{"id":1693,"date":"2011-01-26T15:00:22","date_gmt":"2011-01-26T13:00:22","guid":{"rendered":"http:\/\/www.limilabs.com\/blog\/?p=1693"},"modified":"2014-07-15T15:51:33","modified_gmt":"2014-07-15T13:51:33","slug":"send-encrypted-email-using-smime","status":"publish","type":"post","link":"https:\/\/www.limilabs.com\/blog\/send-encrypted-email-using-smime","title":{"rendered":"Send encrypted email using S\/MIME"},"content":{"rendered":"

In this article we’ll show how to send digitally encrypted and signed emails (S\/MIME) using Mail.dll .NET email component<\/a>.<\/p>\n

S\/MIME (Secure\/Multipurpose Internet Mail Extensions) is a standard for public key encryption and signing of MIME data.<\/p>\n

S\/MIME was originally developed by RSA Data Security Inc. Specification uses Cryptographic Message Syntax, an IETF specification that is identical in most respects with PKCS #7. <\/p>\n

S\/MIME provides the following cryptographic security services for electronic messaging applications: authentication, message integrity, non-repudiation of origin (using digital signatures), privacy and data security (using encryption<\/strong>). S\/MIME specifies the MIME type application\/pkcs7-mime (smime-type “enveloped-data”) for data enveloping (encrypting) where the whole (prepared) MIME entity to be enveloped is encrypted and packed into an object which subsequently is inserted into an application\/pkcs7-mime MIME entity.<\/p>\n

Encryption using MailBuilder<\/h2>\n
\r\n\/\/ C#\r\n\r\nMailBuilder builder = new MailBuilder();\r\nbuilder.Html = "<html><body>Encrypted and signed<\/body><\/html>";\r\nbuilder.Subject = "Encrypted and signed";\r\nbuilder.From.Add(new MailBox("email@in-the-certificate.com", "Alice"));\r\nbuilder.To.Add(new MailBox("bob@mail.com", "Bob"));\r\nbuilder.AddAttachment(@"c:\\report_2014.pdf");\r\n\r\nbuilder.SignWith(new X509Certificate2("SignCertificate.pfx", ""));\r\nbuilder.EncryptWith(new X509Certificate2("EncryptCertificate.pfx", ""));\r\nbuilder.EncryptWith(new X509Certificate2("BobsCertificate.pfx", ""));\r\n\r\nIMail email = builder.Create();\r\n\r\n<\/pre>\n
\r\n' VB.NET\r\n\r\nDim builder As New MailBuilder()\r\nbuilder.Html = "<html><body>Encrypted and signed<\/body><\/html>"\r\nbuilder.Subject = "Encrypted and signed"\r\nbuilder.From.Add(New MailBox("email@in-the-certificate.com", "Alice"))\r\nbuilder.[To].Add(New MailBox("bob@mail.com", "Bob"))\r\nbuilder.AddAttachment("c:\\report_2014.pdf")\r\n\r\nbuilder.SignWith(New X509Certificate2("SignCertificate.pfx", ""))\r\nbuilder.EncryptWith(New X509Certificate2("EncryptCertificate.pfx", ""))\r\nbuilder.EncryptWith(New X509Certificate2("BobsCertificate.pfx", ""))\r\n\r\nDim email As IMail = builder.Create()\r\n<\/pre>\n
Remember to encrypt your emails with both sender’s and receiver’s certificates<\/strong>.
\nThis way both parties are able to decrypt such emails.<\/p>\n
Encryption using fluent interface<\/h2>\n
\r\n\/\/ C# version\r\n\r\nIMail email = Mail\r\n    .Html("<html><body>Encrypted and signed<\/body><\/html>")\r\n    .Subject("Encrypted and signed")\r\n    .From(new MailBox("email@in-the-certificate.com", "Alice"))\r\n    .To(new MailBox("bob@mail.com", "Bob"))\r\n    .AddAttachment(@"c:\\report_2014.pdf")\r\n    .SignWith(new X509Certificate2("SignCertificate.pfx", ""))\r\n    .EncryptWith(new X509Certificate2("EncryptCertificate.pfx", ""))\r\n    .EncryptWith(new X509Certificate2("BobsCertificate.pfx", ""))\r\n    .Create();\r\n<\/pre>\n
\r\n' VB.NET\r\n\r\nDim email As IMail = Mail _\r\n\t.Html("<html><body>Encrypted and signed<\/body><\/html>") _\r\n\t.Subject("Encrypted and signed") _\r\n\t.From(New MailBox("email@in-the-certificate.com", "Alice")) _\r\n\t.To(New MailBox("bob@mail.com", "Bob")) _\r\n\t.AddAttachment("c:\\report_2014.pdf") _\r\n\t.SignWith(New X509Certificate2("SignCertificate.pfx", "")) _\r\n\t.EncryptWith(New X509Certificate2("EncryptCertificate.pfx", "")) _\r\n\t.EncryptWith(New X509Certificate2("BobsCertificate.pfx", "")) _\r\n\t.Create()\r\n<\/pre>\n
Common errors you may encounter<\/h2>\n