This is the README for zcrypt.1.9.s.tar.gz [Download] [Browse] [Up]
The files described below contain the encryption code for zip 1.9 and unzip 5.0. They constitute only an add-on to the exportable versions (generally named zip19.zip or zip19.tar.Z, and unzip50.tar.Z) and cannot be used without the complete zip package. This encryption code is not copyrighted and is put in the public domain. It was originally written in Europe and can be freely distributed from any country except the U.S.A. If this code is imported in the U.S.A, it cannot be re-exported from the U.S.A to another country. (This restriction might seem curious but this is what US law requires.) However, Phil Katz has said that he got an export license for his algorithm, so this hassle of separate distribution may cease one day. LIKE ANYTHING ELSE THAT'S FREE, ZIP AND ITS ASSOCIATED UTILITIES ARE PROVIDED AS IS AND COME WITH NO WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED. IN NO EVENT WILL THE AUTHORS BE LIABLE FOR ANY DAMAGES RESULTING FROM THE USE OF THIS SOFTWARE. The encryption code is a direct transcription of the algorithm from Roger Schlafly, described by Phil Katz in the file appnote.txt. This file is distributed with the PKZIP program (even in the version without encryption capabilities). Note that the encryption will probably resist attacks by amateurs if the password is well chosen and long enough (at least 8 characters) but it will probably not resist attacks by experts. Short passwords consisting of lower case letters only can be recovered in a few hours on any workstation. But for casual cryptography designed to keep your mother from reading your mail, it's OK. IMPORTANT NOTES: - zip 1.9 is is compatible with pkzip 1.93a, except when two features are used: encryption or zip file created in a pipe or on a non seekable device. pkzip versions of 2.0 will support such files, and unzip 5.0 already supports them. (Thanks to Phil Katz for accepting our suggested minor changes to the zip file format.) - zip files produced by zip 1.9 must not be *updated* by zip 1.0 or pkzip 1.10 or pkzip 1.93a, if they contain encrypted members, or if they have been produced in a pipe or on a non seekable device. The old versions of zip or pkzip would destroy the zip structure. The old versions can list the contents of the zip file but cannot extract it anyway (because of the new compression algorithm). If you do not use encryption and use regular disk files, you do not have to care about this problem. Contents: file what it is ---- ---------- Readme This file. Where where Zip/UnZip can be found crypt.c Code for encryption and decryption zippatch Patch to zip 1.9 makefile unzpatch Patch to unzip 5.0 Makefile zipcloak.c Main routine for ZipCloak. msdos/zipcloak.prj Project file for Borland (Turbo) C++. msdos/zip_cr.prj Project file for Borland (Turbo) C++ (zip with encryption) vms/descrip.mms VMS makefile vms/make_vaxc.com VMS command file for compilation with Vax C. vms/make_gcc.com VMS command file for compilation with gcc. The makefiles not given here should be taken from the original zip 1.9 and unzip 5.0 distributions. They require only minor modifications. Follow the instructions given at the beginning of the makefiles. For example, for the zip 1.9 Unix makefile, remove the comment symbol (#) in: # MAKE = make CRYPTO="crypt.o" CLOAK="zipcloak" CRFLAG="-DCRYPT" to get: MAKE = make CRYPTO="crypt.o" CLOAK="zipcloak" CRFLAG="-DCRYPT" or for the MSDOS makefiles, replace: #CRYPTO=crypt.obj #CLOAK=zipcloak.exe #CRFLAG=-DCRYPT with: CRYPTO=crypt.obj CLOAK=zipcloak.exe CRFLAG=-DCRYPT If you have the 'patch' utility, you can just do: patch < zippatch Similar changes must be made for the unzip Makefile. If you are using the Turbo C integrated environment, you must add CRYPT to the compilation flags and use the project file zip_cr.prj. All of the files are in Unix (LF only) format. On MSDOS systems, you can use the -a option of unzip to convert the source files to CRLF format. This is only necessary if you wish to edit the files -- they will compile as is with Microsoft C and Turbo/Borland C++ 1.0 or later. However, you will have to convert the files (using unzip -a) to the CRLF format to compile with the older Turbo C 1.0 or 2.0. You should be able to find unzip the same place you found this (see the file Where for details).
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.