C#

Compress and Encrypt a Large File (Low and Constant Memory Footprint)

See more Compression Examples

Demonstrates how to compress and encrypt a large file such that the memory footprint remains low and constant.

Note: This example requires Chilkat v9.5.0.99 or greater.

C#

bool success = false;

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

Chilkat.Compression compress = new Chilkat.Compression();
compress.Algorithm = "deflate";

// Set encryption params.
// The possible values are the same as for the corresponding properties in the Chilkat Crypt2 class/object.
// The encoded IV and Key must be specified as hex.
Chilkat.JsonObject json = new Chilkat.JsonObject();
json.UpdateString("cryptAlgorithm","aes");
json.UpdateString("cipherMode","cbc");
json.UpdateInt("keyLength",128);
json.UpdateInt("paddingScheme",0);
json.UpdateString("encodedIV","000102030405060708090A0B0C0D0E0F");
json.UpdateString("encodedKey","000102030405060708090A0B0C0D0E0F");

// Do file-to-file compression+encryption in a single call.
string inPath = "qa_data/largeFile.dat";
string outPath = "c:/temp/qa_output/compressed_encrypted.dat";
success = compress.CompressEncryptFile(json,inPath,outPath);
if (success == false) {
    Debug.WriteLine(compress.LastErrorText);
    return;
}

// We can do file-to-file decrypt/decompress like this:
string inPath2 = outPath;
string outPath2 = "c:/temp/qa_output/restored.dat";
success = compress.DecryptDecompressFile(json,inPath2,outPath2);
if (success == false) {
    Debug.WriteLine(compress.LastErrorText);
    return;
}

// Note: The above decrypt + decompress is the equivalent of doing the same in these two steps:
Chilkat.Crypt2 crypt = new Chilkat.Crypt2();
crypt.CryptAlgorithm = "aes";
crypt.CipherMode = "cbc";
crypt.KeyLength = 128;
crypt.PaddingScheme = 0;
crypt.SetEncodedIV("000102030405060708090A0B0C0D0E0F","hex");
crypt.SetEncodedKey("000102030405060708090A0B0C0D0E0F","hex");

string decryptedPath = "c:/temp/qa_output/decrypted.dat";
success = crypt.CkDecryptFile(inPath2,decryptedPath);
if (success == false) {
    Debug.WriteLine(crypt.LastErrorText);
    return;
}

string outPath3 = "c:/temp/qa_output/restored_in_two_steps.dat";
success = compress.DecompressFile(decryptedPath,outPath3);
if (success == false) {
    Debug.WriteLine(compress.LastErrorText);
    return;
}

Debug.WriteLine("Success.");