Hi All

We have requirement to add digial signature authrozied by CA in PDF to ensure the security of the document send in email. 

I have created Apex class and Apex page to implement this functionality. I am not sure how to attach the signature created by Crypto.sign or Crypto.signWithCertificate method in pdf document. Can anyone help me to attach certificate to PDF document?

Apex class:
public class CryptoSign {
    public static void generateCryptoSign(){
        PageReference pageRef = Page.ApexCryptoTest;
        Blob contents = pageRef.getContentAsPDF();
        Blob contentNormal = pageRef.getContentAsPDF();
        
        String algorithmName = 'RSA-SHA1';
        String key = 'PKCS12 Key';
        Blob privateKey = EncodingUtil.base64Decode(key);
        Blob signature = Crypto.sign(algorithmName, contents, privateKey);
        
        //Blob certificate = Crypto.signWithCertificate('RSA-SHA1', contents, 'Roojai_Web_Portal');
        
        Messaging.SingleEmailMessage mail = new Messaging.SingleEmailMessage();
        mail.setSubject('Test Subject');
        mail.setHtmlBody('certificate');
        List<String> toAddr = new List<String>();
        toAddr.add('test@test.com');
        mail.setToAddresses(toAddr);
        
        List<Messaging.Emailfileattachment> attachments = new List<Messaging.Emailfileattachment>();
                
        Messaging.Emailfileattachment attach = new Messaging.Emailfileattachment();
        //attach.setFileName('Test.pdf');
        //attach.setBody(signature);
        //attachments.add(attach);
        attach = new Messaging.Emailfileattachment();
        attach.setFileName('TestNormal.pdf');
        attach.setBody(contentNormal);
        attachments.add(attach);
        mail.setFileAttachments(attachments);
        
        Messaging.sendEmail(new Messaging.SingleEmailMessage[] { mail });
    }
}

Apex Page:
<apex:page >
    This is a test page
</apex:page>