Compression, Encoding, Encryption
Utils for DOS

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This page remains incomplete:add PGP to the encryption section, add a better variety of encoder-decoder utils. See Yves Bellefeuille's list of best freeware for DOS and Win 3.1 for a more comprehensive listing and some different favorite picks.


ARCHIVERS


Info-Zip- PkZip compatible file archiver

* * * * [updated 12-2-98]

"Compatible" does not equate to a cheap knock-off or clone in the case of Info-Zip. Info-Zip is format compatible with PkZip- but the resemblance ends there. The command line syntax varies from PkZip/Unzip, and additional options have been introduced. Info-Zip was developed to provide cross-platform PkZip compatibility across a variety of operating systems (DOS/Win, Unix, OS/2, Mac, VMS, Linux, Amiga, Acorn, SGI, Atari, etc.). Info-Zip Web Site.

Although Zip still can't span a zip file across multiple floppies (coming in next version!), it does most everything else as well as PKZip (compression size, speed). Zip has one compression method (deflation) and can store files without compression. Although creation of self-extracting EXE's is possible- it's not elegant, adds 30K to file size, and creates a file potentially not readable by PKZIP compatible viewers.

To create an SFX you'll need to join UNZIPSFX.EXE (distributed with unzip*.exe) to a zip file created by ZIP. For example,

COPY UNZIPSFX.EXE + MY.ZIP MY.EXE /B
ZIP -A MY.EXE
(make it a technically valid zip file)

An alternate ZIP package (ZCRx.ZIP) contains an encryption program so that you can encrypt-protect your ZIP files. For legal reasons, the encryption capable version is not exportable abroad from US sites- I'm providing links to European sites.

12-98: new UNZIP version 5.40 released: - changed listing formats to enlarge the file size fields for more digits; - added capability to restore directory attributes on MSDOS, OS/2, WIN32; - GUI SFX stub for Win16 (Windows 3.1) and Win32 (Windows 9x, Windows NT); - new free GCC compiler environments supported on WIN32; - many time-zone handling bug fixes for WIN32, AMIGA, ...

  • Info-Zip for DOS :
    1. DOS UNZIP: download unz540x3.exe (240K, 16 & 32-bit versions)
    2. DOS ZIP: download zip22x.zip (184K, 16 & 32-bit versions);
    3. Wiz for Win 3.1: download wiz401x.exe (330k)
  • Info-Zip for Win 95/NT :
    1. Win 95/NT UNZIP: download unz540xN.exe (240K)
    2. Win 95/NT ZIP: download zip22xN.zip (136K)
    3. Wiz for Win95/NT (GUI version): download wiz401xN.exe (456K)


    UC2- Archiver compresses files tighter than PKZIP (but...)

    * * * *

    ...but PKZIP is the standard, regardless of it's shortcomings. UC2 is one of several file compression programs that is trying to unseat PKZIP from its dominant market position. While UC2 is not "freeware" it is free for individual use. UC2's method of compression involves analyzing files for content type prior to compression. This allows a smarter and tighter compression of a set of files than is possible with PKZIP. The cost is slightly longer compression times.

    Other nice features:

    UC2's principal drawback is it's inability to span files across multiple floppy diskettes (includes a separate utility that performs this task). UC2 compression seems to require a large amount of memory (consistently fails under Windows on my 8MB system). UC2 may leave temp files on disk. UC2 has never achieved the popularity of PkZIP, ARJ, RAR, or LHA and has not seen an update in over two years. Author AIP-NL, Home Page.

    download uc2pro.exe (400K)

    or uc237b.exe (400K, beta, Win95 support)


    LHA- Archiver also creates freely distributable self extracting archives.

    * * *

    LHA is an older archiver which shares similar compression statistics with PKZip. Unlike PKZip, Arj, UC2, and RAR, LHA is true freeware, and self-extracting archives created by LHA may be freely distributed. Author: Haruyasu Yoshizaki. (1992; documentation-1996).

    download lha255e.exe (65K, LHA SFX)


    X1 -Super tight file archiver can also compress to common archive formats.

    unrated

    Although an interesting program, X1 is not recommended to most casual users of compression programs. But if you desire to create smaller archives than is possible with PKZIP, ARJ, LHA, or UC2 -and don't mind the longer compression time- you might want to try X1. X1 compresses text documents significantly better than PKZIP/Info-Zip and UC2. The degree of compression advantage for X1 is less for some file types (e.g., programs, binaries). Here is a quick and dirty compression size comparison of X1, PKZip, and UC2:

    TXT file test:
    Compress 8 ASCII files, total size= 1.8 MB, into single archive.
    Archiver... Options .. Result
    X1......... axm4 ..... archive size= 519 K, % orig. size= 28
    X1......... axm1 ..... archive size= 650 K, % orig. size= 36
    PKZIP...... ex ....... archive size= 668 K, % orig. size= 37
    UC2........ att ...... archive size= 650 K, % orig. size= 36

    EXE file test:
    Compress 24 DOS/Win EXE files, total size= 1.74 MB, into single archive.
    Archiver... Options .. Result
    X1......... axm4 ..... archive size= 771 K, % orig. size= 44
    X1......... axm1 ..... archive size= 793 K, % orig. size= 45
    PKZIP...... ex ....... archive size= 814 K, % orig. size= 46
    UC2........ att ...... archive size= 791 K, % orig. size= 45

    Notes:

    Possible disadvantages of X1:

    Author: Stig Valentini (1997)

    download x1dos95a.zip (298K)


    UnRAR- Unpacks RAR archives.

    unrated [updated 10-02-99]

    UnRAR is the freeware unpacker for RAR compressed files. Since the RAR archiver is shareware, I will not describe it's terrific features except to note that it is becoming a more popular format on eastern European FTP sites, BBS's, and FIDONET. The freeware unrar.exe is included in the RAR package.

    download rar250.exe (270K, RAR and UNRAR; RAR SFX); source code only: unrar250.zip (72K)


    OTHER ARCHIVERS OF INTEREST:

    unrated [section added 12-15-98]


    EXE COMPRESS AND UNPACK

    Familiar to most programmers and power users- but if you're obsessed with saving disk space you might want to experiment with these programs (note: If you already use disk compression software these utils won't save you much space). Power users: also see the Sudden Discharge site.


    all unrated

    1. UPX- Tight and versatile 32-bit DOS and WIN32 exe compressor.
    2. 32LiTE- Tight and versatile 32-bit DOS exe compressor.
    3. aPACK- Super tight EXE and COM compressor.
    4. LzExe- Compresses many executables into smaller, functional programs.
    5. Diet- Compresses executables (including overlays) and com files.
    6. DJP- Compressor/ decompressor for 32-bit DJGPP EXE's.
    7. ComToExe -Converts Com files to Exe.
    8. UNP -Unpacks compressed executables.
    9. CUP -Unpacks many compressed executables.
    10. GetTyp -Identify packer origin of many compressed executables.
    1. UPX: [updated 11-16-99] Maybe the most versatile exe format packer on the scene- and it's free. Because it's still undergoing beta testing, it should only be used for testing purposes (bugs possible, compatibility between releases is not guaranteed). Distinguished from the other packers listed here by its combination of tight compression and an ability to pack a diverse array of executable formats including : dos/exe, sys, & com, djgpp2/coff, watcom/le (e.g., DOS4G, PMODE/W, etc.), win32/pe (e.g., Netscape.exe), rtm32/pe, tmt/adam. Fast decompression; no memory overhead, and can also list, test, and unpack. Win32 and Linux versions also available on Home Page. Authors: Markus F.X.J. Oberhumer and László Molnár (1999).
      • 11-15-99: beta 0.92 released. See docs for version history.
      • download upx092d (156K; protected mode DOS version)
    2. 32LiTE: [added 07-14-99] Untested. This packer claims to pack a wider variety of DOS exe formats than UPX (e.g., WDOS/X, DOS32, W32RUN, PHARLAP, "P3", and mixed format exe's) and relies on APACK code for good compression. Author: Oleg Prokhorov (1999).
    3. aPACK: [added 7-7-98; updated 3-14-99] An EXE and COM packer that's currently (1999) in the running for the honor of tightest DOS EXE/COM packer available. Excels with smaller files. See docs, Home Page, or the latest ACT results for some head to head comparisons. Requires a 386+ with at least 4MB RAM. Free for non-commercial use only. Suggested by Lars-Erik Sandberg. Author: Joergen Ibsen, Denmark. (1999)
    4. LzExe: An older but widely used exe packer. Executables with overlays cannot be compressed. Saves a backup of the original exe.
    5. Diet: I haven't looked much at this program but it compresses files that LzExe can't: exe's with overlays (with some preconditions) and COM files.
    6. DJP: [added 8-16-98] Designed to pack (and unpack) 32-bit programs produced with DJGPP. I tested DJP on the v332 LESS.EXE and reduced the size from around 162K down to 95K; GREP.EXE from 122K to 69K. Author: Laszlo Molnar (1998). Also see DJP's successor, UPX.
    7. ComToExe: Converts a *.com file into an *.exe file (many exe compressors don't pack com files). Included in the LzExe package.
    8. If you need to un-compress a packed-exe (perhaps to pack with a tighter compressor), try a universal decompressor tool such as UNP. Becoming a bit dated, but simple to use.
    9. CUP: (aka UCFCUP, CUP386). Regularly cited as one of the best EXE unpackers around- it was developed primarily for hackers and others with a programming bent. Although CUP has many debugging and other power-user options, it is often capable of unpacking many formats in one easy step, and that's why I include it here. CUP has been tested with the following formats -but was designed to unpack executables packed with unknown software: PkLite, Diet, LzExe, TinyProg, PgmPak, HackStop, WWPack. Requires a 386+. CUP functions best when memory managers (e.g., EMM386) are not loaded. Development has ended (8-97).
    10. GetTyp: Identify packer of compressed executables. See extended description.


    UUE and MIME ENCODE-DECODE


    UUdeview- UUE, XX, Base 64 (MIME), en/ decode. Decodes BINHEX.

    * * * * *

    A good, simple-to-use, multi-platform encoder and decoder package. UUEnview is capable of encoding files into UUE, XX-UUE, and Base 64 (MIME) formats. UUDeview can decode all of these plus the Macintosh BINHEX (*.hqx) format. UUDeview handles sequential and multipart files well. The program runs interactively- allowing one to make decoding decisions (e.g., renaming) based on the contents of the encoded message. Batch processing is also possible. The executable file sizes are a tad large compared to other DOS encode/decode utilities (100k each for encoder and decoder). Author: Frank Pilhofer. Germany (1997).


    ENCRYPTION

    Need to add public key programs like PGP. The IDEA and Blowfish algorithm private key programs listed here should be the most secure but I make no personal claims. If you want to prevent your mom or little brother from reading your love notes, any encryptor listed here should do the trick. If your mom works for the CIA, or if you intend to send/ receive sensitive information over the Net, I'd start at a different web page (e.g., See http://cryptography.org/ ).


    Z-Crypt- Small, fast file encryption/decryption program.

    * * *

    A private key file encryption program- small, fast, and "anonymous." While Z-Crypt does not implement a well-tested cipher, it does combine several features that attempt to ensure the anonymity of encrypted files. During encryption, Z-Crypt can scramble the file name, it overwrites the original file (caution!), and it can easily be used in batch files. Probably sufficient for non-critical needs, but cryptography experts probably wouldn't recommend it for high security uses. Unlike Tiny IDEA, Z-crypt only accepts a 1-word password, not a passphrase. A password must be typed on the command line, or included in a batch file- so there is a risk of it being seen by others. Don't forget the password. Source included.

    From the documentation: "*Z*Crypt is different than other file encryption programs mainly due to it's "anonymity" objectives. The driving concept behind *Z*crypt was to create a scheme whereby when the selected files have been encrypted there remains absolutely no clue as to that file's original identity or purpose. There are two reasons for this. ...A person may encrypt files with another file encryption scheme securely, but if the file name or extension is identifiable then others may be able to discern what 'types' of files are being encrypted, which could arouse unwanted curiosities or suspicions. Similarly, most other file encryption programs leave identifiable 'signatures' in the encrypted file so the decryption routines can positively identify the file as being encrypted by it. *Z*Crypt leaves absolutely no identifiable header of any kind in it's encrypted files.... It is up to you to know which files you have encrypted. The second reason for 'anonymity' is that leaving clues as to the 'type' of file that has been encrypted is a major foothold for any would-be hacker. Using known patterns that may exist in known formats of known 'types' of files (even known types of encryption) is a common starting point for cracking open encrypted files. *Z*Crypt leaves no such vestiges."

    download zc031.zip (contains both DOS and OS/2 executables.)


    Tiny IDEA- Small IDEA file encryptor and decryptor.

    * * * * [updated 1-3-99]

    Tiny IDEA is a tiny (500 bytes) private key file encryption program that uses the IDEA cipher. It is used to scramble files with a key, such that the original file cannot be recreated without knowledge of the key. Because Tiny IDEA overwrites files during encryption, it can also be used to destroy sensitive files. Does not scramble file names. Author: Fauzan Mirza, w/optimizations by B. Couture and M. Andreas. UK. (1996)

    From the documentation:

    "IDEA operates on 64-bit data blocks using a 128-bit key. No method of cracking IDEA faster than exhaustive key search (brute force) has been discovered, despite extensive analysis by professional cryptologers. As an example of IDEA's strength, imagine an incredibly fast computer that can brute force a 56-bit DES key in 1 second. This computer would take upto 194 days to crack a 80-bit key, like the one used by the NSA Skipjack cipher, and up to 149745258842898 years to crack a 128-bit IDEA key."

    download idea3a.zip (version 3a, 19K)

    Update 1-3-99: Mark Andreas has recently (12-98) released version 4 of Tiny IDEA, but note that it is export restricted from the USA. Some of the changes in v4.0 include smaller size (366 bytes), passphrase can be put on the command line, more. This distribution includes several variations, with different combinations of features. See Mark's crypto pages for version 4 availability and an in-depth description.


    TinyFish- 5K Blowfish file encryptor.

    unrated [added 9-25-98]

    Designed along the same lines as Tiny IDEA, but uses a Blowfish algorithm.

    Author: Dutra Lacerda, Portugal (1998)

    download tinyfish.zip (10K)


    Blowfish-CBC- Blowfish file encryptor.

    unrated [added 9-25-98]

    A simple private key file encryption program that uses a CBC implementation of the BlowFish algorithm.

    Usage:

      BLW-CBC (E|D) <PassFrase> <InputFile> [<OutputFile>]
               | |                   |            |
    Encrypt ---+ +--- Decrypt     Origin!  Optional Argument
    

    Author: Dutra Lacerda, Portugal (1998)

    download blwcb15a.zip (37K)


    SNOW- Conceal text message in an ASCII file.

    unrated [added 5-9-98 updated 1-17-99]

    "...Snow is used to conceal messages in ASCII text by appending whitespace to the end of lines. Because spaces and tabs are generally not visible in text viewers, the message is effectively hidden from casual observers. And if the built-in encryption is used, the message cannot be read even if it is detected....If a message string or message file are specified on the command-line, snow will attempt to conceal the message in the file infile if specified, or standard input otherwise. The resulting file will be written to outfile if specified, or standard output if not. If no message string is provided, snow attempts to extract a message from the input file. The result is written to the output file or standard output."

    If a message (or message file) cannot be fit into the host file's available "free space," lines will be appended to the end of the file. An option does exist to adjust the length of lines which increases available message space. Optional encryption of the message is supported using the 64-bit ICE encryption algorithm in 1-bit cipher-feedback mode. Passwords can (theoretically) be up to 1170 characters in length. Simple compression of the message is also possible. Note that the original and message-containing files may differ in size, and there is no special, secure handling of passwords. Win32 console, Unix and Java versions are available from the author's page. Author: Matthew Kwan, Australia. (1998)

    Update 1-17-99: New in v11-22-98: "Files concealed with encryption using the DOS version could not be decrypted by the other versions, and vice versa....This has now been fixed...The source version, when compiled under Unix, also had a bug where it could not read data concealed by the DOS version, owing to the carriage return character appended by DOS. This has also been fixed..."

    download snowdos16.zip (27K)


    PASSWORD GENERATORS


    1. KeyGen- Auto-generates multiple passphrases; saves to file; configurable.

    unrated [added 9-12-98]

    This program quickly generates multiple passphrases and automatically saves them to a user-named file. The program allows you to set options from a set-up screen: use upper and/or lower case alphabet, and/or numbers, and/or special characters; define passphrase length (10-80 characters); and define number of passphrases generated (1-999). No description of algorithm used, no source. Author: Zoltan Pupp, Hungary (1997).

    download keygen.zip (8K)


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