RxBlFish Manual

By Michal Necasek and Daniel Hellerstein - 25 Feb 2003.

RxBlFish: An OS/2 REXX interface to BlowFish

Summary:
BlowFish is a very powerful encryption tool. RxBlFish provides an OS/2 REXX interfact to BlowFish - with RxBlFish, you can use REXX to encrypt strings and files.

NOTE: This is an update version 1.01 (released in 1999) - it fixes a serious bug that occurs when changing keys under a single process.

I. Requirements
To use RxBlFish, you must have version 1.62 (or above) of BlowFish for OS/2. In particular, you need ENCRYPT.DLL from  version 1.62 (or above).

Due to U.S. export regulations, we can not include ENCRYPT.DLL in this distribution. You'll have to obtain it yourself.


 * U.S. users can find BlowFish for OS/2 on hobbes (http://www.hobbes.nmsu, search for Blowfish).
 * Non U.S. users can find BlowFish for OS/2 on a variety of othersa ites, including:
 * http://www.mirror.ac.uk/sites/hobbes.nmsu.edu/pub/os2/util/encrypt/bfish163.zip and
 * ftp://ftp.flashnet.it/pub/hobbes.nmsu.edu/pub/os2/util/encrypt/bfish163.zip

II. Installation
a) Unzip RXBLFISH.ZIP to an empty temporary directory.

b) Obtain the latest version of the BlowFish (for OS/2) ENCRYPT.DLL (say, by obtaining bfish163.zip and unzipping bfish163 to an empty temporary directory)

c) Copy RXBLFISH.DLL and ENCRYPT.DLL to a directory in your LIBPATH. For example, to x:\OS2\DLL (where x: is your boot drive). That's it - except for writing a REXX program that calls the procedures in RXBLFISH... as described below.

III. Usage
RXBLFISH contains the following procedures: rxBfGetVersion  Get the "version number" rxBfSetVeration Set the "version number" rxBfInitialise  Initialise an encryption key rxBfEncrypt     Encrypt a string or a file rxBfDecrypt     Decrypt a string or a file To load these functions, you can use: call RxFuncAdd 'rxBfGetVersion', 'RXBLFISH', 'rxBfGetVersion' call RxFuncAdd 'rxBfSetVersion', 'RXBLFISH', 'rxBfSetVersion' call RxFuncAdd 'rxBfInitialise', 'RXBLFISH', 'rxBfInitialise' call RxFuncAdd 'rxBfEncrypt',   'RXBLFISH', 'rxBfEncrypt' call RxFuncAdd 'rxBfDecrypt',   'RXBLFISH', 'rxBfDecrypt' Note that you MUST have ENCRYPT.DLL in LIBPATH (or in the default directory) - these RXBLFISH procedures call procedures in ENCRYPT.DLL, but they do NOT elegantly detect if ENCRYPT.DLL is not available.

Before using rxBfEncrypt or rxBfDecrypt, you must "initialise" a key (using rxBfInitialise).

rxBfSetVersion: Set the "version number"
Syntax: status=rxBfSetVersion(nn) Sets the "version number". A non-zero return value indicates an error.

rxBfGetVersion: Get the "version number"
Syntax: status=rxBfSetVersion(nn) Gets the "version number" (as was set by rxBfSetVersion)

rxBfInitialise: Initialise a key
Syntax: status=rxBfInitialise(keyvalue) where keyvalue: a string containing an encryption key. For example: call rxBfInitialise('the key') Note that this string can be of any length (though it has not been tested with strings greater then 80 characters long).

rxBfEncrypt: Encrypt a string or a file
Syntax: enc_stuff=rxBfEncrypt(file_or_string[,fileflag]) where: fileflag is optional.

fileflag=1 : file_or_string is interpreted as a file name. The file will be encrypted, with results saved back to file_or_string. That is, the file specified in file_or_string will be overwritten. A non-zero value of enc_stuff signal an error. fileflag=a file name (relative or fully qualified), The encrypted results are written to fileflag. Thus, the file specified in file_or_string will NOT be overwritten. A non-zero value of enc_stuff signal an error. If fileflag is not specified File_or_string is used as is, with results returned (to enc_stuff). Examples: encstring = rxBfEncrypt("This is a test string to demo Blowfish encryption.") encstring = rxBfEncrypt('foobar.txt',1) status = rxBfEncrypt('foobar.txt','foobar.enc') Note that you MUST call rxBfInitialise before calling rxBfEncrypt.

rxBfDecrypt: Decrypt a string or a file
Syntax: dec_stuff=rxBfDecrypt(file_or_string[,fileflag]) where: fileflag is optional. fileflag=1 : file_or_string is interpreted as a file name. The file will be decrypted, with results saved back to file_or_string. That is, the file specified in file_or_string will be overwritten. fileflag=a file name (relative or fully qualified), The decrypted results are written to fileflag. Thus, the file specified in file_or_string will NOT be overwritten. A non-zero value of enc_stuff signal an error. If fileflag is not specified File_or_string is used as is, with results returned (to dec_stuff).

IV. Example
 call rxBfSetVersion(162) say rxBfGetVersion

call rxBfInitialise('the key')

rc = rxBfEncrypt("This is a test string to show that the Blowfish encryption really works.") say rc

rc = rxBfDecrypt(rc) say "rxBFDecrypt status: " rc

rc = rxBfEncrypt('test.txt', 1) say "rxBFEncrypt (of test.txt) status:" rc rc = rxBfDecrypt('test.txt', 1) say "rxBfDecrypt (of test.txt) status: " rc

rc = rxBfEncrypt('test.txt', 'test.enc') say "Encrypt test.txt to test.enc, status=" rc rc = rxBfDecrypt('test.enc', 'test.dec') say "Decrypt test.enc, save results in test.dec. Status=" rc 

V. Possible future changes

 * support for compression
 * a load procedure