Magento - modifying a core database

I would like to use a different encryption algorithm than the default md5 algorithm开发者_StackOverflow社区 in Magento and am looking at a good way to implement this.

Currently I made an extension which features its own encryption class, replacing the Mage_Core_Model_Encryption class in the config. This works succesfully, but there is a small problem. My encryption uses more than the 40 characters allowed for a password in the database.

How would I go and modify this value in a correct way?

Make a setup file in my extension which modifies the admin_user table?

- or -

Overwrite the setup/install file for Mage_Admin_Model_User and modify the table to my needs?

(- or - not what I would like, but the easiest: modify it manually in the database)

I am confused..

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The first option - "Make a setup file in my extension" - makes the most sense to me.

Also see how to alter a table without SQL.