RIPEM is a program developed by Mark Riordan and enhanced by Jeff
Thompson that enables secure Internet e-mail; it provides both
encryption and digital signatures, using RSA and DES routines
from RSAREF (see Question 174). RIPEM is compatible with
PKCS
#7 and PKCS #10 (see
Question 166) in support of S/MIME and other
PKCS-based messaging. RIPEM implements certificates, certification
hierarchies and CRLs (see Question 123 through
Question 129).
RIPEM is also PEM-compatible and provides a convenient application
programming interface which lets e-mail handlers link to RIPEM's
message-handling functions. RIPEM is available free for non-commercial
use in the U.S. and Canada.
To get RIPEM, read <ftp://ripem.msu.edu/pub/crypt/ripem/GETTING_ACCESS>.