//  For demonstration purposes, a different instance of the object will be used
//  for decryption.
oDecrypt := CreateObject("Chilkat.Crypt2")

//  All settings must match to be able to decrypt:
oDecrypt:CryptAlgorithm := "aes"
oDecrypt:CipherMode := "cbc"
oDecrypt:KeyLength := 256
oDecrypt:PaddingScheme := 0
oDecrypt:SetEncodedIV(cIvHex, "hex")
oDecrypt:SetEncodedKey(cKeyHex, "hex")

//  Decrypt the .aes
cInFile := "/Users/chilkat/testData/p7m/sample.pdf.aes"
cOutFile := "/Users/chilkat/testData/pdf/recovered.pdf"
nSuccess := oDecrypt:CkDecryptFile(cInFile, cOutFile)
IF (nSuccess == 0)
    ? oDecrypt:LastErrorText
    oCrypt:destroy()
    oDecrypt:destroy()
    RETURN
ENDIF

? "Success!"

oCrypt:destroy()
oDecrypt:destroy()