C#

Streaming Encryption by Encrypting in Chunks

See more Encryption Examples

Encrypt data in chunks. C#

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

Chilkat.Crypt2 crypt = new Chilkat.Crypt2();

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

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

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

Chilkat.StringBuilder sbEncrypted = new Chilkat.StringBuilder();

// 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;
int 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));

Debug.WriteLine(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;
string decryptedText = crypt.DecryptStringENC(sbEncrypted.GetAsString());

Debug.WriteLine(decryptedText);

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