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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Is Using MD5 Sufficient Reason to Reject This Payment Processor?

I'm evaluating a credit card processor[1], and I noticed they are using MD5 as part of a salted hash algorithm to protect a secret key. Since I know MD5 is generally considered broken, this feels like ...
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Salt placement prior to one-way hash

In one-way hashing its common to prepend or append the salt to the secret and then hash it: (salt + secret) or (secret + salt). I was thinking of this metaphor as salt falling on a plate of food. It ...
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Does the md5 (or any hash for that matter) of a string include the null terminator?

Does the md5 (or any hash for that matter) of a string include the null terminator in its calculations? That is does the hash of a string equal the hash of the sequence of bytes that represents the ...
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Identifying an unknown hash

During some of my research work I encountered an unknown hashed string. What I am curious about is the algorithm used to generate it. A factor that makes it interesting - the string contains an ...
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How to crack password hashed using SSHA?

Is it possible to crack a password hashed using SSHA if I know the salt? How can I do it?
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604 views

Is it a good idea to have a “master” password?

Though I do have a good memory of passwords, it is quite impossible to have one password per application. Yet, it should be... My current way to deal with passwords is to have five passwords and to ...
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664 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 ...
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2k views

New to security, is php password_hash() good enough?

This is the first time I've had to handle personnel information and I want to make sure I have a good amount of security. I will be storing users' emails and passwords for their accounts on a MySQL ...
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795 views

How should I choose a difficulty factor for my password hashing function?

Assuming that I'm doing password hashing properly and using bcrypt, scrypt or PBKDF2, how should I go about choosing an appropriate difficulty factor? i.e rounds for bcrypt, iterations for PBKDF2 and ...
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274 views

Encrypting short identifiers?

I am developing a webapp that does not reveal record count, because it hides the primary key. I am looking for a better way to do this. My favorite idea is to encrypt the ID itself with a block ...
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Keeping user data private in a cloud environment like Google App Engine

I am writing an open-source Java application for Google App Engine (GAE). The application will let users create content that is intended to be private. I want to provide reasonable assurances that ...
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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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Techniques to make a login page safe without using SSL

I am developing a web page where people can write and comment things (no personal informations required) and I need to put a log in form so users can see all their actions on my web page. My idea is ...
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What is the best way of securing a website logon without SSL or preshared keys?

Today I sniffed some unencrypted wlan traffic during class and I found quite a few passwords by a simple search for "pass" and "user" in wireshark. Turns out about half the sites we use for school ...
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Does truncating the cryptographic hash make it impossible to crack?

I store password hashes in their full value for example, $h = sha256('foo') outputs 64 characters: 2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae I store that directly in the ...
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642 views

Are online hash calculators dangerous?

I was about to use an online MD5 checksum calculator when I realized that my result could be added to a database. This is significant because the string I was going to type in was my bank password. ...
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403 views

How can Microsoft validate a shorter password on Microsoft accounts (MSDN)?

I recently ran across this when logging into MSDN. (I saw this screen after typing my initial credentials.) I have a 20+ digit password, however there's apparently a new requirement for Microsoft ...
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SHA, RSA and the relation between them

SHA is the hashing mechanism. However, RSA is the encryption algorithm. So does RSA algorithm use SHA hashing mechanism to generate hashing keys which in turn is used to encrypt the message?? ...
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Is it better to hash n*x times in sha1 or n times in sha512 on the client side?

I already know I"m going to hash the user's password n times in either sha512 or n*x in sha1 before it is sent to the server. Once at the server, I'm going to use bcrypt set to use ~1/100th of a ...
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Patient Hashes for Compression and Security

Are there any front-running approaches to using server-generated hashes to encapsulate patient condition in a concise manner while maximizing security? For example, a system to represent current med ...
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2k views

What algorithms are best be cracked by GPU?

What algorithms are best being attacked by a GPU powered password cracker? For example, I heard that md5crypt that is being used in unix shadow file, is not the best choice for GPU cracking because it ...
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271 views

Would secure storing of past used/generated passwords be a good idea?

Let's assume an organisation that generates ~100 Passwords a week; these Passwords are 32-Characters long and randomly generated. The consultants that need passwords generated use a Password-generator ...
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165 views

Is it safe to store hashes of possibly non-existing passwords in a less safe way?

I would like to implement a lockout mechanism that not only protects against same username and many passwords attacks, but many usernames and same password attacks too. To implement this I figured I ...
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599 views

What is “c/s” in context of hash cracking?

I was reading hashcat's About page, and the stats are listed in terms of c/s....is that "Cracks per seconds"....the 'c' part seems wrong, I'm just guessing. What is 'c'?
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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 ...
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849 views

Global check of input/output of known hash functions

Is there a website, application, or script that will allow you to give an input/output for a hash function, run these against known functions, and return any matches? Here's one attempt to list the ...
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How do I use Skein's Stream Cipher?

I understand the NIST hash function competition candidate Skein comes with a built-in block cipher, Threefish, that is turned into a stream cipher by using Unique Block Iteration chaining (is that ...
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281 views

Calculating password hashes in the browser?

I just finally got into Keybase and was surprised to see this in the sign-up page: Shouldn't password stretching and hashing be done on the serverside, as we normally don't trust a client?
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Should we start using SHA-3? [duplicate]

Possible Duplicate: What is SHA-3 and why did we change it? SHA-3 has been finalized! So, what does secuirty.se think about the new hash funciton? Should we start replacing all uses of ...
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chosen plaintext attacks against MD5 and SHA1

According to http://tools.ietf.org/html/rfc2617#section-4.9, having the server chose a nonce but not having the client chose a nonce opens up Digest Access authentication to chosen plaintext attacks. ...
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Truncating the output of SHA256 to 128 bits

suppose we need/prefer 128 bit hash output. for example to generate a 128 bit encryption key or, in other applications (e.g. file integrity verifications), to consume less storage space. i don't know ...
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972 views

NTLMv2 resistance to bruteforcing

I have a question regarding NTLMv2 resistance to password bruteforcing. I know that some modern graphic processors (like Radeon 6990) are able to calculate billions hashes per second and crack NTLM ...
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905 views

Reducing password length with hash function

Suppose I would like to use a very long string as a password. As an example we can just say this string is 100 characters in length. However, suppose the application for which I would like to use ...
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Implementing Secure Remote Password: Constructing the verifier

The SRP protocol as described in RFC 2945 generates the password verifier: x = SHA(<salt> | SHA(<username> | ":" | <raw password>))` v = g^x % N I have three questions: why use ...
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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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How could one detect if Apple/Google/etc. has modified a third party application distributed through their App Stores?

Are there any realistic methods for verifying that Apple or whoever has not tampered with third party application distributed through their App Store? You might for example have an open source ...
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770 views

Secure authentication: partial client-side key stretching… please review/criticize my idea

I am trying to figure out what would be the 'perfect' authentication system for a website. On one end, we know that simple hashing algorithms can be brute-forced or cracked in other ways. Hence why ...
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Is every hash format that nginx accepts for HTTP Basic Auth weak against brute force?

According to http://nginx.org/en/docs/http/ngx_http_auth_basic_module.html nginx can read password hashes of these types: crypt(), apr1, SHA1 & SSHA. This is how I understand how these hashes ...
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Production ready bcrypt implementation for .NET

Which, if any, .NET / C# bcrypt implementations are considered suitable for production environments? I have seen CryptSharp and BCrypt.Net mentioned in answers to other questions but without any ...
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Is it a good idea to use an input by the user as SALT?

I have read many Q&As here on IT Security about password hashing and salting. I am building a simple registration form for our community website which will be used by our members to create their ...
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554 views

Does it make any sense to alter a hashed password? [duplicate]

I've always wondered if it would make any sense to put fake characters into a hashed password? For example this is my password: 1234 and after hashing the password , this is the result: abcd Then ...
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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 ...
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726 views

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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Brute force vs other methods of recovering passwords from shadow file

Do you know any good approach for de-hashing/actually bruteforcing hashed passwords in the shadow file? On various operating systems, any good solutions/methods/programs. Or is it better to upload ...
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183 views

Is hashing a string a secure manner for generating passwords?

I have several servers that I'm using for an online business. I have passwords for MySQL, Wordpress, SSH, FTP, Domain Provider, Paypal, and many more. I wanted to have a different, very long password ...
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Is it safe to use different derived keys but from the same passphrase for AES CBC encryption followed by HMAC SHA256 hashing?

I am working on a cross platform (JS/iOS/Android) list manager application that persists data through a REST API and I want to ensure that any textual data is properly encrypted on the client side so ...
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mathematically / theoretically, what is the chance that 2 different inputs would have the same results of 2 different hash functions?

mathematically / theoretically, what is the chance that 2 different inputs would have the same results of 2 different hash functions? As an example, i will use 2 weaker hash algorithms, the MD5 ...
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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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625 views

Trying to understand password hashing

I am trying to get a grasp of password hashing. Back in the days it seemed so simple, just MD5(password + salt) and you are done. Then md5 was proven to have collisions so people started moving to ...
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Does checking the fingerprint of a self signed certificate improve security?

I am currently developing a component for an application that does TCP communication with a device inside a local area network. I use TLS to provide data encryption, integration and authorisation. ...