A hash algorithm is a function which takes a variable size input and produces a fixed size output. The algorithm tries to make it difficult to predict the output for a given input, find two inputs with the same output, or reconstruct the input from the output.

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Use the hash of the password to encrypted password

I have a app which transmit the password in clear text. I was planning to use the hash of the password (SHA-512) as the key for encrypting the plain text password. Then send the encrypted text to the ...
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Why do most hashing functions produce hashes that have characters a-f 0-9?

This is something I never understood about hashing functions. I know that algorithms like whirlpool and blowfish both produce outputs that don't follow this pattern, but why is it that most do? Is ...
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Is this security/encryption scheme secure?

I'm rolling my own, personal threetags.com-style 'encrypted data in the cloud' webapp (I didn't like the UI, and lack of non-browser client). However, I have absolutely no experience with security ...
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Salted hashes vs HMAC?

Most of discussions involving access credentials include references to "hashing salted passwords". Is this another way to referring to the HMAC algorithm or a totally different operation? Different or ...
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What is the purpose of a Pepper?

I've been trying to find out exactly what a pepper is. The only things I could accurately determine are that a Pepper: Is theoretically unique from site to site and hard-coded in the site's source ...
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What is better salted hash or openssl encryption?

Im using php and I was looking to store passwords in a mysql database. I was wondering what would be safer to use a salted hash or openssl encryption? If i use a unique random generated salted hash ...
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Windows 7 Password Hash Security

I recently came across a number of sources that suggest that cracking Windows user account passwords is easy by examining their password hashes. I understand that these hashes are stored in the SAM ...
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Can DES-based hashed password be recovered if salt is known?

Can a hashed password be recovered if the hashing is done with DES based crypt function in PHP and both the hash and salt are known by the attacker? Consider the following example: $salt = 'mysalt'; ...
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usernames and passwords

I was thinking about usernames and passwords and I was wondering how secure it would be to instead of the server having a list of usernames and accompanying hash of the passwords, just have a list of ...
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Why not hashing and salting passwords?

When I was implementing my webapp, I decided to hash and salt users' passwords in order to protect them, even though I knew that there will never be a lot of them ... if any. Of course, I'm not saying ...
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Rounds of MD5 and SHA512 Hashing Algorithms

What is the exact number of rounds employed by the MD5 and SHA512 hashing algorithms? According to various sources, the SHA512 hashing algorithm employs a total of 80 rounds ...
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Can the salt for PBKDF2 be a hash of the user-entered password?

I want to derive a key from a password in a client application that will be used as a master key that decrypts a data key. As far as I understand the salt should be private knowledge. Would it be ...
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Salting a public hash

Does it make any sense at all to salt a hash which might be available publicly? It doesn't really make sense to me, but does anyone actually do that? UPDATE - Some more info: An acquaintance of ...
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What security purpose do hashes of files serve?

Many websites offering downloads also provide the MD5 or SHA1 hashes of the files which are available for download. An example- What is the security purpose behind providing such a facility to the ...
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How does processor architecture affect password hashing speed?

Does hashing speed vary significantly using different architectures (x86 vs ARM)? Scenario I am investigating the possibility of using a cluster of Raspberry Pi for cracking passwords hashed with ...
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Tracking unique web site visits without logging IP addresses

On Monday, some IP address xxx.xxx.xxx.xxx visits my site. I log it. On Tuesday, another IP address yyy.yyy.yyy.yyy visits my site. I log it. If the two IP addresses are equal, I throw out the ...
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symetric key encryption vs hashing

This is a fascinating document: top 100 passwords from adobe breach I have a question about one part of it: However, thanks to Adobe choosing symmetric key encryption over hashing, selecting ...
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Is it good practice to SHA512 passwords prior to passing them to bcrypt?

I want to allow any-sized passwords to be allowed to be submitted. I currently use bcrypt as a key derivation function for passwords, however I have realized that it has a maximum input length of 72. ...
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Why does MD5 hash starts from $1$ and SHA-512 from $6$? Isn't it weakness in itself? [duplicate]

I have moved this question from stackoverflow to this place. I know it may be a question about 'opinion' but I am not looking for a private opinion but a source of the final decision to keep it this ...
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How can I check the integrity of the downloaded files?

I know we use hash functions to check for the integrity of the files etc... but my question is how can we check for the integrity of the files being downloaded from some server?
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When hashing passwords, is it okay to store the algorithm used right there in the database?

Since hashing password has become a hot topic recently, it is only natural to expect things to change and assume that some time down the road you might want to replace/tweak the algorithm used in your ...
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Hashed passwords - How many variations of rainbow tables?

First off...I passed the CISSP exam. WOOOO. I had to get that out. GCIH and CEH by Sept. 11' So, while studying for the technical side of things, I see that there are rainbow tables. They are ...
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417 views

Client-Side Hashing to decrease value of password guessing heuristics

Yes, this is 'yet another client-side hashing' question. But, don't leave yet, I think there is some value here. I'd like to do something to mitigate the affect on the community as a whole when my ...
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What is the purpose of using Youtube-style alphanumeric ids as URL slugs?

I asked a question on StackOverflow on how to generate the alphanumeric/base64 resource IDs that Youtube, Instragram, and others use to identify videos/pictures/etc. Discussion led to the question of ...
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OS Kernel Hashing

Has anyone had experience with or is aware of any products that hash the OS kernel? This would be used, ideally, for watching for system compromises, auditing, change management, etc. I am looking ...
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Is it safe to use PBKDF2 for hashing?

I would like to get a few opinions on whether it would be safe or not to use PBKDF2 to generate a hash of a password. For my purposes I'd like to assume that the hash itself will be posted on the ...
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User password as key instead of hashing it

I was reading here on Hashes and Salts and I thought about another method to do user authentication. I need your thoughts on this as I might be overlooking something. Scenario: For web application ...
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should i use urandom or openssl_random_pseudo_bytes?

I am developing a site in php 5.4 and i was wondering which is better to use to gen a random salt for password security? $salt = sha1(openssl_random_pseudo_bytes(23)); or $seed = ''; $a = ...
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Is there a hash algorithm that can identify similar files or strings?

Is there a hash algorithm that will help you identify similar files or strings? For example, the hash for ABC and XBC would be similar rather than radically different as is usually the case. I know of ...
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Expanding/Inverse Hash function

First off, before I ask my question, let me explain what I am NOT asking. I am NOT asking for a way/method to reverse a hash output; by definition, a hashing function is one-way. Is there such a ...
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Hashing a key: less entropy than the key itself

A web API needs to store a 'key' for authentication, in much the same fashion as a password but at 128 characters. My concern is that the salted SHA1 hash for the key has less entropy than the key ...
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What steps can you take to make offline cracking of SRP harder?

In the aftermath of the Blizzard hack, what steps can I take to make offline cracking of SRP more difficult? My question assumes that your database is already gone and that you implemented SRP more ...
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Can hash functions be used with CTR or OFB mode?

I have been writing a class that encrypts and decrypts with block ciphers. I want to use Counter Mode(CTR/CM). We know that Counter Mode generates a keystream basing on counters, then XOR the ...
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openssl_digest vs hash vs hash_hmac? Difference between SALT & HMAC?

openssl_digest vs hash vs hash_hmac I want to use SHA512 for storing password. Which of the above methods are best to use? Why? What is the difference between SALT & HMAC? I just read ...
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What about combining pkdf2 with scrypt? [duplicate]

Possible Duplicate: Would it make sense to use Bcrypt and PBKDF2 together? How does the following password hashing scheme look to you? iterations1 = scrypt iterations required to spend ...
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Bcrypt as a key derivation function?

I read a lot of entries at stack exchange about bcrypt and why it is supposed to be better than PBKDF2 in terms of password storage. I'm asking now if bcrypt is better than PBKDF2 in terms of key ...
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self-signatures using SHA1

This page says: self-signatures must not use SHA1 You can check this by doing: gpg --export-options export-minimal --export <keyid> | gpg --list-packets |grep -A 2 signature|grep ...
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Using random number to salt passwords

in a project I have, I'm salting passwords with 3 salts at the moment... Static salt - hard-coded into the source-code. Randomly generated salt (using a function designed for generating password ...
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How big is the risk of hash fixed points/cycles?

It's established wisdom to hash password multiple times with a salt to increase the time it takes per brute force iteration. At the same time (unless the algorithm guarantees otherwise) there's a ...
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Is BCrypt enough when saving a password into a database?

In order to allow users to connect to my website, I encrypt their password using BCrypt since it is one of the slowest algorithms to decrypt (making a compromised database longer to be decrypted). ...
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PHP Vulnerability May Halt Millions of Servers - max_input_vars!

Recent version of PHP 5.3.9 has been released a couple days ago, and Hash Collisions have been fixed, most of the servers actually didn't upgrade their server until now, including my website's server. ...
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Standards for CA cert revocation and time-constrained cryptographic algorithm parameters

I'm working on software that will be in use for foreseeable future (15 years+) that will need to validate XAdES-A signatures (long term archival, similar to PAdES-A, but for XML). That means, it will ...
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Why is password strength often underestimated and uncertain in the context of password hashing?

An aspect of security has bugged me for a long time: Why is there positive certainty about the importance of hashing algorithms and salts, but password strength is either never mentioned at all or ...
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Is PBKDF2 only SHA1 in C#?

I can't find a way of specifying the hashing algorithm used by the PBKDF2 (the Rfc2898DeriveBytes class) implementation in C# System.Security.Cryptography. It seems to be just SHA1. Am I missing ...
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Rainbow tables, generation and lookup, preferably using GPU

1a) What software can I use to generate my own rainbow tables, preferably software that can utilize CUDA or ATI Stream? One of the reasons I want to make my own, is that I want to use a specific ...
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Does password-hashing “busy-work” need to be cryptographically secure

All modern password hashing schemes are deliberately designed to include a huge amount of "busy-work", to limit the speed with which an attacker would be able to conduct password hashing attempts. ...
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Will my method for managing account data work?

I'm looking at whats nessecary to create a small accounts server for a video game I'm programming in my spare time. User privacy is a very important topic for me, and I don't want to keep anything ...
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Is it possible to detect password length from hash? Does doubling your password add more security?

Assuming a service doesn't store a plain text password, am I right in saying that the answer to this question depends on the service? On a bad service, the hash length is related to the password ...
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How to tell if a site is securely storing passwords? [closed]

A site I frequent has a policy to make you change your password every 90 days. That's a cool policy, but I stumbled upon an old xkcd and facepalmed myself, because lots of doxing happens on this site. ...
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Is there a table that compares hashing algorithms by speed, relatively (machine independent)

As far as I understood*, one of the major criteria when choosing a password / salt hashing algorithm is it's speed. To prevent brute force attacks, a slower algorithm is better (and also makes it more ...