md5

I'm building a system which needs to be able to find if blobs of bytes have been updated . Rather than storing the whole blob (they can be up to 5MBs), I'm thinking I should compute a checksum of it, store this and compute the same checksum a little bit later, to see whether the blog has been updated. The goal is to minimize the following (in that order) : size of the checksum time to compute likeliness of collisions (2 identical checksums happening even if the content has been modified). It is acceptable for our system to have collision not more than 1/1,000,000. The concern is not security,

I want to know what is the best and fastest implementation of hash algorithms for Java especially MD5 and SHA-2 512 (SHA512) or 256. I want a function to get a string as an argument and return the hash as the result. Thak you. Edit: This is for getting mapping each URL to a unique hash. Since MD5 is not that reliable in this area, I'm more interested in finding the best & fastest implementation for SHA-2 algorithms. Note that I know even SHA-2 might produce the same hash for some URLs but I can live with that. First things first: speed is overrated. You should make measures before declaring

As many will know, one-way encryption is a handy way to encrypt user passwords in databases. That way, even the administrator of the database cannot know a user's password, but will have to take a password guess, encrypt that with the same algorithm and then compare the result with the encrypted password in the database. This means that the process of figuring out the password requires massive amounts of guesses and a lot of processing power. Seeing that computers just keep getting faster and that mathematicians are still developing these algorithms, I'm wondering which one is the most secure

My understanding is that SSL combines an encryption algorithm (like AES, DES, etc.) with a key exchange method (like Diffier-Hellman) to provide secure encryption and identification services between two endpoints on an un-secure network (like the Internet). My understanding is that SASL is an MD5/Kerberos protocol that pretty much does the same thing. So my question: what are the pros/cons to choosing both and what scenarios make either more preferable? Basically, I'm looking for some guidelines to follow when choosing SSL or to go with SASL instead. Thanks in advance! Bruno It's quite

Possible Duplicate: PHP:How to send the original password to the user when he clicks forgot password which is encrypted by using md5? I have create a login and register system in php and I want to make a forgot password link to retrieve password from the database. How I do that? Note: the password in database in encryted using md5 hash MD5 is a cryptographic hash, not an encryption scheme. It cannot be reversed in any direct way. It can only be brute-forced by trying possible passwords until one which matches is found. This is not recommended. You cannot reasonably recover the password. Your

For several cases I would need to create random md5 hashes. Do you know what the best / most secure ways of doing this are? Some use cases Verifying an email address Resetting passwords Some kind of session id used for authentication, instead of password (eg: when someone hits "remember me", I would not like to store the pass in a cookie) Background I know that rand() should not be used for security relevant applications. For that reason I went with: md5( uniqid(mt_rand(),true) ); Now I read in the php manual about uniqid() , that it must not be used for security purposes . Which kind of makes