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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LastPass Grid Authentication vs Google Authenticator which one is more secure?

[Being a LastPass user] recently I moved to Google Authenticator instead of using Grid Authentication as a 2-factor security. For me, finding and filling letters from such a dense matrix is a rather ...
2
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2answers
75 views

Related-password hash security

Say we are given a strong cryptographic hash function hash(), a strong completely random password of 15 characters pass15, two single-character salt values salta, saltb. We compute the hashes hasha, ...
4
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2answers
2k views

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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1answer
119 views

How does an attacker authenticate to a service using just the hash of the user (after performing a pth attack)

Let's say the attacker got the username and the password's hash. How can he use it when authenticating to some service in its domain with NTLM , for example? How can he send the request as the ...
3
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3answers
117 views

SHA and “Bits of Security”

I've researched several forms of encryption/hashing and have often come across the term "bits of security". For example, at least one source claimed SHA-256 = AES128 = ECC256 = 128 bits of security. ...
5
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4answers
5k views

Bank account number and account holder in check exposed?

I'm not sure if this is standard practice in all banking institutions but almost all banks where I've received checks the account number of the issuer is exposed (some even the account name). Isn't ...
132
votes
18answers
13k views

What is a good analogy to explain to a layman why passwords should be hashed?

Note: This is not an actual situation I'm currently in. Assume your boss is one of those old-fashioned computer-illiterate managers and wants to store the passwords in plaintext to simplify ...
1
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2answers
253 views

Hash user id securely

In my app I'm using Facebook login and creating a local user in my DB after retrieving the data. When saving the Facebook ID in the DB I need to hash it, as I don't want the ID to be in clear text if ...
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0answers
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I have litteraly no more options of how to crack this hash. PLZ HELP D: [closed]

I have found this old hash laying around and I have no idea how to crack it :P my hash: 7b62d4ef52a09bb505055296faa4ffcc I have tried everything and have come up with nadda :l I have tried brute ...
22
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6answers
18k views

Most secure password hash algorithm(s)?

What is/are currently the most cryptographically secure hashing algorithm(s)? (available in PHP) Speed is irrelevant, because I'm iterating the hash over a fixed time (rather than a fixed number of ...
-1
votes
1answer
36 views

Can I test/determine all decryption types on an unkown filetype. I do have the password [closed]

I have a file that's nearly 200Mb. It was reportedly packed/encrypted with Kruptos 2. But it has a .~enc extension. The header of the file is pure gibberish. Running file says it's data running ...
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3answers
67 views

Can I safely use my own statistics to assess password strength on number of times a password is used?

Lets assume I want to give my hypothetic 10mio users userbase a good feedback on their password strength. Besides the classical entropy tests and top500 list of bad passwords, I might want it to be ...
0
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2answers
88 views

Saving passwords decryptable for later usage

I'm in a situation where I need to calculate a hash of the result of the password in plain text plus some random chars representing a session. The gained hash will be compared to another hash that is ...
7
votes
4answers
1k views

Should the password of a password protected channel be hashed?

Let's take a chat system, where any user can create a channel with a password protection. Thus, other users may only join using the channel password. This password is therefore known to every person ...
1
vote
1answer
58 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.
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4answers
406 views

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 ...
2
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0answers
27 views

How do I verify a GPG symmetrically encrypted file? [migrated]

I created an encrypted file with symmetric encryption. gpg -c 50GBfile Now I want to delete the original. Before I delete the original, I want to verify the integrity of the encrypted file. Does ...
0
votes
2answers
72 views

How can I identify this hash? [closed]

I'm trying to decrypt my router's root password, since I only have access to a simple admin account that doesn't have root privileges. Here is the passwd file: 0:F.bCrWv/Oxp6.:0:0:root:/home:/bin/sh ...
0
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1answer
34 views

Tracking IP address to prevent abuse without logging user metadata

I am trying to balance good security practices against excessive logging of user metadata / Personally Identifiable Information. I am constructing a web app that tracks IP addresses to prevent abuse, ...
0
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2answers
54 views

What is the collision likelihood of MD5 when non-numeric values are removed?

Start with a unique identifier String macAddress = "CC:3A:61:24:D6:96"; Hash the identifier via MD5 implementation String hash = md5(macAddress); //bd37f780e10244cf28810b969559ad5b Remove all ...
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vote
2answers
336 views

How secure is the PwdHash algorithm and system?

I use the PwdHash service (http://crypto.stanford.edu/PwdHash/) and plugins for pretty much all of my passwords. I believe this is safer because: No service gets the same password as another, so if ...
27
votes
7answers
4k views

Hashing a credit card number for use as a fingerprint

What's the best way to hash a credit card number so that it can be used for fingerprinting (i.e. so that comparing two hashes will let you know if the card numbers match or not)? Edit Looking for ...
2
votes
3answers
280 views

Time Memory Trade-Off Attacks

Given, we want to crack a password. With Time Memory Trade-Off Attacks one tries to find the right balance between time to compute hashes for all possible passwords. And the used memory to store all ...
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2answers
53 views

How Empathy - a messaging program, is storing my passwords

I am connected to my chat accounts via Empathy, a messaging program, and it has my password stored in it. I am really curious to know how it is storing the passwords, and if there is any they can ...
0
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1answer
96 views

Save password on user-side for autologin

If a user wants to login to a system/server, it's recommended to have the hashed&salted password saved in a database, along with its salt. So the user wants to login, types in the password, ...
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0answers
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PBKDF2 hashing over TLS for encrptig password [closed]

i wanna use PBKDF2 hashing over TLS for encrypting password and session and that way stop hackers from breaking into my connection. How to do it in java.
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2answers
78 views

Is there any way to log in with a hash?

I've understood that the following steps are taken when I log in to a site: 1. My password is hashed 2. The hash is compared to what's stored in the database. 3. If the hashes are equal, I can log in. ...
0
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2answers
153 views

Reversible Hash Function?

Is there any reversible hash function? The hash function like SHA and MD5 are not reversible. I would like to know if there exist some reversible hash functions?
0
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2answers
75 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 ...
3
votes
1answer
103 views

A pair of 'self-signing' hashing functions?

Does a pair of (hashing) functions for which where neither g(x) nor f(x) are constants exists?
0
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2answers
119 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 // ...
8
votes
1answer
329 views

General purpose slow/unique hash routine for dup checking of private data, without storing the data itself?

I am wondering if there is a percentage of uniqueness known to be lost with every repeat of various hash routines, like MD5, SHA1, and how that might compare with other algorithms. If theoretically I ...
0
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2answers
89 views

How to generate an unpredictable but short string? [closed]

I want to built some short urls for uploaded files and links on my own server. Simple enough, I upload files and my script returns me a link. On access, the link is translated to the file and download ...
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4answers
197 views

What if I develop my own hash algorithm to create strong passwords from easy ones?

I came up with this idea but I cant figure out if it's good or bad, maybe you can help. My goal is: I want to create extremely strong passwords for my main accounts (gmail, skype and so on). I want to ...
1
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2answers
78 views

Is it unsafe to hash one password with more than one salt?

I'm asking my question here since I was not able to find an answer anywhere. I have written a piece of software which stores pretty delicate passwords. I have used BCrypt as hashing algorithm with an ...
0
votes
1answer
98 views

Advice on using encryption and hashing

I'm going to rephrase a question I asked earlier, as I don't think anyone understood what I meant. Bascially I'm writting a web based password locker, which can have multiple accounts; so that users ...
0
votes
1answer
56 views

Using encryption and hashing

I'm writing a project to securely store and share passwords between users, I've been doing tons of research into encryption algorithms, CSPRNGs, hashing algorithms, key stretching etc... I just want ...
2
votes
2answers
503 views

NTLM/LM Hashes on Domain Controller

I've noticed that when extracting password hashes from a domain controller (using Elcomsoft proactive password auditor) sometimes I'll get LM and NTLM hashes and other times I'll only get NTLM hashes. ...
2
votes
3answers
78 views

Client-side hashing of password before sending it from login form [duplicate]

I have just realized, that my web application is sending unencrypted passwords from login form. It's just like that -- I've analysed, that string sent by user from login form is hashed with MD5 (which ...
3
votes
3answers
618 views

Is this a secure way of storing passwords? [duplicate]

So a couple years ago when I was learning basic back-end web development, I found a tutorial for creating a basic log in system. I haven't done much modification to the code since, but I have the ...
1
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2answers
194 views

How to treat/hash ECDH shared secret to use as keys for AES?

I'm doing some studies/development for a security system that would use ECDH with ephemeral keys. In my code I'm currently using a 256-bit EC, so when the two parts compute the shared secret, I get a ...
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 ...
11
votes
7answers
700 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 ...
121
votes
8answers
9k views

Why are salted hashes more secure?

I know there are many discussions on salted hashes, and I understand that the purpose is to make it impossible to build a rainbow table of all possible hashes (generally up to 7 characters). My ...
3
votes
4answers
579 views

How to properly anonymize data, if hashing isn't enough?

Today there are news on Bruce Schneier's blog and ArsTechnica about how NY City released information about Cab/Taxi drivers, their trips, and so on. Basically, sensitive information was simply MD5 ...
16
votes
8answers
3k views

Won't all hashes collide after enough iterations (with a static salt)?

We all know that we're supposed to take a fairly slow hashing algorithm, salt the password, and run the hash for many iterations. Let's say that I'm following almost everything except for one rule, ...
0
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3answers
53 views

How to secure Password and Salt on a deployed application

I have a question regarding one step of protection more than salt/hash. I work on an application that is distributed to many clients and then deployed on their networks. If I set a password on one ...
0
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1answer
53 views

Using hashed password as secret key for hmac to avoid exchange of secret between server and client

I'm currently trying to improve our API to be more restful, therfore avoid any state on the server. I want to accomplish this with a hmac token, appended on every request. The hmac will be made with ...
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1answer
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I know scrypt is newer than bcrypt, but is there any reason it would be weaker?

From what I read, scrypt is (on paper) more secure than bcrypt, but it's pretty new so it's better to let it get time-tested and scrutinized first. However, is there any good, compelling reason to ...
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5answers
2k views

When hashing passwords, is it ok to use the hashed password as the salt?

I don't like this idea. But I can not come up with a technical argument against it. Can somebody explain it to me? The basic idea is: $passwd = 'foo'; $salt = hash($passwd); $finalHash = hash($passwd ...