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.

learn more… | top users | synonyms (1)

0
votes
2answers
662 views

Why can't an n-bit hash be cracked by hashing every single n-bit plaintext?

I'm wondering why it's so hard to find collisions for cryptographic hashes. Take for example a hash function that outputs a 64 bit hash. In order to find collisions, if you feed the function every ...
3
votes
2answers
229 views

Why does LastPass store password hashes on the server at all?

While reading about LastPass' breach, I was wondering why would LastPass store strengthened password hashes at all on the server side? Could they only store the AES encrypted data and when the user ...
0
votes
0answers
76 views

Hashing Identifiers to Create Pseudonyms

I'm wanting to share datasets between two organisations in a pseudonymised way such that they link together via mutual entities (e.g. people) but so that the entities cannot be identified. E.g.: ...
2
votes
3answers
4k views

Proper hash_hmac key creation

I'm looking for, but unable to find, some definitive information on how long to make the secret and what characters are useable in creating a HMAC signature in PHP using SHA256. I found some ...
3
votes
3answers
245 views

Question regarding MAC and encryption

I was reading the chosen answer to the following question - "MAC vs Encryption" They say that just using encryption, "an attacker could alter the ciphertext to make it say something else when ...
0
votes
1answer
189 views

Is this a good hash function?

unsigned int hash(bytearray[] msg) { unsigned int hash = 0xDECAFEBAD; for(i = 0; i < msg.length(); i++) { hash = ((hash << 4) XOR (hash >> 28)) XOR msg[i]; } return ...
5
votes
1answer
95 views

Salting/Hashing a password

I don't have a security background, so I'm not sure on the best approach for this, I'm developing an android app which users will need to login to (all local). I'm going to store the password in a ...
2
votes
5answers
1k views

Should BCRYPT be used for client-side password hashing

I am concerned about the use of bcrypt for client-side password generation. I am developing a password generation function to be used client-side, similar to PwdHash and PasswordMaker. Much has been ...
2
votes
2answers
90 views

which encryption is used in this JS Variables

Which encryption method is used for these variable names: var g_license_info var g_server_time_obj Respectfully encrypted to: var ago05b4e111efe149737a67a177f00ffad2 var ...
4
votes
1answer
103 views

A predictable password generator for offline clients

I know this sounds like pretty dumb question. Why would you use a password generator at all if it's predictable. But suppose you have a server and client - the server always requires a password and ...
3
votes
0answers
105 views

How far should I go in protecting a user's SMBIOS UUID?

My server will be receiving data from several hundreds of computers. As part of keeping track of which computer sent what, I will be fingerprinting the hardware and keeping the results in my database. ...
4
votes
1answer
197 views

Why is Windows password security designed this way? [duplicate]

Let's start with the LM hash. The LanMan hash had MONUMENTAL security flaws, like the password being case insensitive (converted to upper), which reduced the keyspace for a brute force attack. On top ...
3
votes
2answers
178 views

How to give “Forgot password” option for a password encrypted file?

I have created a utility that encrypts a file (.txt, .dox, so on...). The utility asks for a password from user at the time of file encryption. Problem Suppose a user has created 1000 encrypted ...
5
votes
2answers
580 views

Why not slightly modify an existing hashfunction to create your own? [duplicate]

I read this interesting question on why improvising your own Hash function out of existing hash functions is bad. However this is specifically focusing on 'mixing' existing hashfunctions. What if for ...
5
votes
3answers
169 views

How to prevent a prophecy from becoming self-fulfilling or self-defeating

Let's assume that I have deduced with a high probability what a certain famous person or organization will choose to do at a near-future date. How can I publish any proof of me having deduced this? ...
1
vote
3answers
175 views

how to authenticate user in client-server implementation

So I am trying to implement a client-server application for sending files over SSL sockets. And I am trying to decide on a very secure design for authenticating the client. The server is going to ...
-3
votes
1answer
90 views

Hash regex for malware recognition [closed]

I'm looking to store two types of hashes for recognizing blacklisted code. These are the FireEye "import hash" (or imphash) and the ssdeep "fuzzy hash". Is there a regex (or formal documentation) I ...
1
vote
1answer
161 views

best practices for storing retrievable passwords

I am trying to build a NMS (network management system) and I am required to store passwords for 3rd party databases, devices and servers that are being managed (not user passwords). These passwords ...
5
votes
1answer
168 views

Distributed tokenization for credit card numbers

I have two locations within the same firm that hold credit card numbers. I want to be able to "join" on credit card number to do business analytics after transmitting card number-linked data from one ...
2
votes
1answer
143 views

What is a key-hardened hash?

I've seen the term 'key hardened hash' used to describe a recommended way to tighten up password hashing. What does this mean? Can it just mean to use a pepper?
2
votes
2answers
122 views

Best hash for indexing and searching encrypted data

I would like to be able to do database look-ups on a set of data based on one of the encrypted fields. My understanding of the best practice for accomplishing this is to store a hash of the data I ...
5
votes
2answers
587 views

How facebook knows my new password is too similar to my old password? [duplicate]

I am still very new to Information Security field and as far as I know, websites use hashing algorithm on user's passwords before storing it and they don't know the plain-text password of a user. ...
3
votes
2answers
2k views

TrueCrypt VS LUKS Bruteforce Resilience

I have been researching LUKS vs TrueCrypt topics -- my only concern is security, but most of the discussions I see focus around usability / interoperability . I know TrueCrypt has a bunch of nice ...
2
votes
1answer
556 views

Can I know somehow if my password hash is known?

Is there a secure way to know if my password's hash is publicly known on the internet? First I tried to search for it in Hashes.org (http://hashes.org/search.php), but then I suspected, that if it ...
1
vote
1answer
43 views

Hashing Based Encryption

Let's say you take a 256 bit key and never use it to encrypt anything. You receive a message with a 16 character unique randomly generated salt pre-pended. You salt your key with the 16 character ...
-1
votes
1answer
69 views

Finding the cryptographic hashing algorithm, given the plain text and the corresponding salted hash [duplicate]

I have a salted hash (say about, 110 characters long) and the corresponding plain text that I used for hashing. As the title says, is it possible to do find the algorithm via crypt-analysis? What is ...
2
votes
1answer
148 views

How to “Pass the hash” when LM hash is disabled?

I ran the NTLM_stealer metasploit module and ended up with the following results: LMHASH:Disabled NTHASH:008940f335e9b2ddc182bb5b960a0c5bad0b125cbee3cf84 I was wondering if there is way to ...
6
votes
2answers
1k views

Does Outlook store plain-text passwords?

A long time ago when Microsoft changed my e-Mail from Hotmail to Outlook the password-interface said that I should only put in the first 16 chars of my password. But my password was longer before. So ...
0
votes
1answer
58 views

Store Hash and/or Encryption salts in database [duplicate]

I am doing a custom login for practice purposes, and i am wondering what would be the logical way to save the hashed password and the salts. Salt/Hash operations are using Rfc2898DeriveBytes class. ...
24
votes
1answer
2k views

How can the content of a file refer to its own MD5?

So I just saw this picture on Imgur: http://imgur.com/gxRCrCM The intriguing thing about it is that the picture refers to an old Daft Punk song named "Face 2 Face". The image's MD5 is ...
2
votes
3answers
307 views

Hashing passwords in OpenLDAP

I've seen a few posts on the internet saying most people store user passwords in OpenLDAP using one of OpenLDAP's many, built-in hashing functions. But OpenLDAP itself recommends handing off password ...
64
votes
11answers
9k views

Is there any way my password is hashed, if I'm only ever asked to provide 5 out of many characters? [duplicate]

There is a system that, on a login form, presents about 40 boxes for password letters (to hide password's actual length), and only random ones (the same amount each time) are editable. Explanation is ...
0
votes
2answers
128 views

Reverse engineering of hash functions

I have an unknown process that gets some vars and returns an 8byte hash. I'm sure which vars it gets and I'm sure these are all the variable parts of the input. I can query this process when and how ...
1
vote
0answers
45 views

Key stretching approaches

I've seen that a number of key stretching algorithms and they involved increasing the number of operations needed to compute the key(i.e. the number of rounds within a hash function). But, I wonder if ...
2
votes
2answers
6k views

Securing passwords for REST Authentication

I'm developing a REST application using the Spring Framework, as as part of the requirements, we have to secure the different functions of the system to different user roles (pretty standard stuff). ...
1
vote
1answer
69 views

Are multiple applications of a salted Linux MD5 hash easier to break than one? [duplicate]

I hashed the same password a lot of times (approximatively 1000 times) using the salted Linux MD5 format. I want to know if it's easier to recover the clear password or not. Is there something that ...
0
votes
1answer
49 views

Would it matter if my miner was hashing random vs incremental values?

I'm working on my miner for my "game" site that's basically a pre-image attack from a hash posted online. You submit a hash input, it's hashed, and your score is the hamming distance (the number of ...
8
votes
1answer
661 views

Why store a salt along side the hashed password? [duplicate]

Understand the need to protection credentials with hashes that are expensive and to use cryptographically random salts. What I would like to understand is why you would store the salt along side the ...
5
votes
4answers
2k views

Using password hash as session ID?

For a rich client web app, on the server I need to verify that each call comes from a legally logged in user. Obviously user ID is not enough, because that's easy to guess. I have an idea I am ...
2
votes
2answers
1k views

Is it possible to salt the SHA1 or SHA256 hash function of OpenSSL?

I would like to salt the hash function of OpenSSL external, so that I can assign a salt on my own. Is that possible or is the hash function of OpenSSL alsways internal "salted"?
5
votes
2answers
660 views

Scrypt + Bcrypt = cascade hashing [duplicate]

I've read here that hashing with differents algorithms would be a good idea. Can you confirm that? In your experience, is it useful and safe? Does it entail any security holes?
3
votes
1answer
167 views

Challenge: How to find the secret key in homebrew MAC/keyed hash: sha1(key + cookie)?

I am trying to solve a security challenge on a website. Basically, the website computes sha1(key + cookie) to sign a cookie so that the user can't change it himself, and to accomplish the goal you ...
13
votes
3answers
2k views

BCrypt's 72-character limit and using it as a general digest algorithm

Goal: have token/cookie-based authentication that doesn't require keeping sessions on the server TL;DR: What, if any, is the accepted mechanism to work around the 72-character limitation of BCrypt? ...
5
votes
1answer
2k views

What difference between AES_128_GCM and AES_128 and AES_128_CBC ciphers?

I encountered AES_128_GCM cipher, tried to find it in specifications of TLS1.2 and nothing, any mention. Could some one explain the difference between AES_128, documented AES_128_CBC and this new kid ...
15
votes
2answers
2k views

Should password reset tokens be hashed when stored in a database?

Passwords are hashed so that if someone gains access to a database of passwords then they won't know what the actual passwords are and so they can't log in. If I can get a valid password reset token ...
2
votes
3answers
1k views

Strategy for updating stored passwords to more secure hash? [duplicate]

I know that we cannot update our hashed passwords without having the plain text password to re-hash. When a member logs in with login/password, we have the plain text, so that gives us an opportunity ...
5
votes
1answer
2k views

How can a system verify an online password using a phone keypad?

I phoned into a financial company's website, and it prompted me to key in my password on the phone keypad, converting the alphabetic characters to the corresponding digit, and special symbols to '*'. ...
9
votes
2answers
627 views

How to store/encrypt fingerprint?

Storing password is a no brainer : use a password hasher. But.. How do you proceed to store fingerprints securely on your server? Meaning that even if your server and all it's data is stolen, someone ...
0
votes
1answer
1k views

Extract Password Hashes from Active Directory LDAP

Currently we are working on a monthly internal security test which among other should contain a verification of the real password strength the users choose. For this reason I want to extract the ...
0
votes
0answers
32 views

Password storing using hashing only, encryption plus hash [duplicate]

I want to hash password before storing to database. I am not able to understand which approach will be suitable.For examples Hash plain password directly with SHA-1, SHA-256 etc and then store in DB. ...