Questions tagged [bcrypt]

bcrypt is an intentionally slow hash algorithm specially designed for passwords.

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Combining algorithms for password storage?

Is it more secure to combine algorithms for password hashing, for example, Scrypt, Bcrypt, SHA-3, etc.? If an attacker wants to use dedicated hardware, he would need one for each algorithm. However, I ...
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Why can't one implement bcrypt in Cuda?

I had heard that although it's easy to implement message digest functions like MD5, SHA-1, SHA-256 etc. in CUDA (or any other GPU platform), it is impossible to implement bcrypt there. bcrypt is ...
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Storing passwords in a publicly available database

I have a public database where users need to store configuration files. The file can contain passwords. Everyone can read config files but only the server can read passwords in them. In the browser, ...
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Why do I need to store the salt for generated hashes?

I am new to crypto and authentication so have been doing reading around this and thought that I had a pretty good understanding of how this works. However when implementing my hashing using ...
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Looking at hash output – is Base64 encoding in any way better than HEX encoding?

I was wondering why most "normal/unsafe" crypto hashes like SHA-256, SHA-512, Whirlpool, RipeMD-160, MD5, etc. are HEX encoded. But most "secure" crypto hashes (KDF' ) like ...
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enhanced hash password in bcrypt for nuGet library

Why do we use EnhancedHashPassword in nuGet library and chose a SHA algorithm like this? ...
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migrate bcrypt -> argon2

We want to migrate our userbase from bcrypt to argon2. I was planning on an approach that migrates all hashes immediately to argon2; "old" users would have an argon2'd hash of their bcrypt hash of ...
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Password hashing security of argon2 versus bcrypt/PBKDF2?

I wonder if it can be approximated how much of a security margin the new argon2 hash, winner of the password hashing competition, can give over bcrypt or PBKDF2, for an attacker using large GPU ...
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Add a pepper to a hash: as a string or a buffer, and should I calculate a hash of a peppered plain text?

I'm using a bcryptjs to generate a computationally slow hash function for storing passwords: ...
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Is bcrypt better than GnuPG's iterated+salted hashing method?

GnuPG has slow hash built-in in form of iterated+salted S2K. Does it have disadvantages in comparison with bcrypt or scrypt? Is GnuPG's slow hash method easily automated in GPUs?
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20 bytes random string hashed with unsalted bcrypt or scrypt?

I have users for which I use a SHA-1 hash as an API key. These are urandom feed into SHA-1 so you can assume they're fully random. There is no username sent along with the API key. I don't want to ...
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Why authors of bcrypt have chosen blowfish and not some hash function like SHA-1?

I wonder what are the advantages of using bcrypt over an iterated and salted KDF based on some cryptographic hash function like SHA-1 (or SHA-3)? I guess the authors of bcrypt chose Blowfish (a block ...
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Identifying the exact encryption procedure by database hash

I was asked to develop an external user administration for a legacy system so that it could be integrated into company processes. This system is mostly written in Python, but also uses unmanaged DLLs. ...
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Which is more secure, using just bcrypt or SRP?

OK, here's the two different ways I was thinking about making the authentication for the login thing to store the passwords securely. The first is the following. Client hashes password bcrypt(...
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“Work factor” and “iteration count” nomenclature in adaptive functions

In adaptive functions like PBKDF2 / bcrypt I often read people refer to "iteration count" and others refer to "work factor", and they seem to be used interchangeably (even though they're not - the ...
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Why is Bcrypt called a Key Derivation Function?

I am trying to understand why is bcrypt called a Key Derivation Function? I looked up the details of Ekfblowfish on Usenix article. After reading it, I understood that: The password is the ...
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XOR Encryption with bcrypt password de-biasing

Objective: To have a very simple to verify, but very secure small message encryption. Idea: Message ⊕ bcrypt( Password). We remove password biases with bcrypt ...
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Which is more secure for hashing: SHA512 or BCrypt with the same salt reused over and over?

Setting aside questions of if BCrypt should even be used in this way, I was just wondering which one would be more secure hypothetically. If you want to know why I don't just use random salts as per ...
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reusing blowfish algorithm to implement bcrypt

I'm trying to implement bcrypt and have a really fast Blowfish implementation available to me. It seems to me that the existant Blowfish implementation is not going to be able to be leveraged to ...
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Is It Safe to Reuse the Same Salt in Bcrypt Password Hash (Specifically for Chaining Hashes)

As explained in my previous question, I want to develop a scheme which would be able to increase the password hash strength without the user password. According to Thomas Pornin it should be safe to ...
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Are there any known security issues when doing the following chaining of BCrypt Hashes: 'bcryt(bcrypt(user-pw, work-factor1), work-factor2)'

I am currently developing a protocol which would be able to "upgrade" the strength of a bcrypt password hashes without the knowledge of the user-password so a system may upgrade it without user ...
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Why does PHP crypt give this unexpected result [closed]

So I have this PHP code,it is meant to encrypt a users password... Three problems/questions: My 'salt' CHANGES ITS NAME I get the same result Is this actually how the result is meant to be? PHP CODE ...
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Hashing user password without database to store salt

I am building an Android app that will run purely locally on the user's device, no servers. It has a database that I want to encrypt with the user's password, which requires a 64 byte key. I've ...
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Set/change password functionality on password: should I apply bcrypt server- or client-side?

I am writing a webpage on which a user can set (when registering) and change his/her password. This page is only served over HTTPS. When the user is altering his/her password, he/she is already ...
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bcrypt - collision-resistance against chosen salt and work factor?

Would it be difficult to find (cost, salt, input, password0, password1) such that ...
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511 views

If and why is it bad to scrypt a bcrypted password?

This has been already brought up on security SE, but very sadly, this particular interesting issue got watered down in a far broader question. If and why is it bad to use the following hashing ...
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How do I verify a reset token if the token is hashed in DB?

I've been searching around the web for best practice how-to on secure password reset system (email with reset url), and the idea to hash the token in the database, which I did not implement at first, ...
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Are there any known values for common hashes known to have no preimage

In a system which requires a user to have a password, as a quick workaround I wrote random junk as the bcrypt hash so that no one will be able to login to that user. However theoretically there ...
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Practical BCrypt plus XOR encryption for small messages

This is a practical solution available and potentially useful to everyone, so please give some leeway not banning this question. Details are at the end, but here is the question: How secure is the ...
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What is best practise for salting and multiple-hashing of passwords?

I have been presented with some custom PHP code for salting passwords and applying multiple rounds of hashing. It looks reasonable, but I fear home-grown crypto. Is there an existing password ...
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Is there a way to use bcrypt with passwords longer than 72 bytes securely?

From my understanding BCrypt truncates the password to 72 bytes. If a password is longer than 72 bytes, what is a way to store that password using bcrypt securely without compromising it? Or is this ...
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Unable to implement Client and Server Side Hashing (Validation problem)

I'm trying to implement hashing on both client and server Sides for my web/mobile Application. On the client side, I implemented the slow hashing algorithm (bcrypt) On the server side, I tried to use ...
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Can multiple hashing weaken the password?

Problem. I want a longer key out of password than my hashing function provide. Idea. I want to hash password multiple times rotating chars one position each time and use composite key. Question. ...
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Can pbkdf2 be used with a fixed salt to give a deterministic slow hash?

I need a password hashing function that is deterministic. Correlation attacks are not a concern. The same password must produce the same hash. I just want to protect the password against dictionary ...
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Relation between encryption algorithms and (password) hash functions

This is a really basic question. Blowfish is not seen as a secure cipher. but bcrypt is one of the most secure hash functions. So first: How can a hash function be based on an encryption algorithm, ...
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Benchmark differences between SHA-512 and bcrypt

So I recently made a benchmark SHA-512 vs bcrypt with hashcat CUDA. Here are the results : ...
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Question about hashing passwords with PBKDF2

I am new here and new to encrypting and securing passwords, so please forgive me if this question is not posted to the right location or if my question is bad. I have been working on a web app in ...
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Encrypting bcrypt hashes

I've been asked by a client to give some advice on hashing and as it isn't my area I'm looking for someone who knows what they are talking about. The client is hashing 4-6 digit PINs (mostly 4 digit) ...
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What impact could general quantum computing have on BCrypt?

While discussing the 72 character limit of BCrypt, the question of resilience to quantum cryptanalysis came up. A search online didn't give me much of a lead as to what research has been done in this ...
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Dropbox Password security

Dropbox have recently published How Dropbox securely stores your passwords Is this really more secure than using bcrypt with a complexity of 11 or 12 ? The password "chain" is secure as its weakest ...
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Why bcrypt is one-way while Blowfish is reversible?

While bcrypt is often regarded as an irreversible hashing function, it's based on the reversible Blowfish cipher. I'm just curious about how does this work. Here's ...
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How can I accomplish Key Derivation in JavaScript? [closed]

I need to take a potentially weak user password and derive a strong key for AES encryption in JavaScript. How can I do this? I expect the hardest problem is generating a good random salt - perhaps an ...
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anything obviously wrong with my custom password hash scheme?

i sha2-256 hash the password, then i base64 encode the hash (per RFC 2045) , resulting in a 44 bytes string looking like LPJNul+wow4m6DsqxbninhsWHlwfp0JecwQzYpOLmCQ=...
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Public SRP verifiers or public hash chain “public keys” when secret is low entropy password

I want to set up the following: An untrusted server should host user sessions and authenticate users without knowing their passwords or being capable of creating a fake user session in the user's ...
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Can one efficiently iterate valid bcrypt hash output values?

bcrypt is an intentionally slow hash algorithm. In my last protocol idea, I wanted to use it to expand a password and then only transfer the bcrypt-hashed password. An efficient attack on this would ...
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Using bcrypt for MAC - is it correct and secure?

Suppose there is a hashing function: $$ph = bcrypt(sha256(m + k), salt)$$ Here $ph$ is a password hash obtaining by applying $bcrypt$ on $sha256$ result of concatenating a message $m$ with a secret ...
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Does a big salt have the same memory effects as Bcrypt?

Citing Thomas Pornin on the question Why can't one implement bcrypt in Cuda?: bcrypt is a variant of the Blowfish key scheduling, which is defined over a table (a few kilobytes) which is constantly ...
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The internals of bcrypt

I'm attempting to get a better understanding of cryptography and have run into some questions about bcrypt. Bcrypt relies on the blowfish cipher, which is a reversible method of encryption. But ...
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Some questions about the internals of bcrypt [duplicate]

I'm attempting to get a better understanding of cryptography and have run into some questions about bcrypt. Bcrypt relies on the blowfish cipher, which is a reversible method of encryption. But ...
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Why does 0x00 make bcrypt weaker?

On the following site: https://paragonie.com/blog/2015/04/secure-authentication-php-with-long-term-persistence when talking about the dangers of using bcrypt it states: There is a nontrivial ...