The PC DOC program WINCRACK "cracks" file enciphered by the utility WINCRYPT. WINCRYPT is described in "WinCrypt Protects Your Data" by Jeff Prosise starting on page 361 of the July 1994 issue of PC Magazine (Volume 13 Number 13). Essentially, WINCRYPT implements a Vigenere cipher (using exclusive-or instead of modular addition) with a 512 byte key. Thus, every 512-th byte of enciphered text is enciphered in the same Caesar alphabet. For each of the 512 Caesar ciphers, WINCRACK finds the enciphered value of the most frequent plaintext character. Given a very frequent plaintext character (e.g., space in a text file), this allows most of the Caesar alphabets to be recovered; most of the plaintext is then recovered. For example, using the attached files, "WINCRACK TEXT.ENC TEXT.DEC 32" will yield TEXT.DEC -- a recognizable version of the cryptography FAQ.