Delphi ActiveX

Select the S/MIME Encryption Algorithm

Demonstrates the Chilkat Email.Pkcs7CryptAlg property, which selects the underlying symmetric encryption algorithm used when an email is sent encrypted with PKCS#7 public-key (S/MIME) encryption. Possible values are aes, aes-gcm, des, 3des, and rc2; the default is aes. This example selects AES and pairs it with a 256-bit key length.

Background: S/MIME encryption is hybrid. The message body is encrypted with a fast symmetric algorithm (the one this property chooses, such as AES) using a randomly generated one-time key; then that one-time key is itself encrypted with each recipient's public key. This gives the speed of symmetric encryption with the key-distribution convenience of public-key cryptography. Modern choices like aes are strongly preferred — older options such as des and rc2 are considered weak.

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Delphi ActiveX

var
email: TChilkatEmail;

begin
//  Demonstrates the Email.Pkcs7CryptAlg property, which selects the symmetric encryption
//  algorithm used when an email is sent encrypted with PKCS#7 (S/MIME) public-key
//  encryption.  Possible values: aes, aes-gcm, des, 3des, rc2.  The default is aes.

email := TChilkatEmail.Create(Self);
email.Subject := 'Encrypted email';
email.Body := 'This message will be S/MIME encrypted when sent.';

//  Select AES with a 256-bit key for the symmetric encryption.
email.Pkcs7CryptAlg := 'aes';
email.Pkcs7KeyLength := 256;

Memo1.Lines.Add('Pkcs7CryptAlg = ' + email.Pkcs7CryptAlg);
Memo1.Lines.Add('Pkcs7KeyLength = ' + IntToStr(email.Pkcs7KeyLength));