secure MIME (S/MIME)
Secure/Multipurpose Internet Mail Extensions (S/ MIME) is a secured variant of the MIME protocol that ensures confidentiality, authenticity, and data integrity for email clients.
S/MIME dates back to 1999 and is a protocol for more secure end-to-end encryption. It works with asymmetric encryption through authentication and for digitallysigning emails using PKCS specifications, Public Key Encryption Standard (PKCS). S/MIME does not require any specific software and accepts X.509digital certificates. The newer versions of Navigator 4.0+ and Internet Explorer 4.0+ use S/MIME to encrypt emails. The current version of S/MIME is S/MIMEv3 from 1999.
Secure/Multipurpose Internet Mail Extensions was specified by the Internet Engineering Task Force( IETF) and is described in RFCs 2632 and 2633.