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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11
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7answers
831 views

Aren't password managers still incredibly risky?

I understand the utility in having one application remember a bunch of long, randomized passwords, but all you'd need is one well-placed phishing scam or a keylogger and they get all the keys to the ...
1
vote
1answer
649 views

Cracking MD5 passwords with the same salt

How long would it take to crack passwords up to 10 letters long if you knew the hashes were MD5 with a salt (that you know)?
2
votes
2answers
111 views

Breach informing

I am a staff member of a large fanfic site, but not the head administrator with control over the site itself. Recently, we had a security breach and the databases were copied, which included the ...
4
votes
3answers
241 views

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. ...
8
votes
3answers
4k views

How often do two users use the same password

If no two users use the same password, then in theory salting the password hash is not needed. How often, in practice, do two users have the same password?
70
votes
8answers
9k views

Convincing my manager to use salts

My manager says we don't need to salt our passwords because people are not likely to use the same password because they all have different native languages, in addition to the websites they are active ...
1
vote
1answer
106 views

Ldap differences between {crypt} and {CRYPT}

I recently stumbled upon some password entries in LDAP marked with the {crypt} scheme. Since all recent entries are {CRYPT}, I was wondering what the differences between the hash algorithms are.
0
votes
2answers
242 views

Storing multiple hashes to prevent collisions, security risk?

This is all just for curiosity's sake, so discussion on which hashing algorithm is harder/better/faster/stronger is irrelevant. But my question/thought is this.. With regards to password storage, and ...
1
vote
1answer
154 views

Theoretical home grown password options, or what is it that SCrypt, BCrypt, PBKDF2 does that is so special?

I'm developing a personal web framework, nothing internetty, and probably not even anything that will ever go on my personal LAN. And looking for password advice people seem to only recommend those ...
42
votes
5answers
4k views

Is it safe to tell your users what kind of hashing algorithm you use?

For example, on the user registration page, is it safe to tell people "Your password will be stored as a one-way hash using the (whatever) algorithm."
-1
votes
4answers
236 views

Is salted MD5 or salted SHA considered secure?

Is using something like bcrypt or scrypt necessary? The hashes are so much longer to store in a database. Can one get away with using salted MD5 or SHA and still be secure?
1
vote
4answers
186 views

Hashing Email Address and Contacting User

I am thinking about a log-in web service that would store a users username, password, and (optional) email address. If they forget their username or password, they can have their username and a ...
0
votes
2answers
106 views

Is a long salt usually sufficient for security purposes, even with MD5?

I always hear that MD5 is too fast for effective password crypto because you can crack up to 6 characters very quickly (or is this number higher now)? But what if the salt you use is really long and ...
0
votes
2answers
78 views

Why RSA signatures based on the hash of the message? [closed]

Why RSA signatures based on the hash of the message rather than the message itself?
2
votes
2answers
544 views

Protecting hidden form fields

The scenario is as follows: An application has a web interface through which data can be configured. The data to consider for this question is Users with a many-to-many relationship with Groups. ...
1
vote
1answer
86 views

Log file checksums

I am told that you can tell if the log file (like from ripping a CD) has been modified by its checksum. How? How do you bypass this if you wanted to modify it?
2
votes
1answer
77 views

Identical lanman hashes on AD accounts?

I ran metasploit's smart_hashdump module against my (2008r2) domain controllers, trying to find any accounts that may still have lanman hashes in place. These should have been disabled long ago. I'm ...
1
vote
1answer
137 views

What are the enhancements of SHA1 compared to MD5?

I am looking for enhancements of SHA1 when its compared to MD5. But I am not talking about just heap sizes. I am talking about different enhancements than heap size. Also, I think md5 is faster than ...
0
votes
2answers
83 views

Security of this account login system

I have an idea to implement a account system using email and passwords for games. Im intending to have the account creation and forget password systems on a webpage. So if users will have to access ...
1
vote
2answers
103 views

Can I save & store a user's data in a way that proves that the information has not been altered, and that the timestamp is accurate?

There are many situations where the validity of the timestamp attached to a certain post (submission of information) might be invaluable for the post owner's legal usage. I'm not looking for a service ...
1
vote
2answers
62 views

A manual function for hasing identity?

I hope you won't close the question. Even though there are no computers involved, it is still about information and security, and I think that security experts are the ones who will be able to help ...
0
votes
2answers
139 views

Why do file storage sites have a long unique id for their download links?

I'm creating a file storage site and what I would do is just have the download links format as: https://www.domain.com/[id]/[file name] //id would just be 1, 2, 3 etc. Dropbox and many others have ...
0
votes
4answers
1k views

What are the advantages/disadvatages of hashing over encryption?

I know that hashing is a one way function and encrypted messages could be retrieved if you know the corresponding key to which you encrypted the message. Other than the ability to retrieve, what ...
1
vote
1answer
94 views

Algorithm to Transaction Data Signing

Transaction Data Signing I need an idea to develop a very secure algorithm to authenticate online operations using PHP in the server and an Android app in the user's device. What is the idea? The ...
2
votes
2answers
572 views

Content-Security-Policy hash of script

<?php header("Content-Security-Policy: default-src 'sha256-".base64_encode(hash('sha256', 'console.log("Hello world");', true))."'"); ?> <script>console.log("Hello world");</script> ...
4
votes
1answer
68 views

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 ...
1
vote
3answers
264 views

What part of the CSR is hashed in order to create its signature?

I'd like to change the CSR before it is transferred to the CA without going through the CSR creation process again. To do that I need to know how to calculate the signature of the CSR after I modified ...
15
votes
2answers
581 views

Can client-side hashing reduce the denial-of-service risk with slow hashes?

When storing user's passwords that you need to verify against (but not use as plaintext) the current state of the art is: Hash the password Use a salt Use a slow hash function - bcrypt, scrypt, etc. ...
2
votes
1answer
195 views

Any reason I shouldn't be salting and hashing before putting through bCrypt?

I've been reading up on password storage and such, and have come to the conclusion that I need to be using bCrypt. I've got an implementation working correctly, but I'm wondering the best way to move ...
0
votes
1answer
61 views

Find hash-function if original and hash are given? [duplicate]

I was thinking whether or not you can find the hash function(s) used if you have the original message and the hash. So assume that no salt is used during the hashing process, just multiple hashing and ...
1
vote
1answer
294 views

How do we estimate the time taken to crack a hash using brute force techniques

A German hacker famously managed to brute force crack a 160 bit SHA1 hash with passwords between 1 to 6 digits in 49 minutes. Now keeping everything constant (hardware, cracking technique - here ...
-1
votes
1answer
105 views

Hash leaked online

Recently I Googled the email address of one of my friends, as I was just curious of what would come up. Lo and behold, he saw what presumably is his Gmail hash. It is part of a list of 10,170 email ...
0
votes
0answers
32 views

Hashing / How easy is it to infer the original input if the a slight variation of the input, the hash result and the hashing algorithms are known [duplicate]

Given that I have an initial input that is publicly known (e.g. "ABCDEFGHIJ") a slight variation of (1) (e.g. "BACDEFGHIJ") that is used as the input to a hashing algorithm (3) an modern one-way ...
2
votes
1answer
116 views

Stream/Block encryption using XOR and Hash function?

Could a hash function like sha1 or ripemd-160 be used for secure key generation in a stream/block cipher? Obviously a repeated key like "abc123abc123abc123" would be bad, and a one time key pad would ...
1
vote
1answer
157 views

Challenge-response login without storing a password equivalent

A problem with many challenge-response login systems is that the server has to store a password equivalent. For example, if the server stores SHA1(salt + password), and an attacker captures that hash, ...
3
votes
4answers
650 views

Can I brute-force a password hash even if I don't know the hash-algorithm used?

Can I brute-force a password hash even if I don't know the underlying algorithm? For example if I get hold of a database with password hashes and the used hash algorithm is unknown, like a random ...
3
votes
2answers
213 views

MySQL ENCRYPT salt is not random?

I know there's little reason to still use ENCRYPT() nowadays, what with bcrypt being almost ubiquitous and MySQL providing better hashes such as SHA1. But while dabbling with ENCRYPT() on MySQL ...
0
votes
2answers
256 views

Is there any issue using the PHP crypt() function with an additional salt?

Is my PHP authentication script secure? I noticed that the hashes start with the first two letters of the username. Could there be a security flaw using crypt() in such a way? <?php // ...
1
vote
1answer
469 views

How to identify hashing algorithm [closed]

I want to identify the hash algorithm used by an online service. What I have now is thousands of pairs of original string and result hash. Some examples: 62.152.39.195 25d10817d8d2836925 ...
3
votes
4answers
143 views

Record IP pseudonymously?

I'd like to be able to ban an IP from my website, but for privacy reasons I would like to not have a record of the IP itself. Hashing the IP would allow for the hash to be brute forced in mere ...
0
votes
1answer
77 views

In IKE protocol; what is the PRF? [duplicate]

In IKE protocol; what is the PRF ? What is "the generation of a key based on modeled random oracle hash functions"?
2
votes
1answer
154 views

PRF, IKE and hash function

The term PRF is mentioned in the documentation of the IKE (Internet Key Exchange) protocol. What is a PRF? What is the difference between a PRF and a hash function? What PRFs are used in the IKE ...
-3
votes
2answers
501 views

Can NSA generate all hashes for rainbow table to break md5?

I was wondering about md5 encryption. It is good, and I agree that it is unbreakable. But this is why we have rainbow tables. What if bunch of people gather together and start brute forcing and ...
3
votes
2answers
1k views

Is it a good idea to store Email addresses as hash only?

I am currently building a web service at http://write-math.com similar to http://detexify.kirelabs.org/ that should help users to get LaTeX code from drawn formulae. It is part of my bachelors thesis ...
0
votes
2answers
139 views

Asymmetric Data Storage+ No-Hash Password Storage?

Edit: removed a part of the original question; I'll break it down in a different post. I am following @Polynomial's answer to store information in a database. Here are my requirements: Only the ...
1
vote
1answer
2k views

Cracking Mysql 5 Hash using Hashcat

I am practicing cracking MYSQL5 hash using hash cat, however, for a reason or another, it finishes the cracking process too fast -within 30 seconds- without giving any results/errors back. I doubted ...
2
votes
3answers
552 views

Hashing speed with true random passwords

Just a theoretical question: If I had ideal users, who all provide fully random 128-bit passwords, And also, I invalidate every password shorter than 128 bits. Then would I still need a slow hash ...
2
votes
1answer
159 views

Hashed passwords for NTLM authentication

I understood that Windows users' password hashes can be exported very easily. Right? So my question is: If I can have the hashes of other user accounts (e.g. local users on my Windows machine), isn't ...
9
votes
5answers
2k views

Whenever an unhandled exception somehow makes it into production, is it safe, viable, etc. to print an encrypted stack trace to the end user?

Whenever an unhandled exception makes it into production somehow - whatever the reason - there's generally an option (especially with .NET programs) to print out a stack trace to the end user before ...
9
votes
6answers
2k views

Should I hash a password if it is randomly generated

The best practice is we should hash a user password using algorithms such as bcrpyt to protect the user, however, given the following conditions, is hashing in the backend still matters? the ...