Go

AES Encrypt and Decrypt a File

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

    success := false

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

    crypt := chilkat.NewCrypt2()

    crypt.SetCryptAlgorithm("aes")

    // CipherMode may be "ecb" or "cbc"
    crypt.SetCipherMode("cbc")

    // KeyLength may be 128, 192, 256
    crypt.SetKeyLength(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.SetPaddingScheme(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.
    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.
    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.
    inFile := "/Users/chilkat/testData/pdf/sample.pdf"
    outFile := "/Users/chilkat/testData/p7m/sample.pdf.aes"
    success = crypt.CkEncryptFile(inFile,outFile)
    if success != true {
        fmt.Println(crypt.LastErrorText())
        crypt.DisposeCrypt2()
        return
    }

    // For demonstration purposes, a different instance of the object will be used
    // for decryption.
    decrypt := chilkat.NewCrypt2()

    // All settings must match to be able to decrypt:
    decrypt.SetCryptAlgorithm("aes")
    decrypt.SetCipherMode("cbc")
    decrypt.SetKeyLength(256)
    decrypt.SetPaddingScheme(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 {
        fmt.Println(decrypt.LastErrorText())
        crypt.DisposeCrypt2()
        decrypt.DisposeCrypt2()
        return
    }

    fmt.Println("Success!")

    crypt.DisposeCrypt2()
    decrypt.DisposeCrypt2()