New York University Faculty of Arts and Science College of Arts and Science Graduate School of Arts and Science

Computing Resources

OpenSSL (version 0.9.8)

The OpenSSL Project is a collaborative effort to develop a robust, commercial-grade, fully featured, and Open Source toolkit implementing the Secure Sockets Layer (SSL v2/v3) and Transport Layer Security (TLS v1) protocols as well as a full-strength general purpose cryptography library. The project is managed by a worldwide community of volunteers that use the Internet to communicate, plan, and develop the OpenSSL toolkit and its related documentation.

OpenSSL is based on the excellent SSLeay library developed from Eric A. Young and Tim J. Hudson. The OpenSSL toolkit is licensed under a dual-license (the OpenSSL license plus the SSLeay license) situation, which basically means that you are free to get and use it for commercial and non-commercial purposes as long as you fulfill the conditions of both licenses.

The OpenSSL toolkit includes:

libssl.a: Implementation of SSLv2, SSLv3, TLSv1 and the required code to support both SSLv2, SSLv3 and TLSv1 in the one server and client.

libcrypto.a: General encryption and X.509 v1/v3 stuff needed by SSL/TLS but not actually logically part of it. It includes routines for the following:

Ciphers libdes - EAY's libdes DES encryption package which has been floating around the net for a few years. It includes 15 'modes/variations' of DES (1, 2 and 3 key versions of ecb, cbc, cfb and ofb; pcbc and a more general form of cfb and ofb) including desx in cbc mode, a fast crypt(3), and routines to read passwords from the keyboard. RC4 encryption, RC2 encryption - 4 different modes, ecb, cbc, cfb and ofb. Blowfish encryption - 4 different modes, ecb, cbc, cfb and ofb. IDEA encryption - 4 different modes, ecb, cbc, cfb and ofb.

Digests MD5 and MD2 message digest algorithms, fast implementations, SHA (SHA-0) and SHA-1 message digest algorithms, MDC2 message digest. A DES based hash that is popular on smart cards.

Public Key RSA encryption/decryption/generation. There is no limit on the number of bits. DSA encryption/decryption/generation. There is no limit on the number of bits. Diffie-Hellman key-exchange/key generation. There is no limit on the number of bits.

X.509v3 certificates X509 encoding/decoding into/from binary ASN1 and a PEM based ASCII-binary encoding which supports encryption with a private key. Program to generate RSA and DSA certificate requests and to generate RSA and DSA certificates.

Systems The normal digital envelope routines and base64 encoding. Higher level access to ciphers and digests by name. New ciphers can be loaded at run time. The BIO io system which is a simple non-blocking IO abstraction. Current methods supported are file descriptors, sockets, socket accept, socket connect, memory buffer, buffering, SSL client/server, file pointer, encryption, digest, non-blocking testing and null.

Data structures A dynamically growing hashing system A simple stack. A Configuration loader that uses a format similar to MS .ini files.

openssl: A command line tool that can be used for: Creation of RSA, DH and DSA key parameters Creation of X.509 certificates, CSRs and CRLs Calculation of Message Digests Encryption and Decryption with Ciphers SSL/TLS Client and Server Tests Handling of S/MIME signed or encrypted mail


Various companies hold various patents for various algorithms in various locations around the world. _YOU_ are responsible for ensuring that your use of any algorithms is legal by checking if there are any patents in your country. The file contains some of the patents that we know about or are rumored to exist. This is not a definitive list.

RSA Security holds software patents on the RC5 algorithm. If you intend to use this cipher, you must contact RSA Security for licensing conditions. Their web page is

RC4 is a trademark of RSA Security, so use of this label should perhaps only be used with RSA Security's permission.

The IDEA algorithm is patented by Ascom in Austria, France, Germany, Italy, Japan, the Netherlands, Spain, Sweden, Switzerland, UK and the USA. They should be contacted if that algorithm is to be used; their web page is