Because of complex hardware and installation requirements, I didn't attempt to implement a TriStrata security server. The security server requires an NSA (National Security Agency)-certified random number generator, as well as streaming DLTs (Digital Linear Tapes) for logging audit trails. Instead, I tested administrative functions at TriStrata's labs in Redwood Shores, Calif.

I discovered that user enrollment and key recovery are handled through differing user roles. Accounts with user-agent privileges can enroll new users into the security framework, while multiple recovery agents must mutually authenticate to recover encrypted files. Using two recovery-agent accounts, I successfully recovered an encrypted file without using the original user client. I also observed the security server display and archive administrative events. Detailed records of file-recovery operations are stored and displayed on the server. In addition, the enterprise security service demonstrated the real-time encryption of network video streams--a task that can quickly tax standard cryptosystems.

Unfortunately, I was unable to test TriStrata's Web security services, since they were not complete in time for testing. According to the vendor, ActiveX controls will let Web clients and servers access the product's security services by the time the final version ships. During testing, I did verify TriStrata's claims of superior encryption performance using its file-encryption utility, but the lack of Web support prevented me from testing the proposed scalable, secure Web transactions.

Fast, Unbreakable Encryption?

TriStrata's enterprise security service revives the 80-year-old concept of one-time pad encryption using the Vernam cipher. Any encryption textbook will tell you that the only way to properly break the Vernam cipher is to steal the original encryption key. This cipher is so secure that instead of trying to break one-time pad encryption, the espionage world continues to rely on spies to steal code books from the bad guys.

While conventional symmetric key or public-key cryptography depends on mathematical algorithms that are extremely difficult to calculate in reverse (without the original encryption key), one-time pad encryption instead relies on a stream of truly random data to mask the contents of a message. TriStrata's use of the Vernam cipher, dubbed Random Key Stream (RKS), is actually quite simple. Each bit of the original message is added (XOR) to a corresponding bit in a stream of random data--an operation that can theoretically take only a few CPU cycles compared with thousands in a DES (Data Encryption Standard) operation. With this approach, TriStrata's encryption is extremely fast; imagine a zipper combining the original message and a string of random bits. Decryption is as simple as unzipping the data with the equivalent pad of random data.

In our labs, TriStrata's file-encryption utility apparently pushed the disk I/O speed limit of our workstation, a 200-MHz Pentium Pro with 128 MB of RAM and a PCI (Peripheral Component Interconnect) Ultra-SCSI disk subsystem. It encrypted a 58-MB file in 18 seconds, compared with times of more than 130 seconds using Network Associates' PGP file-encryption product (which relies on public-key cryptography for key exchange and a 128-bit CAST cipher for actual file encryption) and 107 seconds using RSA Data Security's 40-bit SecurePC product.

So is it secure? I verified the TriStrata product's speed in our labs, but did not attempt a detailed cryptanalysis. The Vernam cipher is a very simple algorithm and is theoretically unbreakable--but only if it is used correctly. The holy grail of one-time pad encryption is that the random data must be truly random and you can never reuse it. If either of these rules is broken, your data might as well be protected by a secret decoder ring from a box of cereal. Until now, most one-time pad encryption systems relied on digital tapes to distribute the massive streams of random data for encrypting each message and were limited to extremely high-security, low-bandwidth operations. The key to TriStrata's encryption technology is its ability to extract vast amounts of non-reused, shared random data from a 1-MB block of data distributed to each enrolled client.

To fulfill the need for true random data, TriStrata's Enterprise Security Server (TESS) relies on Spyrus' NSA-certified, hardware-based random number generator for all of its encryption pads. Clients are given two blocks of random data: one for authentication services and another for encryption. But the key to TriStrata's security solution is the use of limited random data (less than 2 MB are required for the complete client enrollment) to encrypt tremendous amounts of data. Each client may encrypt hundreds of terabytes over its lifetime, and random data can never be reused. In addition to the Vernam cipher's strength, an effective security system also must have some sort of key management and control system.