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>.