File Maven (tm) 3.5 Technical/Misc Information System Requirements ------------------- File Maven will run on any 8088/286/386/486/Pentium compatible PC that has 640K of conventional RAM (460K free) and DOS 3.0 or higher. File transfers work best when not run under Windows. Serial Link Null Modem Cable ---------------------------- There are basically two types of null modem cables: 3-wire and 7-wire. The 3-wire cable contains only transmit, receive, and ground lines. The 7-wire cable has four additional handshaking lines. File Maven supports both cables but users should get a 7-wire cable if possible for faster file transfers. A 7-wire cable can be used in 3-wire link mode, but the reverse is not true. Null modem cables are available in most computer supply stores. If possible, look for a 4-headed null-modem cable that can support both 9-pin and 25-pin serial ports at either end. DB25 DB9 DB9 DB25 ---- --- --- ---- 2 3 TX -- RX 2 3 3 2 RX -- TX 3 2 4 7 RTS -- CTS 8 5 <-- 7-wire only 5 8 CTS -- RTS 7 4 <-- 7-wire only 6 6 DSR -- DTR 4 20 <-- 7-wire only 7 5 SG -- SG 5 7 20 4 DTR -- DSR 6 6 <-- 7-wire only 3-wire/7-Wire Null Modem Pin Configuration Parallel Link Cable ------------------- There are basically two types of parallel link cables: 4-bit and 8-bit. The 8-bit cable contains more lines and uses an additional register on the parallel port for faster data transfer. File Maven supports both cables. An 8-bit cable can be used in 4-bit mode but the reverse is not true. The parallel link has three advantages over the serial link: 1. The 8-bit parallel link is up to 3 times faster than the 7-wire serial link at the fastest baud rate. 2. All standard parallel ports are 25-pin, so 4-headed cables are never needed. 3. There are no baud rate settings with the parallel link. DB25M DB25M ----- ----- 1 ????????????? 1 <-- 8-bit only 2 ????????????? 15 3 ????????????? 13 4 ????????????? 12 5 ????????????? 10 6 ????????????? 11 10 ????????????? 5 11 ????????????? 6 12 ????????????? 4 13 ????????????? 3 14 ????????????? 14 <-- 8-bit only 15 ????????????? 2 16 ????????????? 16 <-- 8-bit only 17 ????????????? 17 <-- 8-bit only 25 ????????????? 25 4-bit/8-bit Parallel Pin Configuration Cable Source ------------ A good place to buy cables is Computer Gate International at (408) 730-0673. They carry both serial (p/n CNL0925FF) and parallel (p/n CNL2525MM) "Laplink" style cables that work with File Maven. See their ad in the Computer Shopper or check out www.computergate.com. Ports and Interrupts -------------------- File Maven reads the serial and parallel ports addresses from a 14-byte array in your computer's BIOS data segment starting at 0040:0000. The four possible COM port addresses are contained in the first 8 bytes and the three possible LPT port addresses are contained in the next 6 bytes. File Maven uses direct polling instead of interrupt driven communications for the fastest possible connections. Therefore, there no are IRQ settings to adjust. Blowfish File Encryption ------------------------ File Maven uses Blowfish in ECB mode with a 32-bit key for file encryption. Blowfish, a variable size key block-encryption algorithm, was developed by Bruce Schneier, author of "Applied Cryptography" (Wiley), and presented in the April 1994 edition of Dr. Dobb's Journal. File Maven's implementation differs from the original specification in two areas. First, instead of initializing the s-boxes with the hexadecimal digits of pi, File Maven uses the output of a pseudo-random number generator. This eliminates the need for a separate 4k data file. The PRNG equation used is: rng(i)=rng(i-1)*134775813+1 where rng is a 32-bit variable initialized to ffffffff hex. Second, PCs with Intel CPUs store data in little endian format (least significant byte first in a multi-byte word). The original specification converts each block to big endian format before encrypting and back to little endian format before saving. Since this only slows encryption and does not change the security of the algorithm, File Maven skips the conversions. File Maven uses the Secure Hash Algorithm (SHA) to generate the session key. The SHA was developed by The National Institute of Standards and Technology (NIST), along with the National Security Agency (NSA). File Maven takes the user's pass phrase, converts it to uppercase, and runs it through the SHA. This results in a 160-bit message digest, or hash value. Because of government restrictions on the export of encryption techology, File Maven only uses the 32 most significant bits for the session key and thus would only be considered to have "casual" strength security. Programming Language -------------------- File Maven 3.5 was written using the Borland Pascal 7.01 compiler and contains over 15,000 lines of code. The low level Link functions were written with in-line assembly code. All code is the original work of the author except for the compiler's run-time library. No external libraries were used. Previous versions were marketed as shareware. Contacting the Author --------------------- For technical support or other inquiries, send a note to: Kent Briggs kbriggs@briggsoft.com Visit the Briggs Softworks web site at www.briggsoft.com for information on other shareware and freeware programs.
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