OpenSSL

Digital certificates can be easily created with the command-line OpenSSL tool or with any other tool made for that purpose.

OpenSSL is the cryptography library used for SSL communications, and is required by mod_ssl to encrypt HTTP traffic for Apache.

Some of the algorithms supported by the OpenSSL library are patented or otherwise protected and may need to be licensed for use.

If the certificate cannot be verified for trust, OpenSSL flags the certificate as invalid (but the connection can still continue).

This article goes deeper into OpenSSL, showing you how to secure the handshake against what is called a man in the middle (MITM) attack.

In the OpenSSL library, traditional socket calls are mimicked with a similar API that uses SSL context objects in place of file descriptors.

The first two parts of this series discuss creating client-side applications using OpenSSL.

Part of the problem with learning how to implement OpenSSL is the fact that the documentation is not complete.

Note that not all of the digest and ciphers here are supported, but your OpenSSL must support the cipher and digest that you want to use.

Not many tutorials on the use of OpenSSL exist either, so getting it to work in applications can be a little troublesome for beginners.

It should also be noted here that OpenSSL is not officially supported on all platforms.

Encryption is a complex topic, but a basic overview of how TLS works is needed to use the OpenSSL package.

Instead, OpenSSL creates another BIO that must be popped off of the accept BIO using BIO_pop.

Binary distributions are typically compiled and distributed by third parties, not by the OpenSSL developers.

If you will be using OpenSSL to make certificate requests and digital certificates, then a configuration file must be created.

The OpenSSL website provides downloads and documentation on this software.

Overall, creating a secure server application with OpenSSL is not difficult once you understand the basics of how it's done.

With this option set, if the server suddenly wants a new handshake, OpenSSL handles it in the background.

The OpenSSL performance was identical between the two systems.

It is now available as an installp image format; see the Resources section for download information.

Because it is not part of the SSL standard, OpenSSL does not check the certificate's name against the host name.

OpenSSL uses an abstraction library called BIO to handle communication of various kinds, including files and sockets, both secure and not.

Creating a basic server application using OpenSSL is almost identical in nature to creating a basic client application.

The source code does not have external dependencies except for standard libraries like BDB, OpenSSL, TCL, STL, glibc and expat.

Developers can find news and documentation related to OpenSSL as well as access the OpenSSL mailing lists.

Instead, OpenSSL provides a callback mechanism for obtaining the password.

A template file called openssl. cnf is available in the apps folder of the OpenSSL package.

Most of the X. 509 structures used inside of OpenSSL you will most likely never use in an application.

There are also only three lines necessary to initialize the OpenSSL library.

OpenSSL has an entire internal library devoted to digital certificates.

If this parameter is NULL, OpenSSL writes the string to a static buffer that is 256 bytes in length, and returns a pointer to that buffer.

Create a self-signed server key (server. key) and certificate (server. crt) using the OpenSSL command-line tool openssl.

All are in the openssl subdirectory, and all three will be required for developing your project.

If the certificate passed OpenSSL's internal checks, including checking for trust, then it returns X509_V_OK.

Stunnel requires that OpenSSL already be installed.

In particular, the impact of OpenSSL (and specific tools like OpenSSH) has been immense.

You can determine the list of ciphers and message digest formats supported by using openssl help, as shown here in Listing 1.

You may recall from Part 1 how I established both SSL and non-SSL communication using OpenSSL's BIO library.

The required software is OpenSSL and stunnel.

At the time of this writing, the latest version is 0. 9. 7d.

Part 1 discusses creating a basic secure client using OpenSSL, while Part 2 talks more in depth about digital certificates.

OpenSSL is a popular open-source library for TLS.

PKCS12 files can be in PEM (as created by openssl pkcs12).

So how can you implement a basic secure connection using OpenSSL?

If you haven't already done so, please read Part 1 in the series, " Overview of the API, " to learn how to set up the OpenSSL library.

It relies on a separate library such as OpenSSL or SSLeay to implement the underlying TLS or SSL protocol.

Stunnel is a program that can encrypt arbitrary TCP sessions using the OpenSSL library.

For information on how to use the OpenSSL command-line tool, look in the Resources section.

Create the server key: openssl genrsa -des3 -out server. key 1024.

You may want to consider upgrading other software such as openssl, openssh, lsof, etc at this stage.

After you've installed the OpenSSL and stunnel programs, complete these steps

OpenSSL -- the Secure Sockets Layer (SSL) security library

OpenSSL, for secure sockets layer support

To install the Open SSL code, and click