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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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714 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
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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
757 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
380 views

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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106 views

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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444 views

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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1answer
270 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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372 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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725 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
814 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
704 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
610 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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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
122 views

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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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
295 views

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
440 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
379 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
155 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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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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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
262 views

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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282 views

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?
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Viability of an “Unconventional” Hashing Scheme?

I am playing around with the following hashing scheme: Start with a domain string (same for all users), Allow every user to mutate it in any way defining their own custom replacement rules, Append ...
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Recovering a constant salt for MD5 [duplicate]

I have STRING and MD5(STRING+SALT) for any infinitely many STRING's. Is their any way that I can recover the SALT itself? (SALT is constant) I actually know SALT, but this is an intellectual exercise. ...
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Is there (this) a case in which salting is dispensable?

tl;dr this is not a duplicate of "what is a salt/why use salt?" question. Instead it is specificly asking when salt may not be necessary for hashing securly? (i.e. when the data being hashed is ...
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Definition of “pepper” in hash functions

I am confused about the notion of "pepper" in the context of storing hashes of users' passwords. Definition 1: A pepper is a secret key Looking around the Internet, for example here or here, a ...
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1answer
455 views

Storing salts and iteration number?

I have a function that derives two sub-keys from one passphrase using PBKDF2 one which is used as a encryption key the other for HMAC generation, because these two sub-keys will need to be regenerated ...
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2answers
225 views

Is it safe to salt a MAC?

Say that I define a scheme where the salt is public and is MAC-ed with the message: $k = KDF(password, salt)$ $tag = MAC_k(salt || message)$ Is it safe to salt the MAC this way? Assume that the salt ...
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1answer
99 views

How are salt values more secure?

If a database stores password encrypted by using salt values, how are they stored? I read somewhere, it uses timestamps. So is the timestamp also stored? How about when a user tries to login next ...
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1answer
650 views

Session based AES with random key and static salt

I'm currently using aes to encrypt/decrypt messages to and from a web service. When the user establishes a session he sends a random generated secret via rsa public key. This secret is used to ...
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INT_32_BE in PBKDF2

Trying to understand PBKDF2 in detail. It is clear that the password and the salt is given to the PRF (which is HMAC-SHA-1 in the specification). But what is the role of the INT_32_BE(i)? What does it ...
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Are password salts equivalent to keystream?

I was reading up on keystream when I came upon the definition of it: A keystream is a stream of random or pseudorandom characters that are combined with a plaintext message to produce an encrypted ...
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Should you change salt when changing password?

Assume a password storage scheme using a computationally-expensive hash algorithm and a CSPRNG salt. User ID, salt, and hash value are stored in a table; if the table is compromised, all three ...
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Using hashes as passwords

I have thought of a system for generating passwords which works as follows: Take the following items: A password, such as williamwallace. A secret 1000 digit ...
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1answer
558 views

Key Derivation from random salted seed, HMAC and HMAC based KDF

I would like to generate a key which would be good enough to be used for encryption with AES in a mobile environment. My idea is to use as a seed ''random attributes'' from a mobile device. Is hashing ...
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1answer
1k views

Importance of salt when deriving an encryption key

I'm very curious to know this and a bit confuses too: Suppose, I have two files encrypted using AES-128bit with keys PBKDF2-derived from the same password and the same salt. If an attacker does brute ...
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Does adding a salt to the message before HMAC processing add any security?

An HMAC function is designed to verify message integrity, i.e., that the message has not been tampered with. It is generally (always?) implemented by using a hashing function ...
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Could scrypt salts contribute to entropy if passwords & salts are only stored in human memory?

I'm unsure of how exactly the salt is manipulated by scrypt and its potential contribution if any to overall password entropy if passwords & salts are stored only in human memory for a ...
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Does salt size affect password hash security?

I use PBKDF2-SHA512 with an iteration count of 128,000 to hash my passwords. I use a CSPRNG to generate a salt per password. However, I am unsure about the ideal size of the salt. I have read a lot of ...