(JavaScript) Demonstrate RSA Encrypt/Decrypt using BinData

See more RSA Examples

Note: This example requires Chilkat v11.0.0 or greater.

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.

var success = false;

// The RSA public key is used for encryption, and the private key for decryption.

// The public key's role is to make encryption accessible to anyone while ensuring that
// only the private key holder can decrypt the messages.
// The public key is designed to be widely distributed so anyone can use it to encrypt messages
// intended for the owner of the private key.

// Load our 2048-bit RSA public key.
var pubKey = new CkPublicKey();
// In all Chilkat methods expecting a path, you pass either absolute or relative paths.
success = pubKey.LoadFromFile("rsaKeys/myTestRsaPublic.pem");
if (success == false) {
    console.log(pubKey.LastErrorText);
    return;
}

var rsa = new CkRsa();

// Tell RSA to use the public key.
rsa.UsePublicKey(pubKey);

// RSA encryption is for small amounts of data, on the order of 200 bytes or less.
// The maximum number of bytes that can be RSA encrypted depends
// on the RSA key size and padding scheme (OAEP padding vs PKCS#1 v1.5 padding).
// For specific limits, see: RSA Encryption Maximum Number of Bytes

// Create some binary data to encrypt.
var bd = new CkBinData();
var i = 0;
for (i = 0; i <= 49; i++) {
    bd.AppendByte(i);
}

// Show the bytes to be encrypted in hex format:
console.log("To be encrypted: " + bd.GetEncoded("hex"));

// To be encrypted: 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F202122232425262728292A2B2C2D2E2F3031

// RSA encrypt the contents of the bd, replacing the contents with the RSA encrypted data.
rsa.EncryptBd(bd,false);

// Now it is encrypted.
console.log("Encrypted size = " + bd.NumBytes);
console.log(bd.GetEncoded("hex"));

// Encrypted size = 256
// 749ED9D0A8767C06C09AD9697F654F86B145F966722F9714902C4175BDBD02E68984ECF111D4D461
// EDB4A8E677D399D19CCA60F35C6DE9972F4262880FE9D77DB75915393E8E7DB80AAB5E383013FAEB
// 60C77D1E6FECC9A7C8426976416C6218FE7DA998EE063CE709E79C240F8625F4A56A0A33AFD63F7A
// BA26F2A692B42E878C53B78602C725FE63FF961A46A2B9D436E5E3D9D64AE3F1D1F5AD5F5B47FCD69
// 447306B77F2FD6D766CCAA1A110A3371586B43DF0D7FFE2220D1B305CF9371AC342F849FB0C90CD99E
// C176928D877FE1C0DE1A7CB6EB824FEC7E1DCF90EF2C6BA9F1DFD3EBFBE89C51AF074DC6AE02E544A78
// 5018C36D3D48B2EF5202AF61AC

// ------------------------------------------------------------------------------------------------------------------------
// Let's decrypt, which requires the matching private key...

// Load the matching 2048-bit RSA private key.
var privKey = new CkPrivateKey();
var password = "secret";
success = privKey.LoadAnyFormatFile("rsaKeys/myTestRsaPrivate.pem",password);
if (success == false) {
    console.log(privKey.LastErrorText);
    return;
}

// Tell the RSA object to use the private key.
rsa.UsePrivateKey(privKey);

// Decrypt
success = rsa.DecryptBd(bd,true);
if (success == false) {
    console.log(rsa.LastErrorText);
    return;
}

// Examine the contents of bd to see if it now contains the unencrypted original data.
console.log("Decrypted: " + bd.GetEncoded("hex"));

// Decrypted: 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F202122232425262728292A2B2C2D2E2F3031