Delphi DLL Requires Chilkat v11.0.0+

Demonstrate RSA Encrypt/Decrypt using BinData

See more RSA Examples

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

var
success: Boolean;
pubKey: HCkPublicKey;
rsa: HCkRsa;
bd: HCkBinData;
i: Integer;
privKey: HCkPrivateKey;
password: PWideChar;

begin
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.
pubKey := CkPublicKey_Create();
//  In all Chilkat methods expecting a path, you pass either absolute or relative paths.
success := CkPublicKey_LoadFromFile(pubKey,'rsaKeys/myTestRsaPublic.pem');
if (success = False) then
  begin
    Memo1.Lines.Add(CkPublicKey__lastErrorText(pubKey));
    Exit;
  end;

rsa := CkRsa_Create();

//  Tell RSA to use the public key.
CkRsa_UsePublicKey(rsa,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 := CkBinData_Create();
i := 0;
for i := 0 to 49 do
  begin
    CkBinData_AppendByte(bd,i);
  end;

//  Show the bytes to be encrypted in hex format:
Memo1.Lines.Add('To be encrypted: ' + CkBinData__getEncoded(bd,'hex'));

//  To be encrypted: 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F202122232425262728292A2B2C2D2E2F3031

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

//  Now it is encrypted.
Memo1.Lines.Add('Encrypted size = ' + IntToStr(CkBinData_getNumBytes(bd)));
Memo1.Lines.Add(CkBinData__getEncoded(bd,'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.
privKey := CkPrivateKey_Create();
password := 'secret';
success := CkPrivateKey_LoadAnyFormatFile(privKey,'rsaKeys/myTestRsaPrivate.pem',password);
if (success = False) then
  begin
    Memo1.Lines.Add(CkPrivateKey__lastErrorText(privKey));
    Exit;
  end;

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

//  Decrypt
success := CkRsa_DecryptBd(rsa,bd,True);
if (success = False) then
  begin
    Memo1.Lines.Add(CkRsa__lastErrorText(rsa));
    Exit;
  end;

//  Examine the contents of bd to see if it now contains the unencrypted original data.
Memo1.Lines.Add('Decrypted: ' + CkBinData__getEncoded(bd,'hex'));

//  Decrypted: 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F202122232425262728292A2B2C2D2E2F3031

CkPublicKey_Dispose(pubKey);
CkRsa_Dispose(rsa);
CkBinData_Dispose(bd);
CkPrivateKey_Dispose(privKey);