Re: [PHP-DB] MD5, MySQL, and salts
On 4/18/06, Giff Hammar [EMAIL PROTECTED] wrote: For an example, look at how UNIX/Linux stores regular login passwords. In short, the salt is the first two characters in the password. When comparing passwords, you take the salt and the user supplied password, encrypt, then compare the two encrypted strings. If they match, the recently supplied password matches the original. AFAIK, that is the only way to verify passwords encrypted with a one-way algorithm. I badly worded my response, but yes you're right. Anyway I found the article I was thinking of: http://phpsec.org/articles/2005/password-hashing.html (which ironically suggests the opposite of what I said - use a random salt :P). -- Postgresql php tutorials http://www.designmagick.com/ -- PHP Database Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
[PHP-DB] MD5, MySQL, and salts
Hi Guys, I'm working on securing user passwords in a MySQL 4 database with a PHP5 frontend. I remember being told in one of my classes (I'm currently a college junior) that the best way would be to hash a salt and the password together and then store the hash in the database instead of the plain MD5 hash. My question is, what is a good method for the server and the database to agree on a salt value to use? I know i could use a predefined variable, but I was wondering if something dynamic might be better (timestamp, current date, something like that). Any ideas? Thanks in advance! -Sean
Re: [PHP-DB] MD5, MySQL, and salts
On 4/18/06, Sean Mumford [EMAIL PROTECTED] wrote: Hi Guys, I'm working on securing user passwords in a MySQL 4 database with a PHP5 frontend. I remember being told in one of my classes (I'm currently a college junior) that the best way would be to hash a salt and the password together and then store the hash in the database instead of the plain MD5 hash. My question is, what is a good method for the server and the database to agree on a salt value to use? I know i could use a predefined variable, but I was wondering if something dynamic might be better (timestamp, current date, something like that). Any ideas? Thanks in advance! If it's a dynamic salt, how are you going to access it when you have to compare ? There was an article either on phpsec.org or shiflett.org which talks about this.. can't find the link right now :( -- Postgresql php tutorials http://www.designmagick.com/ -- PHP Database Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
RE: [PHP-DB] MD5, MySQL, and salts
For an example, look at how UNIX/Linux stores regular login passwords. In short, the salt is the first two characters in the password. When comparing passwords, you take the salt and the user supplied password, encrypt, then compare the two encrypted strings. If they match, the recently supplied password matches the original. AFAIK, that is the only way to verify passwords encrypted with a one-way algorithm. Giff -Original Message- From: chris smith [mailto:[EMAIL PROTECTED] Sent: Monday, April 17, 2006 4:36 PM To: Sean Mumford Cc: php-db@lists.php.net Subject: Re: [PHP-DB] MD5, MySQL, and salts On 4/18/06, Sean Mumford [EMAIL PROTECTED] wrote: Hi Guys, I'm working on securing user passwords in a MySQL 4 database with a PHP5 frontend. I remember being told in one of my classes (I'm currently a college junior) that the best way would be to hash a salt and the password together and then store the hash in the database instead of the plain MD5 hash. My question is, what is a good method for the server and the database to agree on a salt value to use? I know i could use a predefined variable, but I was wondering if something dynamic might be better (timestamp, current date, something like that). Any ideas? Thanks in advance! If it's a dynamic salt, how are you going to access it when you have to compare ? There was an article either on phpsec.org or shiflett.org which talks about this.. can't find the link right now :( -- Postgresql php tutorials http://www.designmagick.com/ -- PHP Database Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php -- PHP Database Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP-DB] MD5, MySQL, and salts
This begs the question of what would this method buy you over MD5? Some people have issue with like passwords looking the same with MD5 encryption, also a one way hash. But if you know the salt, then like passwords would also look the same, right? -B Giff Hammar wrote: For an example, look at how UNIX/Linux stores regular login passwords. In short, the salt is the first two characters in the password. When comparing passwords, you take the salt and the user supplied password, encrypt, then compare the two encrypted strings. If they match, the recently supplied password matches the original. AFAIK, that is the only way to verify passwords encrypted with a one-way algorithm. Giff -Original Message- From: chris smith [mailto:[EMAIL PROTECTED] Sent: Monday, April 17, 2006 4:36 PM To: Sean Mumford Cc: php-db@lists.php.net Subject: Re: [PHP-DB] MD5, MySQL, and salts On 4/18/06, Sean Mumford [EMAIL PROTECTED] wrote: Hi Guys, I'm working on securing user passwords in a MySQL 4 database with a PHP5 frontend. I remember being told in one of my classes (I'm currently a college junior) that the best way would be to hash a salt and the password together and then store the hash in the database instead of the plain MD5 hash. My question is, what is a good method for the server and the database to agree on a salt value to use? I know i could use a predefined variable, but I was wondering if something dynamic might be better (timestamp, current date, something like that). Any ideas? Thanks in advance! If it's a dynamic salt, how are you going to access it when you have to compare ? There was an article either on phpsec.org or shiflett.org which talks about this.. can't find the link right now :( -- Postgresql php tutorials http://www.designmagick.com/ -- -- PHP Database Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP-DB] MD5, MySQL, and salts
True in some form, it always comes down again to the strength and integrity of the original password. Yes, even if a salt is unknown and it is a plain text, dictionary password, then it doesn't take much for a brute force attempt at just using the first two characters of each word and salting it with the word to create the hash and seeing if it matches. But just knowing the two character salt doesn't overly help in decrypting the hash. Using a custom hash particularly using part of the key itself as the hash increases the integrity and uniqueness of the hash by an exponential factor. You have two values now that are affecting the hash output value. Something to chew on... -J B This begs the question of what would this method buy you over MD5? Some people have issue with like passwords looking the same with MD5 encryption, also a one way hash. But if you know the salt, then like passwords would also look the same, right? -B Giff Hammar wrote: For an example, look at how UNIX/Linux stores regular login passwords. In short, the salt is the first two characters in the password. When comparing passwords, you take the salt and the user supplied password, encrypt, then compare the two encrypted strings. If they match, the recently supplied password matches the original. AFAIK, that is the only way to verify passwords encrypted with a one-way algorithm. Giff -Original Message- From: chris smith [mailto:[EMAIL PROTECTED] Sent: Monday, April 17, 2006 4:36 PM To: Sean Mumford Cc: php-db@lists.php.net Subject: Re: [PHP-DB] MD5, MySQL, and salts On 4/18/06, Sean Mumford [EMAIL PROTECTED] wrote: Hi Guys, I'm working on securing user passwords in a MySQL 4 database with a PHP5 frontend. I remember being told in one of my classes (I'm currently a college junior) that the best way would be to hash a salt and the password together and then store the hash in the database instead of the plain MD5 hash. My question is, what is a good method for the server and the database to agree on a salt value to use? I know i could use a predefined variable, but I was wondering if something dynamic might be better (timestamp, current date, something like that). Any ideas? Thanks in advance! If it's a dynamic salt, how are you going to access it when you have to compare ? There was an article either on phpsec.org or shiflett.org which talks about this.. can't find the link right now :( -- Postgresql php tutorials http://www.designmagick.com/ -- -- PHP Database Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php -- No virus found in this incoming message. Checked by AVG Anti-Virus. Version: 7.1.384 / Virus Database: 268.4.2/314 - Release Date: 16/04/2006 -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.1.384 / Virus Database: 268.4.2/314 - Release Date: 16/04/2006 -- PHP Database Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
RE: [PHP-DB] MD5, MySQL, and salts
you need the key to be easily available, so row id or a set date field(one that does not change as opposed to a timestamp type field) bastien From: Sean Mumford [EMAIL PROTECTED] To: php-db@lists.php.net Subject: [PHP-DB] MD5, MySQL, and salts Date: Mon, 17 Apr 2006 15:33:58 -0400 Hi Guys, I'm working on securing user passwords in a MySQL 4 database with a PHP5 frontend. I remember being told in one of my classes (I'm currently a college junior) that the best way would be to hash a salt and the password together and then store the hash in the database instead of the plain MD5 hash. My question is, what is a good method for the server and the database to agree on a salt value to use? I know i could use a predefined variable, but I was wondering if something dynamic might be better (timestamp, current date, something like that). Any ideas? Thanks in advance! -Sean -- PHP Database Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
