Questions tagged [salt]

Salt is unique (usually random) data passed into a hash function for password storage to avoid the possible usage of rainbow tables or similar attacks. Salt will not help against dictionary or brute force attacks, as the salt is usually stored together with the hash.

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470 views

Is the seed/salt input of a Key Derivation Function confidential?

I'm implementing a security protocol and for the key management a scheme is proposed using a key derivation function on the remote device. Thereby the input seed is uploaded in plaintext to the remote ...
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976 views

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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How do you get the original salt after it's been hashed to the user's password in the database?

I'm researching how to do salt and hashing. I'll be using SHA256. Here is what I found: To Store a Password Generate a long random salt using a CSPRNG. Prepend the salt to the password ...
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Salt for non stored passwords

I read a lot about the concept of adding a salt to a password and understand that it protects against rainbow table etc. attacks. But this kind of attacks are based on getting access to the server ...
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Is it safe to re-use the salt for HKDF as a challenge for proof of possession after key derivation?

I have a system made of 2 or more parties, already sharing a master key MK, who want to agree on a session key SK (both 128-bit ...
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Why it seems to me common to say that a hash salt is “random”?

I'm not a cryptography expert. In this video, and in some other places in the web, I saw hash salts are being called "random". But if the salt is created only once and then reused each time anew, ...
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How come hash salt doesn't make a hash ineffective?

I am not a cryptography expert. I watched this video regarding hashing and salting as part of the course User Authentication With Express and Mongo in teamtreehouse.com. I understand from the video ...
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2answers
1k views

About salted passwords

In most applications, all passwords are salted independently. In terms of security (e.g. attack complexity), what are the consequences of the following differents approaches: All passwords are salted ...
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Some Questions about salts

I am an amateur teaching myself, so please don't expect too much professional knowledge. I have some things that are not clear to me about salts. For example I wondered if a "too strong" salt could ...
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Proper number of salt bytes for Rfc2898DeriveBytes/PBKDF2

I know that .NET's Rfc2898DeriveBytes requires at least 8 bytes of salt, but how many bytes are ideal? When a user is created, or changes their password, my server stores a new random salt for that ...
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Is it a good or bad idea to include a password's salt in the calculation of a MAC?

Say there's a cryptosystem where encryption and authentication of data is done using a key derived from a user-given password using something like PBKDF2. Is it a good or bad idea to include the ...
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Do I need to worry about the IV if I use a 32 byte random salt with SCrypt and AES-GCM?

I am encrypting a DEK (data encryption key) with a KEK (key encryption key). The KEK is generated from a password using scrypt with default parameters and a 32 byte randomly generated salt. The ...
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Question about IV/initialization vectors

I found some code to get crypto-js to encrypt data in the browser, and with a pointer from someone on SO, it now decodes data as well. My next question is about the use of an IV; is an IV like a salt ...
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extract password hashed in scrypt using hash and salt [closed]

I have the hashed password and its salt. It is encrypted using SCRYPT by firebase. How can I extract the plain text password from these two? Or alternatively, how can I re-encrypt or convert them ...
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How do I create an effective salt?

Background I have recently started to get into web development and thus I have been creating databases for users. After some research, I discovered that password encryption is not password hashing. ...
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430 views

How to calculate the needed encryptions in salted passwords?

Consider if a 16-bit salt is used, and it is uniformly applied over a very large password file (200,000 entries). An attacker wants to see if one particular password (say, "bubba") is used by any of ...
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1answer
36 views

Reusing characters from plaintext in salt

I'm curious about the security implications of reusing characters from the plaintext as salt.e.g. $salted_plaintext = $plaintext[1] . $plaintext[7] . $plaintext; ...
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1answer
783 views

storing salt in app

I want to create a key for my realm database wich work with AES-256 and for encryption wants a byte[64] key. I read this good question about create a key from 4 ...
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Risk of appending secret salt to plaintext prior to RSA encryption?

TL;DR Will appending session id to a password prior an RSA encryption introduce vulnerability where an eavesdropper can collect multiple encrypted password ciphertext and perform cryptanalysis to ...
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How long should the salt be for PBKDF2?

In order to complicate rainbow table attacks, salt must be provided as input to PBKDF2 when a key is derived from a low-entropy password. I have decided on my algorithms and key lengths to achieve ...
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Authentication of short message based on 6-digit alphanumeric compare-and-confirm

I have two parties that want to communicate with each other based on a shared password. The protocol is using PBKDF2 (with HMAC-SHA256) to create a shared key on both sides (due to restrictions on the ...
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2answers
448 views

Usage of “Salt”

Can somebody explain how Salts should be stored in the database? How is the process of using Salt? I've read in a book that the Salt should be stored next to the hash table database. But what happens ...
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1answer
956 views

PBKDF2 without salt on 16 digit password

How secure would be to use PBKDF2 without salt (or with the same salt for all) with a 16 digits passwords that are unique and randomly generated (there can't be two identical)? Assuming an adversary ...
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1answer
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Rotating password with PBKDF2

Crypto is hard. Thank you for helping me learn. My encryption scheme currently looks like this: Salt is stored out in the open Secret is the user's password, known only to them EncKey||AuthKey = ...
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Security when using same salt for different passwords, compared to using different salts?

I have this question I am struggling about: For example, someone suggested improving UNIX authentication by defining 3 different passwords for a user that are stored in the shadow file. All three ...
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1answer
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Do I need to use a CSPRNG when creating salts for user accounts?

I'm not sure about the need of using CSPRNG to create salts for each user account. I found “Cryptographically Secure Pseudo-Random Number Generator in Qt/C++ (Cross platform)” (at StackOverflow) with ...
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Should I add randomness at the end before AES?

Seen AES, changing a character drastically affects the encrypted text. I want to make it harder to decrypt AES I send. So, it seems this can be done by adding some special code and some random bytes <...
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Security implication of deriving key with fixed salt for files authentication

Context: I need to calculate MAC for a collection of files just for future integrity and authentication verification. This is the conceptual order of steps: Derive a 64 bytes key from user input ...
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Increase in security with increase in size of salt [duplicate]

Does increasing or doubling the size of salt result in improved security? It will require some extra time to brute force the passwords, but any added advantage?
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280 views

Reducing the probability that a password will be guessed

In a file users' password hashes are stored. There are 2 approaches to reduce the probability that the password is guessed. Increase the size of the salt from 12 bits to 24 bits. Increase the length ...
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1answer
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Is there an algorithm that allows verification that 2 encrypted or hashed bits of data are the same, given that I may only know half of the key/ salt?

We have an interesting problem. Currently, we store a salted hash of some secret key known only to the clients of our clients to allow us (and our clients) to find other records that were generated ...
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388 views

Hash + Salt v. Hash + Encryption

I was wondering if using a salt with a hash is more effective than hashing and encrypting your hash.
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Could we share a secret key using the Birthday problem?

I stumbled upon this code on-line, it seems obvious to me that generating all 2^40 keys in trivial time can always be achieved as can hashing each and everyone of them, using the SHARED Salt that "Eve"...
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Need for salt with IV

I have mainly referred to this question. Definitely in case of using a salt, IV has a use of adding randomisation to each and every key. But isn't it redundant in case of using an IV to use a salt? (...
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803 views

Making both the IV and salt public for PBE with AES-CFB

Is it okay to make both the IV for AES-CFB and the salt for PBKDF2 public? Does this action of mine compromise security in any way? I have an implementation of this cipher and had previously asked a ...
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1answer
925 views

What effect does a salt have on attacks against hashes's fundamental properties?

I am interested in analyzing how adding a salt to our hashed passwords affects the three types of attacks we can use. The three types of attacks against hashes are as follows: We have the hashed ...
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3answers
815 views

Hash email address with a non-random salt for moderate security?

Crypto noob here. I have an application that has only moderate security requirements (internal use, limited audience). I want to send a unique url with a token in it to each user. If anyone has the ...
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1answer
675 views

Is it true that 7zip doesn't use any salt with its KDF?

This issue claims that 7zip does not use any salt with its key derivation function: https://github.com/magnumripper/JohnTheRipper/issues/1679 If that's true, wouldn't that mean you can crack multiple ...
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2answers
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Algorithm for generating OAuth tokens

I'm trying to find a good algorithm for generating authorization codes, access tokens and refresh tokens in an API. Currently, I am looking into the following setup: Tokens are generated using the <...
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1answer
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Can the salting function complexity improve the hash robustness?

I'm quite novice in security, and all examples I saw seem to salt the password by concatenating it, or by applying a simple binary OR or XOR. So the hash is based on "salt + password", "salt | ...
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1answer
212 views

Is it possible to reverse the birthday attack calculation?

I find that for every 100 password salts in our database, we only average 94.73 distinct salt values (averaged over a total of around 18 million). Is there a way to take that observation and calculate ...
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1answer
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Birthday-attack calculation in planning password salting strategy

The book Cryptography Engineering by Fergusun, Schneier, Kohno section 2.7.1 explains Birthday Attacks: "In general, if an element can take on N different values, then you can expect the first ...
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1answer
474 views

Is it safe to exchange cryptographic salt and initialization vector in messages?

I have a client which does the following: ...
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2answers
410 views

What are the required security properties for salts?

I was recently thinking about password hashing (maybe caused by the PHC progression). I started to think a little more about it and got stuck at this question: What security properties do password-...
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1answer
161 views

Hash and salt or salt and hash?

People say "hash and salt", but aren't you supposed to salt password the first, and then hash it? So that means its called "salt and hash" right?
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1answer
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Salting in asp.net?

I have spent the past hour reading up on salting and still don't understand how it is achieved. Forgive me if im wrong, but the way I am thinking of salting is, storing an ArrayList of random strings ...
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1answer
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Derive cipher IV and cipher Key using PBKDF2 with random salt?

It is said that cipher IV does not have to be secret and the only secret component of the encryption scheme should be a cipher key. Question: is it safe to generate IV using PBKDF2 function, which ...
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2answers
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Is it safe to use a secret salted hash of a public id for client to prove ownership of id to a server that knows salt but does not store ids?

I am writing a peering server - the server assigns randomly generated public IDs to users, and I want users to be able to reclaim their ids in the future, but only to be able to claim ids that they ...
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1answer
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Is it safe to derive two different keys with the same password and key derivation function using two different salts?

I would like to know if the following process would harm the security of a fictional system if the persisted data would be stolen: in this system a user has a single password. The password will be ...
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If I know the salt, can I decrypt the commitment?

Say, I salt my key(K) with y. So, my new Key is K' = Salt(K+y). Now, Alice sends commitment = E[K',M] to Bob. Bob knows the salt(y), but not K nor K'. Can Bob decrypt the message?