This is an old version (2.0, March 1994) of the RSA Reference toolkit
from RSA Laboratories.  From the original documation:


> WHAT IS IT?
> 
> The name "RSAREF" means "RSA reference." RSA Laboratories intends
> RSAREF to serve as a portable, educational, reference implementation
> of cryptography.
> 
> RSAREF supports the following algorithms:
> 
>      o    RSA encryption and key generation, as defined by RSA
>           Laboratories' Public-Key Cryptography Standards (PKCS)
> 
>      o    MD2 and MD5 message digests
> 
>      o    DES (Data Encryption Standard) in cipher-block chaining mode
> 
>      o    Diffie-Hellman key agreement
> 
>      o    DESX, RSA Data Security's efficient, secure DES enhancement
> 
>      o    Triple-DES, for added security with three DES operations
> 
> Version 2.0 offers three other improvements over RSAREF 1.0: the
> ability to process messages of arbitrary length in parts; the option
> to process either binary data, or data encoded in printable ASCII;
> and support for encrypting messages for more than one recipient.
> 
> RSAREF is written in the C programming language as a library that can
> be called from an application program. A simple Internet Privacy-
> Enhanced Mail (PEM) implementation can be built directly on top of
> RSAREF, together with message parsing and formatting routines and
> certificate-management routines. RSAREF is distributed with a
> demonstration program that shows how one might build such an
> implementation.

Note that references in the documentation to US export restrictions
are no longer applicable.  Also note that the RSA patent expired in
September 2000.