f0d81ffd1c
which included commits to RCS files with non-trunk default branches. git-svn-id: svn://10.65.10.50/trunk@5403 c028cbd2-c16b-5b4b-a496-9718f37d4682
75 lines
3.8 KiB
Crystal
Executable File
75 lines
3.8 KiB
Crystal
Executable File
__________________________________________________________________________
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This is the Info-ZIP README.CR for zcrypt27.zip, last updated 28 Mar 97.
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__________________________________________________________________________
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The files described below contain the encryption code for Zip 2.2 and
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UnZip 5.3 (and later). They constitute only an add-on to the exportable
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versions (generally named zip22.zip and unzip53.tar.Z) and cannot be
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used without the complete Zip or UnZip packages.
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This encryption code is not copyrighted and is put in the public domain.
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It was originally written in Europe and can be freely distributed from
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any country except the U.S.A. If this code is imported into the US, it
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cannot be re-exported from the US to another country. (This restriction
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might seem curious but this is what US law requires.) However, Phil Katz
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has said that he got an export license for his algorithm, so this hassle
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of separate distribution may cease one day.
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LIKE ANYTHING ELSE THAT'S FREE, ZIP, UNZIP AND THEIR ASSOCIATED UTILITIES
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ARE PROVIDED AS IS AND COME WITH NO WARRANTY OF ANY KIND, EITHER EXPRESSED
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OR IMPLIED. IN NO EVENT WILL THE AUTHORS BE LIABLE FOR ANY DAMAGES
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RESULTING FROM THE USE OF THIS SOFTWARE.
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The encryption code is a direct transcription of the algorithm from
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Roger Schlafly, described by Phil Katz in the file appnote.txt. This
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file is distributed with the PKZIP program (even in the version without
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encryption capabilities). Note that the encryption will probably resist
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attacks by amateurs if the password is well chosen and long enough (at
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least 8 characters) but it will probably not resist attacks by experts.
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Paul Kocher has made available information concerning a known-plaintext
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attack for the PKWARE encryption scheme; see http://www.cryptography.com/
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for details.) Short passwords consisting of lowercase letters only can be
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recovered in a few hours on any workstation. But for casual cryptography
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designed to keep your mother from reading your mail, it's OK.
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For more serious encryption, check into PGP (Pretty Good Privacy), a
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public-key-based encryption system available from various Internet sites.
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PGP has Zip and UnZip built into it. The most recent version at the time
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this was written was 2.6.2 (and 2.6.3i for non-US users).
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Zip 2.2 and UnZip 5.3 are compatible with PKZIP 2.04g. (Thanks to Phil
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Katz for accepting our suggested minor changes to the zipfile format.)
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IMPORTANT NOTE:
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Zip archives produced by Zip 2.0 (or later) must not be *updated* by
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Zip 1.1 or PKZIP 1.10 or PKZIP 1.93a, if they contain encrypted members
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or if they have been produced in a pipe or on a non-seekable device.
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The old versions of Zip or PKZIP would destroy the zip structure. The
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old versions can list the contents of the zipfile but cannot extract
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it anyway (because of the new compression algorithm). If you do not
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use encryption and use regular disk files, you need not worry about
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this problem.
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Contents:
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file what it is
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---- ----------
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README.CR this file
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Where where Zip/UnZip and related utilities can be found
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crypt.c code for encryption and decryption (for Zip and UnZip)
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crypt.h code for encryption and decryption (for Zip and UnZip)
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file_id.diz description file for some BBSes
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All of the files are in Unix (LF only) format. On MSDOS systems, you
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can use the -a option of UnZip to convert the source files to CRLF
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format. This is only necessary if you wish to edit the files -- they
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will compile as is with Microsoft C and Turbo/Borland C++ 1.0 or
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later. However, you will have to convert the files (using "unzip -a")
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to the CRLF format to compile with the older Turbo C 1.0 or 2.0. You
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should be able to find Zip and UnZip in the same place you found this
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(see http://www.cdrom.com/pub/infozip/ or the file "Where" for details).
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