[OWASP_PHPSEC] Second Library - Password Management

Abbas Naderi abiusx at owasp.org
Wed May 29 05:22:05 UTC 2013


Hi all,
Unfortunately your solution is flawed.
1. You can not re-encrypt a hashed content. You will be needing a plaintext password for that.
2. If your passwords are leaked, someone has gained access to your database, and probably has access to your files (read-only) as well. So they just read the password from database.
3. You can not index (B-Tree, Hash) encrypted content in a database, and thus can not query them effectively.
4. A salted and hashed password is secure enough. Encryption does not add extra security.
5. We do not need to hash the password, then send it to server. If we do that, it means that the password is actually the hashed password, so a hacker obtaining the hashed password can send it to server instead of password. Hash challenges are a different story, but yet unnecessary. HTTPS will do it all.

-Abbas
On ۸ خرداد ۱۳۹۲, at ۹:۴۰, rahul chaudhary <rahul300chaudhary400 at gmail.com> wrote:

> so can we do this??
> 
> first user enters their passwords  in plaintext. their passwords gets simply hashed and reaches the server. We encrypt those hashes with a secret key of our own and store that encrypted string in DB (These strings as you pointed out, needs to be stored with extra security). Then we create a random salt and store this salt in DB......Then finally we hash the store encrypted string and the random salt and produce a final hash value stored in our DB...
> 
> 
> PRO: If in case hashes gets stolen, they would anyways be encrypted with our secret key and so we can now do two things --- change the encryption key or change the encryption mechanism....so the user password will still be the same, but the underlying mechanism whole depends on the encryption key......As a side effect...it saves us from rainbow cracks also.
> 
> CONS: It surely will take time because encryption can be bulky sometimes....but this is not much of a problem.
> 
> 
> and for now we can just use SHA-512.



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