(Perl) Encrypt File in Chunks using AES CBC

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

Chilkat Perl Downloads Perl Module for Windows, MacOS, Linux, Alpine Linux

use chilkat();

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

$crypt = chilkat::CkCrypt2->new();

$crypt->put_CryptAlgorithm("aes");
$crypt->put_CipherMode("cbc");
$crypt->put_KeyLength(128);

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

$fileToEncrypt = "qa_data/hamlet.xml";
$facIn = chilkat::CkFileAccess->new();
$success = $facIn->OpenForRead($fileToEncrypt);
if ($success != 1) {
    print "Failed to open file that is to be encrytped." . "\r\n";
    exit;
}

$outputEncryptedFile = "qa_output/hamlet.enc";
$facOutEnc = chilkat::CkFileAccess->new();
$success = $facOutEnc->OpenForWrite($outputEncryptedFile);
if ($success != 1) {
    print "Failed to encrypted output file." . "\r\n";
    exit;
}

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

$crypt->put_FirstChunk(1);
$crypt->put_LastChunk(0);

$bd = chilkat::CkBinData->new();

$i = 0;
while ($i < $numChunks) {
    $i = $i + 1;
    if ($i == $numChunks) {
        $crypt->put_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->put_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->put_FirstChunk(1);
$crypt->put_LastChunk(1);

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

# Decrypt the encrypted output file in a single call using CBC mode:
$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:
$bSame = $facIn->FileContentsEqual($fileToEncrypt,$decryptedFile);
print "bSame = " . $bSame . "\r\n";