(PHP Extension) Demonstrate RSA Encrypt/Decrypt using BinData

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Demonstrates how to RSA encrypt and decrypt data contained in a Chilkat BinData object.

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<?php

include("chilkat.php");
// Use "chilkat_9_5_0.php" for versions of Chilkat < 10.0.0

// 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.
$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) {
    print $pubKey->lastErrorText() . "\n";
    exit;
}

$rsa = new CkRsa();

// Tell RSA to use the public key.
$rsa->ImportPublicKeyObj($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.
$bd = new CkBinData();
$i = 0;
for ($i = 0; $i <= 49; $i++) {
    $bd->AppendByte($i);
}

// Show the bytes to be encrypted in hex format:
print 'To be encrypted: ' . $bd->getEncoded('hex') . "\n";

// 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.
print 'Encrypted size = ' . $bd->get_NumBytes() . "\n";
print $bd->getEncoded('hex') . "\n";

// 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.
$privKey = new CkPrivateKey();
$password = 'secret';
$success = $privKey->LoadAnyFormatFile('rsaKeys/myTestRsaPrivate.pem',$password);
if ($success == false) {
    print $privKey->lastErrorText() . "\n";
    exit;
}

// Tell the RSA object to use the private key.
$rsa->ImportPrivateKeyObj($privKey);

// Decrypt
$success = $rsa->DecryptBd($bd,true);
if ($success == false) {
    print $rsa->lastErrorText() . "\n";
    exit;
}

// Examine the contents of bd to see if it now contains the unencrypted original data.
print 'Decrypted: ' . $bd->getEncoded('hex') . "\n";

// Decrypted: 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F202122232425262728292A2B2C2D2E2F3031

?>