Overview of SSL

Digital signatures and digital certificates

The following document defines and discusses digital signatures, and certificates. You are responsible for all material there, except for S/MIME certificates, e-mail encryption and signing, form signing, and object signing.

Introduction to public key cryptoraphy at netscape.com

The following brief and humorous overview of digital signatures and certificates can be used as a quick reference in addition to the above material:

"What is a digital signature?" by David Youd.

SSL protocol

SSL is a protocol which tuns on top of TCP. SSL transmits data in an encrypted form, which guarantees that even if someone intercepts the transmission, they would not be able to read it. If data is submitted via SSL protocol, then the URL address in the browser starts with https instead of http. If your machine and the machine you are connecting to both support SSL, then you can initiate a secure transmission by typing https instead of http.

SSL protocol includes "SSL handshake" -- a subprotocol for the two computers to agree on the common encryption algorithm. This part of the protocol also requires authentication of the server by the client and, optionally, of the client by the server. Authentication is done by means of certificates.

Please see Introduction to SSL at netscape.com for a detailed description of SSL. You don't need to remember the names and know the details of particular ciphers and message digest functions used in SSL protocol, such as RC2, RC4, MD5, etc. You need to know the steps of SSL protocols, in particular of sub-protocols for server and client authentication, and the purpose of each step.

Note that the restrictions on export of strong encryption products (mentioned in the article) are no longer valid. Click here for details on the new export policy. You don't need to know the details of the policy.

This page has been created and is maintained by Elena Machkasova
Comments and suggestions are welcome at emachkas@wellesley.edu

Spring Semester 2002