cryptography

1. SRI KRISHNA INSTITUTE OF TECHNOLOGY
DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING
Name : Nishanth R
USN : 1KT19CS056
Branch : CSE
Subject : Cryptography
Subject Code : 18CS744
Topic : MIME

2. SRI KRISHNA INSTITUTE OF TECHNOLOGY
DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING
MIME(Multipurpose Internet Mail Extension):
 MIME is a standard which was proposed by Bell Communications in 1991 in order to expand
the limited capabilities of mail.
 Email has a simple structure.
 Email can send messages only in NVT 7-bit ASCII format.
 In short, MIME is a supplementary protocol or a add on which allows non ASCII data to be
sent through Email using SMTP.
 It allows users to exchange different kinds of data files on the internet like
audio,video,images, etc.,
 MIME is an extension to the internet email protocol.

3. SRI KRISHNA INSTITUTE OF TECHNOLOGY
DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING
 Email messages with MIME formatting are typically transmitted with standard protocols like
SMTP(Simple Mail Transfer protocol), POP(Post office Protocol),& the IMAP(Internet
Message Access Protocol).
 Although MIME was designed mainly for SMTP, its contents types are also important in other
communication protocols. For example, In HTTP protocol for the World Wide Web, servers
insert a MIME header field at the beginning of any web transmission.
Limitations of SMTP:
 SMTP has a very simple structure.
 SMTP can only send the messages in NVT 7-bit ASCII format.
 It cannot be used for languages that do not support 7-bit ASCII format such as French,
German,etc., so in order to make SMTP more broad , we use MIME.
 It cannot be used to send binary files or video or audio data.

4. SRI KRISHNA INSTITUTE OF TECHNOLOGY
DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING
MIME header:
 It is added to the original E-mail header section to define transformation.
 There are five header fields which we add on to the original header:
• MIME version - Must have the parameter value 1.0. This field indicates that the
message conforms to RFCs 2045 and 2046.
• Content-Type: Describes the data contained in the body with sufficient detail that the
receiving user agent can pick an appropriate agent or mechanism to represent the data to
the user or otherwise deal with the data in an appropriate manner.
• Content-Transfer-Encoding: Indicates the type of transformation that has been used to
represent the body of the message in a way that is acceptable for mail transport.

5. SRI KRISHNA INSTITUTE OF TECHNOLOGY
DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING
• Content-ID: Used to identify MIME entities uniquely in multiple contexts.
• Content-Description: A text description of the object with the body; this is useful when
the object is not readable (e.g., audio data).
MIME content types:
 The bulk of the MIME specification is concerned with the definition of a variety of content
types.
 There are seven different major types of content and a total of 15 subtypes. In general, a
content type declares the general type of data, and the subtype specifies a particular format for
that type of data.

6. SRI KRISHNA INSTITUTE OF TECHNOLOGY
DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING