Perl

Encrypt File in Chunks using AES CBC

See more Encryption Examples

Demonstrates how to use the FirstChunk/LastChunk properties to encrypt a file chunk-by-chunk. Chilkat2 Perl

use strict;
use warnings;
use Chilkat2;

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

my $crypt = Chilkat2::Crypt2->new;

$crypt->CryptAlgorithm('aes');
$crypt->CipherMode('cbc');
$crypt->KeyLength(256);

$crypt->SetEncodedKey('000102030405060708090A0B0C0D0E0F000102030405060708090A0B0C0D0E0F', 'hex');
$crypt->SetEncodedIV('000102030405060708090A0B0C0D0E0F', 'hex');

my $fileToEncrypt = 'qa_data/hamlet.xml';
my $facIn = Chilkat2::FileAccess->new;
my $success = $facIn->OpenForRead($fileToEncrypt);
if (!$success) {
    print "Failed to open file that is to be encrytped.\n";
    exit;
}

my $outputEncryptedFile = 'c:/temp/qa_output/hamlet.enc';
my $facOutEnc = Chilkat2::FileAccess->new;
$success = $facOutEnc->OpenForWrite($outputEncryptedFile);
if (!$success) {
    print "Failed to encrypted output file.\n";
    exit;
}

# Let's encrypt in 10000 byte chunks.
my $chunkSize = 10000;
my $numChunks = $facIn->GetNumBlocks($chunkSize);

$crypt->FirstChunk(1);
$crypt->LastChunk(0);

my $bd = Chilkat2::BinData->new;

my $i = 0;
while ($i < $numChunks) {
    $i = $i + 1;
    if ($i == $numChunks) {
        $crypt->LastChunk(1);
    }

    # Read the next chunk from the file.
    # The last chunk will be whatever amount remains in the file..
    $bd->Clear();
    $facIn->FileReadBd($chunkSize, $bd);

    # Encrypt.
    $crypt->EncryptBd($bd);

    # Write the encrypted chunk to the output file.
    $facOutEnc->FileWriteBd($bd, 0, 0);

    $crypt->FirstChunk(0);
}

# Make sure both FirstChunk and LastChunk are restored to 1 after
# encrypting or decrypting in chunks.  Otherwise subsequent encryptions/decryptions
# will produce unexpected results.
$crypt->FirstChunk(1);
$crypt->LastChunk(1);

$facIn->FileClose();
$facOutEnc->FileClose();

# Decrypt the encrypted output file in a single call using CBC mode:
my $decryptedFile = 'qa_output/hamlet_dec.xml';
$success = $crypt->CkDecryptFile($outputEncryptedFile, $decryptedFile);
# Assume success for the example..

# Compare the contents of the decrypted file with the original file:
my $bSame = $facIn->FileContentsEqual($fileToEncrypt, $decryptedFile);
print 'bSame = ', ($bSame ? 1 : 0), "\n";