Security Email Protocol

Emails that we often use must be protected and standardized by security protocols before they can be correctly and securely sent to the recipient's mailbox. The Secure Email protocol S/MIME is used for this purpose. Now we will introduce the basic information about this protocol.

Secure Email protocol S/MIME (Secure/Multi-purpose Intemet Mail Extensions)

According to RSA, It is the secure transmission standard for e-mail. It is an IETF standard used to send security reports. Currently, most email products include internal support for S/MIME ｡

(1) layer in the TCP/IP protocol stack ｡

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Figure Security Email protocol S/MIME layers in the TCP/IP protocol stack

(2) Security Service: it uses PKI digital signature technology to support encryption of messages and attachments ｡

(3) encryption mechanism: Secure Email protocol S/MIME adopts one-way hashing algorithm, such as SHA-1 and MD5, the Certificate Format of S/MIME adopts the X.509 standard ｡

(4) Working principle: the authentication mechanism of S/MlME depends on the Certificate Authority of the hierarchical structure. certificates of all lower-level organizations and individuals are certified by the higher-level organizations, the top-level organizations (Root Certificates) authenticate each other, and the entire trust relationship is tree structure. In addition, S/MIME encrypts the letter content and signs the content for transmission as a special attachment ｡

(5) application fields: Various Security Email sending fields ｡

(6) Advantages: the Secure Email protocol is different from the traditional PEM protocol. Because it adopts the MIME Message format internally, it can not only send text, but also carry various additional documents, including international character sets, HTML, audio, voice emails, images, and other data types ｡