(Delphi DLL) Decrypt MIME using RSAES-OAEP with SHA256 and AES-128 content encryption

Demonstrates how to decrypt MIME what was encrypted with RSAES-OAEP with SHA256 and AES-128 content encryption.

In actuality, we don't really need to know in advance the various algorithms used to encrypt the MIME. When decrypting, the information about the algorithms required are embedded in the PCKS7 message itself, and this tells a decryptor what it should use.

Note: This example requires Chilkat v9.5.0.67 or greater.

Chilkat for Delphi Downloads Chilkat non-ActiveX DLL for Delphi Chilkat ActiveX DLL for Delphi * The examples here use the non-ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Mime, StringBuilder, PrivateKey, Cert;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
sb: HCkStringBuilder;
bCrlf: Boolean;
mime: HCkMime;
cert: HCkCert;
privKey: HCkPrivateKey;
mime2: HCkMime;

begin
// This requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// We begin with this encrypted MIME:

// Content-Type: application/x-pkcs7-mime; name="smime.p7m"; smime-type="enveloped-data"
// someHeader1: Some value 1
// someHeader2: Some value 2
// Content-Disposition: attachment; filename="smime.p7m"
// Content-Transfer-Encoding: base64
// 
// MIIDvAYJKoZIhvcNAQcDoIIDrTCCA6kCAQAxggGgMIIBnAIBADB1MGgxCzAJBgNVBAYTAlVTMQsw
// CQYDVQQIDAJJTDEQMA4GA1UEBwwHV2hlYXRvbjEhMB8GA1UECgwYSW50ZXJuZXQgV2lkZ2l0cyBQ
// dHkgTHRkMRcwFQYDVQQDDA5DaGlsa2F0V2lkZ2V0cwIJAMRwugDmvniwMBwGCSqGSIb3DQEBBzAP
// oA0wCwYJYIZIAWUDBAIBBIIBAFaUL1ga1bOrdqYKcMm+FHUacBvzfBxk0fnPA0AMBdN8BvTWT3CN
// YuqBhjOGyq0FpYD9pVZybUuFMCVsVyIW2O62HnsOK58YaPEUUcdH2sI+yjqX9UAn0P0nVDSsVdeK
// W8x9kMfZg+3UP+y1q+lu7VRJO3f2C9oLQpTkc4VW4n7UOcUI0waykLCjCTL8lFDb7/J3GeuMKyhH
// 5riNz50kpbzqn7m2Ks9yA+QmcTdXclclGFr2vwEUFzSdT2pxh/vaUrogCxkYWbQ2eV7vZg6O4kV0
// aqHBqySkPTAzHKiHH8K8GVdlTuJ8350CpICa4T8w7/Ht5I7dyOPPKy4C+rVtrvcwggH+BgkqhkiG
// 9w0BBwEwHQYJYIZIAWUDBAECBBDTC2WNBN+z2I47/4Feu9YqgIIB0MZvl3nC/q/Wzil6HtfQTr12
// Q5moHY+ORzAa1P9XvX2ZUFhW530mV395mQw/A4o4ekmX9eRPEZquYzZPLT8hNeZIuNdhpcSQUmad
// rKnKkR0wKJ3jJ3LhOIohVBQSYs8kVDZKq6lJBIznlsurFelZoNEhyRschhteDZx5rb7fCe8c2+/O
// DHxaqaHCAzm/Bd7kcg6FFfuTZy3tu0PgP5IsXN4OFA3kkvwjAs4XsVS8jdIcmDNBkYieE8WmJOIm
// Mz7mh/CHWLgWfGKa0Dkb9RcbFgLwYNT3GzuXFw9XPbKkEZjEAtJajWbN6P0WQl96YYd9qZxUpGxZ
// zjTHEYzViUdUXolfpLufttrRXyxN1RFWhNFMFbv66xYqklMSgpdM/Mbk+EuvX6eXayDPvDBpfYMw
// NoRAzv1Ony2c0ez9rBemJICicxAzpuvHbRxdjYs63Dnv+TYgpBK12AxWWpPIjXvw0WQKgTC3Tg8s
// EnuGhpENqso/clJBEBSn4+2WhYtYbdI5sVme67lvqQl1Xxy3r18SWaQbyDOwgYi1E+54lMDOxMy0
// y0FPHk5pP45DnXWj+XORPp5LhuZr5mf62YOXSSUwR5P0cXy4Rc+pN5lhRQPCf5z2

sb := CkStringBuilder_Create();
bCrlf := True;
CkStringBuilder_AppendLine(sb,'Content-Type: application/x-pkcs7-mime; name="smime.p7m"; smime-type="enveloped-data"',bCrlf);
CkStringBuilder_AppendLine(sb,'someHeader1: Some value 1',bCrlf);
CkStringBuilder_AppendLine(sb,'someHeader2: Some value 2',bCrlf);
CkStringBuilder_AppendLine(sb,'Content-Disposition: attachment; filename="smime.p7m"',bCrlf);
CkStringBuilder_AppendLine(sb,'Content-Transfer-Encoding: base64',bCrlf);
CkStringBuilder_AppendLine(sb,'',bCrlf);
CkStringBuilder_AppendLine(sb,'MIIDvAYJKoZIhvcNAQcDoIIDrTCCA6kCAQAxggGgMIIBnAIBADB1MGgxCzAJBgNVBAYTAlVTMQsw',bCrlf);
CkStringBuilder_AppendLine(sb,'CQYDVQQIDAJJTDEQMA4GA1UEBwwHV2hlYXRvbjEhMB8GA1UECgwYSW50ZXJuZXQgV2lkZ2l0cyBQ',bCrlf);
CkStringBuilder_AppendLine(sb,'dHkgTHRkMRcwFQYDVQQDDA5DaGlsa2F0V2lkZ2V0cwIJAMRwugDmvniwMBwGCSqGSIb3DQEBBzAP',bCrlf);
CkStringBuilder_AppendLine(sb,'oA0wCwYJYIZIAWUDBAIBBIIBAFaUL1ga1bOrdqYKcMm+FHUacBvzfBxk0fnPA0AMBdN8BvTWT3CN',bCrlf);
CkStringBuilder_AppendLine(sb,'YuqBhjOGyq0FpYD9pVZybUuFMCVsVyIW2O62HnsOK58YaPEUUcdH2sI+yjqX9UAn0P0nVDSsVdeK',bCrlf);
CkStringBuilder_AppendLine(sb,'W8x9kMfZg+3UP+y1q+lu7VRJO3f2C9oLQpTkc4VW4n7UOcUI0waykLCjCTL8lFDb7/J3GeuMKyhH',bCrlf);
CkStringBuilder_AppendLine(sb,'5riNz50kpbzqn7m2Ks9yA+QmcTdXclclGFr2vwEUFzSdT2pxh/vaUrogCxkYWbQ2eV7vZg6O4kV0',bCrlf);
CkStringBuilder_AppendLine(sb,'aqHBqySkPTAzHKiHH8K8GVdlTuJ8350CpICa4T8w7/Ht5I7dyOPPKy4C+rVtrvcwggH+BgkqhkiG',bCrlf);
CkStringBuilder_AppendLine(sb,'9w0BBwEwHQYJYIZIAWUDBAECBBDTC2WNBN+z2I47/4Feu9YqgIIB0MZvl3nC/q/Wzil6HtfQTr12',bCrlf);
CkStringBuilder_AppendLine(sb,'Q5moHY+ORzAa1P9XvX2ZUFhW530mV395mQw/A4o4ekmX9eRPEZquYzZPLT8hNeZIuNdhpcSQUmad',bCrlf);
CkStringBuilder_AppendLine(sb,'rKnKkR0wKJ3jJ3LhOIohVBQSYs8kVDZKq6lJBIznlsurFelZoNEhyRschhteDZx5rb7fCe8c2+/O',bCrlf);
CkStringBuilder_AppendLine(sb,'DHxaqaHCAzm/Bd7kcg6FFfuTZy3tu0PgP5IsXN4OFA3kkvwjAs4XsVS8jdIcmDNBkYieE8WmJOIm',bCrlf);
CkStringBuilder_AppendLine(sb,'Mz7mh/CHWLgWfGKa0Dkb9RcbFgLwYNT3GzuXFw9XPbKkEZjEAtJajWbN6P0WQl96YYd9qZxUpGxZ',bCrlf);
CkStringBuilder_AppendLine(sb,'zjTHEYzViUdUXolfpLufttrRXyxN1RFWhNFMFbv66xYqklMSgpdM/Mbk+EuvX6eXayDPvDBpfYMw',bCrlf);
CkStringBuilder_AppendLine(sb,'NoRAzv1Ony2c0ez9rBemJICicxAzpuvHbRxdjYs63Dnv+TYgpBK12AxWWpPIjXvw0WQKgTC3Tg8s',bCrlf);
CkStringBuilder_AppendLine(sb,'EnuGhpENqso/clJBEBSn4+2WhYtYbdI5sVme67lvqQl1Xxy3r18SWaQbyDOwgYi1E+54lMDOxMy0',bCrlf);
CkStringBuilder_AppendLine(sb,'y0FPHk5pP45DnXWj+XORPp5LhuZr5mf62YOXSSUwR5P0cXy4Rc+pN5lhRQPCf5z2',bCrlf);

// Load the encrypted MIME into the MIME object.
mime := CkMime_Create();
CkMime_LoadMimeSb(mime,sb);

// Provide the required cert + private key from a PFX (.pfx/.p12) file.
success := CkMime_AddPfxSourceFile(mime,'qa_data/rsaes-oaep/cert_plus_privatekey.pfx','PFX_PASSWORD');
if (success <> True) then
  begin
    Memo1.Lines.Add(CkMime__lastErrorText(mime));
    Exit;
  end;

// Decrypt.
success := CkMime_Decrypt(mime);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkMime__lastErrorText(mime));
    Exit;
  end;

// Examine the decrypted MIME.
Memo1.Lines.Add(CkMime__getMime(mime));
Memo1.Lines.Add('Decrypt test 1 succeeded.');

// -----------------------------------------------------------
// Now let's decrypt another way..
// We have the same cert and private key in PEM files..

cert := CkCert_Create();
success := CkCert_LoadFromFile(cert,'qa_data/rsaes-oaep/cert.pem');

privKey := CkPrivateKey_Create();
success := CkPrivateKey_LoadPemFile(privKey,'qa_data/rsaes-oaep/privatekey.pem');

// Decrypt using the cert + private key
mime2 := CkMime_Create();
CkMime_LoadMimeSb(mime2,sb);

success := CkMime_Decrypt2(mime2,cert,privKey);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkMime__lastErrorText(mime2));
    Exit;
  end;

// Examine the decrypted MIME.
Memo1.Lines.Add(CkMime__getMime(mime2));
Memo1.Lines.Add('Decrypt test 2 succeeded.');

CkStringBuilder_Dispose(sb);
CkMime_Dispose(mime);
CkCert_Dispose(cert);
CkPrivateKey_Dispose(privKey);
CkMime_Dispose(mime2);

end;