07-31-2002
Comparison or storage for later use?
If you're storing for comparison (authentication) purposes (e.g. user enters a password, you save it, then later ask for the password again for verification), then you can store an MD5 hash of the password rather than encrypting and storing the password itself. See Digest::MD5 or Digest::Perl::MD5. Use the second if you are unable to compile C code; it is slower, but should not be noticably slow for something small like passwords.
Using this method, you would take input from the user, and hash it with MD5. The output is a unique string that cannot be reversed to re-obtain the original data. This is useful for password comparison because you can hash the input from the user, then compare the stored value and new value to assure they are the same. The password never has to be stored.
If you're storing for later retrieval and usage then you need a form of encryption that you can reverse with a key. You would use this for encrypting files/data, such as a list of passwords that you want to store for use later. Try Rijndael, Blowfish, Twofish. Of course you need to obtain the key somehow, probably by prompting the user at run-time.
Last edited by kjd; 07-31-2002 at 10:33 PM..
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LEARN ABOUT OSX
openssl-passwd
PASSWD(1SSL) OpenSSL PASSWD(1SSL)
NAME
openssl-passwd, passwd - compute password hashes
SYNOPSIS
openssl passwd [-help] [-crypt] [-1] [-apr1] [-aixmd5] [-5] [-6] [-salt string] [-in file] [-stdin] [-noverify] [-quiet] [-table] [-rand
file...] [-writerand file] {password}
DESCRIPTION
The passwd command computes the hash of a password typed at run-time or the hash of each password in a list. The password list is taken
from the named file for option -in file, from stdin for option -stdin, or from the command line, or from the terminal otherwise. The Unix
standard algorithm crypt and the MD5-based BSD password algorithm 1, its Apache variant apr1, and its AIX variant are available.
OPTIONS
-help
Print out a usage message.
-crypt
Use the crypt algorithm (default).
-1 Use the MD5 based BSD password algorithm 1.
-apr1
Use the apr1 algorithm (Apache variant of the BSD algorithm).
-aixmd5
Use the AIX MD5 algorithm (AIX variant of the BSD algorithm).
-5
-6 Use the SHA256 / SHA512 based algorithms defined by Ulrich Drepper. See <https://www.akkadia.org/drepper/SHA-crypt.txt>.
-salt string
Use the specified salt. When reading a password from the terminal, this implies -noverify.
-in file
Read passwords from file.
-stdin
Read passwords from stdin.
-noverify
Don't verify when reading a password from the terminal.
-quiet
Don't output warnings when passwords given at the command line are truncated.
-table
In the output list, prepend the cleartext password and a TAB character to each password hash.
-rand file...
A file or files containing random data used to seed the random number generator. Multiple files can be specified separated by an OS-
dependent character. The separator is ; for MS-Windows, , for OpenVMS, and : for all others.
[-writerand file]
Writes random data to the specified file upon exit. This can be used with a subsequent -rand flag.
EXAMPLES
% openssl passwd -crypt -salt xx password
xxj31ZMTZzkVA
% openssl passwd -1 -salt xxxxxxxx password
$1$xxxxxxxx$UYCIxa628.9qXjpQCjM4a.
% openssl passwd -apr1 -salt xxxxxxxx password
$apr1$xxxxxxxx$dxHfLAsjHkDRmG83UXe8K0
% openssl passwd -aixmd5 -salt xxxxxxxx password
xxxxxxxx$8Oaipk/GPKhC64w/YVeFD/
COPYRIGHT
Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the OpenSSL license (the "License"). You may not use this file except in compliance with the License. You can obtain a
copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>.
1.1.1a 2018-12-18 PASSWD(1SSL)