SignatureHashAlgorithm Property

This property specifies the hash algorithm for email digital signature. SHA256 is recommended.

Data Type: Long

Set the property to one of the following values:

Value	Meaning
0	RSA\SHA1(Default)
1	RSA\SHA256
2	RSA\SHA384
3	RSA\SHA512
4	RSA\MD5

Remarks

Digital signature is always signed by sender certificate. The certificate used to sign email content MUST have the public/private key pair. First of all, the user MUST get a digital certificate for personal email protection from third-party certificate authorities such as www.verisign.com. After the certificate is installed on the machine, it can be viewed by "Control Pannel" -> "Internet Options" -> "Content" -> "Certificates" -> "Personal". When you view the certificate, please note there is a line "You have a private key that corresponds to this certificate" in the certificate view, that means you are able to use this certificate to sign email content. If this line doesn't appear, that means you are unable to sign the email content by this certificate. To sign email content with EASendMail, the certificate with private key is required to be imported to Mail.SignerCert properly.

EASendMail uses built-in Certificate and CertificateCollection object to sign and encrypt email.

Example

[Visual Basic, Visual C++, Delphi] The following example demonstrates how to load certificate to encrypt email with EASendMail SMTP Component. To get the full samples of EASendMail, please refer to Samples section.

[VB6, VBA - Sign and Encrypt Email]

Const ConnectNormal = 0
Const ConnectSSLAuto = 1
Const ConnectSTARTTLS = 2
Const ConnectDirectSSL = 3
Const ConnectTryTLS = 4

Const CRYPT_MACHINE_KEYSET = 32 
Const CRYPT_USER_KEYSET = 4096 
Const CERT_SYSTEM_STORE_CURRENT_USER = 65536 
Const CERT_SYSTEM_STORE_LOCAL_MACHINE = 131072 
Const CERT_STORE_PROV_LDAP_STORE = 16

Private Sub btnSignEncryptEmail_Click() 

    Dim oSmtp As New EASendMailObjLib.Mail 
    oSmtp.LicenseCode = "TryIt" 
    
    ' Your SMTP server address
    oSmtp.ServerAddr = "smtp.emailarchitect.net" 

    ' User and password for ESMTP authentication
    oSmtp.UserName = "test@emailarchitect.net" 
    oSmtp.Password = "testpassword" 

    ' If server supports SSL/TLS connection, SSL/TLS is used automatically.
    oSmtp.ConnectType = ConnectTryTLS

    ' Set your sender email address
    oSmtp.FromAddr = "test@emailarchitect.net" 

    ' Add recipient email address
    oSmtp.AddRecipientEx "support@emailarchitect.net", 0 

    ' Set email subject
    oSmtp.Subject = "test encrypted email from VB 6.0 project" 

    ' Set email body
    oSmtp.BodyText = "this is a test encrypted email sent from VB 6.0 project" 

    ' Add digital signature
    If Not oSmtp.SignerCert.FindSubject("test@emailarchitect.net", _ 
        CERT_SYSTEM_STORE_CURRENT_USER, "my") Then 
        MsgBox oSmtp.SignerCert.GetLastError() 
        Exit Sub 
    End If 

    If Not oSmtp.SignerCert.HasPrivateKey Then 
        MsgBox "Signer certificate has not private key, " & _ 
                " this certificate can not be used to sign email!" 
        Exit Sub 
    End If 

    ' Find the encrypting certificate for every recipients
    Dim oEncryptCert As New EASendMailObjLib.Certificate 
    If Not oEncryptCert.FindSubject("support@emailarchitect.net", _ 
                            CERT_SYSTEM_STORE_CURRENT_USER, "AddressBook") Then 
        If Not oEncryptCert.FindSubject("support@emailarchitect.net", _ 
                                        CERT_SYSTEM_STORE_CURRENT_USER, "my") Then 
            MsgBox oEncryptCert.GetLastError() 
            Exit Sub 
        End If 
    End If 

    ' Add encrypting certificate
    oSmtp.RecipientsCerts.Add oEncryptCert 

    MsgBox "start to send email ..." 

    If oSmtp.SendMail() = 0 Then 
        MsgBox "email was sent successfully!" 
    Else 
        MsgBox "failed to send email with the following error:" & oSmtp.GetLastErrDescription() 
    End If 

End Sub 


[VC++- Sign and Encrypt Email]

#include "stdafx.h"
#include <tchar.h>
#include <Windows.h>

#include "EASendMailObj.tlh"
using namespace EASendMailObjLib;

const int ConnectNormal = 0;
const int ConnectSSLAuto = 1;
const int ConnectSTARTTLS = 2;
const int ConnectDirectSSL = 3;
const int ConnectTryTLS = 4;

int _tmain(int argc, _TCHAR* argv[]) 
{ 
    ::CoInitialize(NULL); 

    IMailPtr oSmtp = NULL; 
    oSmtp.CreateInstance(__uuidof(EASendMailObjLib::Mail)); 
    oSmtp->LicenseCode = _T("TryIt"); 

    // Your SMTP server address
    oSmtp->ServerAddr = _T("smtp.emailarchitect.net"); 

    // User and password for ESMTP authentication
    oSmtp->UserName = _T("test@emailarchitect.net"); 
    oSmtp->Password = _T("testpassword"); 

    // If server supports SSL/TLS connection, SSL/TLS is used automatically.
    oSmtp->ConnectType = ConnectTryTLS;

    // Set your sender email address
    oSmtp->FromAddr = _T("test@emailarchitect.net"); 

    // Add recipient email address
    oSmtp->AddRecipientEx(_T("support@emailarchitect.net"), 0); 

    // Set email subject
    oSmtp->Subject = _T("Encrypted email from Visual C++ (S/MIME)"); 

    // Set email body
    oSmtp->BodyText = _T("this is a test encrypted email sent from Visual C++"); 

    //add signer digital signature
    if(oSmtp->SignerCert->FindSubject(_T("test@emailarchitect.net"), 
        CERT_SYSTEM_STORE_CURRENT_USER , _T("my")) == VARIANT_FALSE) 
    { 
        _tprintf(_T("Error with signer certificate; %s\r\n"), 
            (const TCHAR*)oSmtp->SignerCert->GetLastError()); 
        return 0; 
    } 

    if(oSmtp->SignerCert->HasPrivateKey == VARIANT_FALSE) 
    { 
        _tprintf(_T("certificate does not have a private key, it can not sign email.\r\n")); 
        return 0; 
    } 

    // Find the encrypting certificate for every recipients
    ICertificatePtr oCert = NULL; 
    oCert.CreateInstance(__uuidof(EASendMailObjLib::Certificate)); 
    if(oCert->FindSubject(_T("support@emailarchitect.net"), 
            CERT_SYSTEM_STORE_CURRENT_USER, _T("AddressBook")) == VARIANT_FALSE) 
    { 
        if(oCert->FindSubject(_T("support@emailarchitect.net"), 
                CERT_SYSTEM_STORE_CURRENT_USER, _T("my")) == VARIANT_FALSE) 
        { 
            _tprintf(_T("Encrypting certificate not found; %s\r\n"), 
                    (const TCHAR*)oCert->GetLastError()); 
            oCert.Release(); 
            return 0; 
        } 
    } 

    // Add encrypting certificate
    oSmtp->RecipientsCerts->Add(oCert); 
    oCert.Release(); 

    _tprintf(_T("Start to send email ...\r\n")); 

    if(oSmtp->SendMail() == 0) 
    { 
        _tprintf(_T("email was sent successfully!\r\n")); 
    } 
    else 
    { 
        _tprintf(_T("failed to send email with the following error: %s\r\n"), 
            (const TCHAR*)oSmtp->GetLastErrDescription()); 
    } 

    return 0; 
} 


[Delphi - Sign and Encrypt Email]
Unit Unit1; 

Interface 

Uses 
    Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, 
    Dialogs, StdCtrls, EASendMailObjLib_TLB; // add EASendMail Unit 

Type 
    TForm1 = Class(TForm) 
    Button1: TButton; 
    Procedure Button1Click(Sender: TObject); 
    private 
    { Private declarations } 
    public 
    { Public declarations } 
    End; 

Const 
    ConnectNormal = 0;
    ConnectSSLAuto = 1;
    ConnectSTARTTLS = 2;
    ConnectDirectSSL = 3;
    ConnectTryTLS = 4;

    CRYPT_MACHINE_KEYSET = 32; 
    CRYPT_USER_KEYSET = 4096; 
    CERT_SYSTEM_STORE_CURRENT_USER = 65536; 
    CERT_SYSTEM_STORE_LOCAL_MACHINE = 131072; 
    CERT_STORE_PROV_LDAP_STORE = 16;

Var 
    Form1: TForm1; 

Implementation 

{$R *.dfm} 

Procedure TForm1.Button1Click(Sender: TObject); 
Var 
    oSmtp : TMail; 
    oEncryptCert : TCertificate; 
Begin 
    oSmtp := TMail.Create(Application); 
    oSmtp.LicenseCode := 'TryIt'; 

    // Your SMTP server address
    oSmtp.ServerAddr := 'smtp.emailarchitect.net'; 

    // User and password for ESMTP authentication
    oSmtp.UserName := 'test@emailarchitect.net'; 
    oSmtp.Password := 'testpassword'; 

    // If server supports SSL/TLS connection, SSL/TLS is used automatically.
    oSmtp.ConnectType := ConnectTryTLS;

    // Set your sender email address
    oSmtp.FromAddr := 'test@emailarchitect.net'; 

    // Add recipient email address
    oSmtp.AddRecipientEx('support@emailarchitect.net', 0); 

    // Set email subject
    oSmtp.Subject := 'test encrypted email from Delphi with digital signature'; 

    // Set body text
    oSmtp.BodyText := 'this is a test encrypted email sent from Delphi with digital signature'; 

    // Add digital signature
    If Not oSmtp.SignerCert.FindSubject('test@emailarchitect.net', 
    CERT_SYSTEM_STORE_CURRENT_USER, 'my') Then 
    Begin 
        ShowMessage(oSmtp.SignerCert.GetLastError()); 
        exit; 
    End; 

    If Not oSmtp.SignerCert.HasCertificate Then 
    Begin 
        ShowMessage('Signer certificate has no private key, ' + 
        'this certificate can not be used to sign email'); 
    End; 

    // Find the encrypting certificate for every recipients
    oEncryptCert := TCertificate.Create(Application); 
    If Not oEncryptCert.FindSubject('support@emailarchitect.net', 
    CERT_SYSTEM_STORE_CURRENT_USER, 'AddressBook') Then 
    If Not oEncryptCert.FindSubject('support@emailarchitect.net', 
    CERT_SYSTEM_STORE_CURRENT_USER, 'my') Then 
    Begin 
        ShowMessage(oEncryptCert.GetLastError()); 
        exit; 
    End; 

    // Add encrypting certificate
    oSmtp.RecipientsCerts.Add(oEncryptCert.DefaultInterface); 

    ShowMessage('start to send email ...'); 

    If oSmtp.SendMail() = 0 Then 
    ShowMessage('email was sent successfully!') 
    Else 
    ShowMessage('failed to send email with the following error: ' 
    + oSmtp.GetLastErrDescription()); 

End; 

End. 


[VB6, VBA - Find Certificate in Active Directory by LDAP]
Const ConnectNormal = 0
Const ConnectSSLAuto = 1
Const ConnectSTARTTLS = 2
Const ConnectDirectSSL = 3
Const ConnectTryTLS = 4

Const CRYPT_MACHINE_KEYSET = 32 
Const CRYPT_USER_KEYSET = 4096 
Const CERT_SYSTEM_STORE_CURRENT_USER = 65536 
Const CERT_SYSTEM_STORE_LOCAL_MACHINE = 131072 
Const CERT_STORE_PROV_LDAP_STORE = 16

Private Sub btnEncryptEmail_Click() 

    Dim oSmtp As New EASendMailObjLib.Mail 
    oSmtp.LicenseCode = "TryIt" 

    ' Your SMTP server address
    oSmtp.ServerAddr = "smtp.emailarchitect.net" 

    ' User and password for ESMTP authentication
    oSmtp.UserName = "test@emailarchitect.net" 
    oSmtp.Password = "testpassword" 

    ' If server supports SSL/TLS connection, SSL/TLS is used automatically.
    oSmtp.ConnectType = ConnectTryTLS

    ' Set your sender email address
    oSmtp.FromAddr = "test@emailarchitect.net" 

    ' Add recipient email address
    oSmtp.AddRecipientEx "Support <support@emailarchitect.net>", 0 

    ' Set email subject
    oSmtp.Subject = "test encrypted email from VB 6.0 project" 

    ' Set email body
    oSmtp.BodyText = "this is a test encrypted email sent from VB 6.0 project" 

    ' Add digital signature
    If Not oSmtp.SignerCert.FindSubject("test@emailarchitect.net", _ 
        CERT_SYSTEM_STORE_CURRENT_USER, "my") Then 
        MsgBox oSmtp.SignerCert.GetLastError() 
        Exit Sub 
    End If 

    If Not oSmtp.SignerCert.HasPrivateKey Then 
        MsgBox "Signer certificate has not private key, " & _ 
                " this certificate can not be used to sign email!" 
        Exit Sub 
    End If 

    ' Please change the ldap path as your environment.
    Dim oEncryptCert As New EASendMailObjLib.Certificate 
    If Not oEncryptCert.FindSubject("support@emailarchitect.net", _ 
        CERT_STORE_PROV_LDAP_STORE, "ldap:///CN=Support,CN=USERS,DC=my,DC=server?userCertificate") Then 
            MsgBox oEncryptCert.GetLastError() 
            Exit Sub 
    End If 

    ' Add encrypting certificate
    oSmtp.RecipientsCerts.Add oEncryptCert 

    MsgBox "start to send email ..." 

    If oSmtp.SendMail() = 0 Then 
        MsgBox "email was sent successfully!" 
    Else 
        MsgBox "failed to send email with the following error:" & oSmtp.GetLastErrDescription() 
    End If 

End Sub