MIME S/MIME Encryption Algorithm Properties

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Demonstrates the properties that control S/MIME encryption: Pkcs7CryptAlg (the symmetric content-encryption algorithm), Pkcs7KeyLength (the content-encryption key length in bits), OaepPadding (whether RSAES-OAEP key transport is used instead of RSAES-PKCS1-v1_5), and the OAEP hash settings OaepHash and OaepMgfHash. The properties are configured before calling Encrypt.

var
success: Integer;
mime: TChilkatMime;
cert: TChilkatCert;

begin
success := 0;

mime := TChilkatMime.Create(Self);
success := mime.SetBodyFromPlainText('This message will be encrypted.');
if (success = 0) then
  begin
    Memo1.Lines.Add(mime.LastErrorText);
    Exit;
  end;

//  Pkcs7CryptAlg is the symmetric content-encryption algorithm.  Supported values are aes, aes-gcm,
//  des, 3des, and rc2.  The default is aes.
mime.Pkcs7CryptAlg := 'aes';

//  Pkcs7KeyLength is the content-encryption key length in bits.  The default is 128.
mime.Pkcs7KeyLength := 256;

//  OaepPadding selects the RSA key-transport padding.  The default is 0 (RSAES-PKCS1-v1_5).
//  Set 1 to use RSAES-OAEP, in which case the OAEP hash settings apply.
mime.OaepPadding := 1;
mime.OaepHash := 'sha256';
mime.OaepMgfHash := 'sha256';

//  Load the recipient certificate (public key is sufficient for encrypting).
cert := TChilkatCert.Create(Self);
success := cert.LoadFromFile('qa_data/recipient.cer');
if (success = 0) then
  begin
    Memo1.Lines.Add(cert.LastErrorText);
    Exit;
  end;

//  Encrypt using the algorithm settings configured above.
success := mime.Encrypt(cert.ControlInterface);
if (success = 0) then
  begin
    Memo1.Lines.Add(mime.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('Encrypted with ' + mime.Pkcs7CryptAlg + ' ' + IntToStr(mime.Pkcs7KeyLength) + '-bit key.');