(JavaScript) Streaming Encryption by Encrypting in Chunks

Encrypt data in chunks.

Note

This example is intended for running within a Chilkat.Js embedded JavaScript engine. All Chilkat JavaScript examples require Chilkat v11.4.0 or greater.

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

var crypt = new CkCrypt2();

crypt.CryptAlgorithm = "aes";
crypt.CipherMode = "cbc";
crypt.KeyLength = 128;

crypt.SetEncodedKey("000102030405060708090A0B0C0D0E0F","hex");
crypt.SetEncodedIV("000102030405060708090A0B0C0D0E0F","hex");

crypt.EncodingMode = "hex";
var txt1 = "The quick brown fox jumped over the lazy dog.\r\n";
var txt2 = "-\r\n";
var txt3 = "Done.\r\n";

var sbEncrypted = new CkStringBuilder();

// Encrypt the 1st chunk:
// (don't worry about feeding the data to the encryptor in 
// exact multiples of the encryption algorithm's block size.
// Chilkat will buffer the data.)
crypt.FirstChunk = true;
crypt.LastChunk = false;
sbEncrypted.Append(crypt.EncryptStringENC(txt1));

// Encrypt the 2nd chunk
crypt.FirstChunk = false;
crypt.LastChunk = false;
sbEncrypted.Append(crypt.EncryptStringENC(txt2));

// Now encrypt N more chunks...
// Remember -- we're doing this in CBC mode, so each call
// to the encrypt method depends on the state from previous
// calls...
crypt.FirstChunk = false;
crypt.LastChunk = false;
var i;
for (i = 0; i <= 4; i++) {
    sbEncrypted.Append(crypt.EncryptStringENC(txt1));
    sbEncrypted.Append(crypt.EncryptStringENC(txt2));
}

// Now encrypt the last chunk:
crypt.FirstChunk = false;
crypt.LastChunk = true;
sbEncrypted.Append(crypt.EncryptStringENC(txt3));

console.log(sbEncrypted.GetAsString());

// Now decrypt in one call.
// (The data we're decrypting is both the first AND last chunk.)  
crypt.FirstChunk = true;
crypt.LastChunk = true;
var decryptedText = crypt.DecryptStringENC(sbEncrypted.GetAsString());

console.log(decryptedText);

// Note: You may decrypt in N chunks by setting the FirstChunk
// and LastChunk properties prior to calling the Decrypt* methods