Cryptography and network Security PGP and S MIME, network security, william stallings

1. Pretty Good Privacy

2. What is PGP?
• Open source software package
• Provide e-mail security
Authentication
Confidentiality
Compression
E-mail Compatibility
Segmentation &
Reassembly
Digital Signature
Symmetric Block Encryption
ZIP Algorithm
Radix-64
To accommodate long e-mail

3. PGP is widely used
• Its available free worldwide
• It is based on algorithms that have survived extensive public review and
are considered extremely secure
Public Key Encryption: RSA, DSS, Diffie-Hellman
Symmetric Encryption: CAST-128, IDEA, 3DES
Hashing: SHA-1
• It has wide range of applicability
• It was not developed by, nor it is controlled by, any governmental or
standards organization.
• PGP is now on an Internet Standard Track(RFC 3156)

4. PGP Authentication

5. PGP Confidentiality

6. PGP Confidentiality & Authentication

7. PGP General Format

8. S/MIME

9. What is S/MIME?
S/MIME (Secure/Multipurpose Internet Mail Extension) is a
security enhancement to the MIME Internet e-mail format
standard.
S/MIME provides…
Authentication.
Message Integrity. By using digital signing
Non-repudiation of origin.
Privacy and data security. By using encryption

10. MIME Header Fields
MIME Version
Content Type
Content transfer encoding
Content ID
Content Description

11. S/MIME Types
Type Subtype Description
Text Plain
Enriched
Unformatted text (ASCII or ISO 8859).
Provides greater format flexibility.
Multipart Mixed
Parallel
Alternative
Digest
The different parts are independent but are to be
transmitted together. Should be presented to the
receiver in their original order.
Differs from mixed only in that no order is defined.
The different parts are alternative versions of the
same information.
Similar to Mixed but the default type/subtype of
each part is message/rfc822.
Message rfc822
Partial
External body
The body is itself an encapsulated message that
conforms to RFC822.
Used to allow fragmentation in a transparent way to
the recipient.
Contains a pointer to an object exists else where.

12. S/MIME Types
Type Subtype Description
Image Jpeg
gif
The image is in JPEG format.
The image is in GIF format.
Video Mpeg MPEG format.
Audio Basic Single-channel 8-bit ISDN mu-law encoding at a
sample rate of 8kHz
Application Postscript
Octet-stream
Adobe Postscirpt.
General binary data consisting of 8-bit bytes.

13. S/MIME Functions
Enveloped Data
Signed Data
Clear Signe Data
Signed and Enveloped Data