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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Do bad passwords produce bad salted hashes?

When you have a password stored in a database that has been strongly hashed and salted does it really matter if the underlying user password is weak? If you setup features like limiting login ...
1
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2answers
59 views

XOR-Cascade of weak hash secure?

I have following theoretical question: Let H(X) be a hash function which is considered as weak because collissions can be produced (e.g. SHA1, MD5). I wonder if following functions: H2(X) = H(H(X)) ...
3
votes
1answer
85 views

How to best to secure data over HTTPS

My aim is to have an (iOS) app in which the user would login, then on sucsessful login, gain access to additional information over an encrypted webservice (undecided). From research, I understanding ...
8
votes
5answers
2k views

Should I remotely store my salt? [duplicate]

When users register on my site, I want to store their username and hashed password in my database. When I hash that password, I'm going to salt it using PHP. The issue is, I don't want to store the ...
0
votes
3answers
59 views

How SplashData knows about Worst Passwords used by users annually

It is known that every reputable website stores their user passwords into their database after implementing some hashing algorithm on it, and even they don't know what the actual password of the user ...
0
votes
1answer
110 views

Identify an unknown type of hash [closed]

I've come across an unknown type of hash value which looks like this: AAAAAATOM2KIII+kbR/Dqw3TLTw4PHsGPZft2c+b93rImFIuAQ== The corresponding hex string is: ...
1
vote
1answer
45 views

truncated hash for message authentication?

I am using hash for authenticating the signature of the message. since the hash will be part of a url that is used for QR code, I would like to keep the hash as short as possible in order to generate ...
-2
votes
1answer
96 views

What is “Pass the hash” attack?

The article on Wikipedia doesn't explain how the attacker can authenticate to the remote server using the hash instead of the original password. According to the following article the attack is still ...
3
votes
2answers
239 views

Is it unsafe to have hashes of parts of a private string

We have string B and the hashes hash(P+B), hash(P); is it possible for P to be revealed easier using this information than having hash(P) ? What is the difference ? Any links to articles or any ...
1
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2answers
133 views

Is it a good idea to use the user's username as a salt when hashing a password like hash(username_str + password_str)?

I'm helping my friend with hashing his passwords, and I've a question - Should he use one secret string as salt for hashing or is it better to have each user its own salt for hashing? Consider these ...
-2
votes
3answers
141 views

My friend hashes passwords with SHA512 algorithm without salt. How do I convince him that he needs to add salt?

Today I discovered something incredibly stupid - my friend hashes user passwords with sha512 algorithm without a salt. I immediately raised this issue to him but he said he wants to see anyone crack a ...
2
votes
2answers
98 views

Difference between Second Pre-image Resistance and Collision Resistance in Cryptographic Hash Functions

I am studying the subject from these notes. However it is not clear what is the difference between "Second Pre-image Resistance" and "Collision Resistance" properties of Cryptographic Hash Functions. ...
2
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1answer
66 views

Security of shared “super pin” code table at meineschufa.de

The german brank credit report service "Schufa" uses a so called "SuperPIN" to enable users to reset their password. This super pin is a permutation of 30 lower and upper case letters and digits and ...
1
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0answers
99 views

Breaking it gently

Let's say I've found a fundamental error with mathematics of a security package. For example, let's say I've found something similar to the Pollard’s \rho-1 algorithm that renders some of the RSA keys ...
3
votes
1answer
139 views

Windows system password hashed - see which hash is used

How can I know / see if my windows is using NTML, LM, NTML2 for its user account passwords? What is the standard today, in windows systems?
1
vote
1answer
68 views

Can a known MD5 hash limit the search space for SHA1 collisions?

For a course in game theory, we are dealing with BitTorrent and alternative strategies (roughly alternative clients) we can employ to maximize our download speed. One strategy is to over-report the ...
1
vote
0answers
377 views

John the Ripper - Calculating brute force time to crack password

I'm using incremental mode (brute force) mode in John the Ripper to crack Linux MD5 passwords. I'm trying to calculate the time it will take to run through all combinations of 12 passwords (with 12 ...
3
votes
3answers
499 views

Accepting other similar passwords when storing a salted, hashed password

If a website stores passwords as a salted hash, is it reasonable to accept similar passwords as correct? For example, given the password stackexchange, does it dramatically decrease security if the ...
6
votes
3answers
249 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?
7
votes
2answers
443 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 ...
1
vote
1answer
101 views

Adding hash value to user supplied URL in a web application: any security benefit?

We administer a Java web application from an external supplier where we have access to the source code. The user is able to provide an external URL which is stored in a database and later on embedded ...
4
votes
1answer
169 views

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. ...
0
votes
1answer
102 views

How to decode/decrypt strings of text [closed]

So I'm trying to decrypt/decode some text strings. I don't believe they're hashes because they vary in length too much and the software they are used for is able to easily decode them and display them ...
0
votes
3answers
113 views

Is is necessary to encrypt the message digest?

In symmetric key settings, in order to provide the message integrity, we compute the hash of the message. The message along with the message digest is then encrypted. Is it necessary to encrypt the ...
10
votes
2answers
237 views

How safe are signed git tags? Only as safe as SHA-1 or somehow safer?

How safe are signed git tags? Especially because git uses SHA-1. There is contradictory information around. So if one verifies a git tag (git tag -v tagname), then checksouts the tag, and checks that ...
-1
votes
1answer
694 views

How do I hash a password in C#? [duplicate]

I assume that the best way to handle passwords for a website is I create a hash of the password and save that hash in my database. Then when someone tries to login, I do a hash of the password they ...
1
vote
2answers
135 views

Search on hashed data

We have a request to encrypt customer personal data (e-mail, address etc.) We use MySQL which does not have any TDE like MS SQL or Oracle. So along with encrypting data we need to preserve ...
2
votes
3answers
133 views

Is it ever safe to publish hashed data?

I'm having a friendly debate with someone who thinks that a website can safely make public sensitive data about it's users as long as that data is hashed (don't ask why, it's a long and hypothetical ...
0
votes
2answers
44 views

Protect against malicious client with key derivation function (PBKDF2)?

Consider a protocol that allows clients to retrieve XML "forms" from a server. Forms are identified by a unique, randomly generated form ID that is embedded in the form. Clients fill out the form and ...
0
votes
3answers
2k views

What are the differences between dictionary attack and brute force attack?

Can someone explain the major differences between a Brute force attack and a Dictionary attack. Does the term rainbow table has any relation with these?
0
votes
1answer
78 views

Secure log in without sending plain test to server

I know this question asked so many times, but here I am again with it. I am working on an application in which I need to log-in users but the question is it is not a good Idea to send user credentials ...
3
votes
2answers
182 views

Is there a strong reason to salt and hash passwords when password reuse is not an issue?

I am dealing with a system (in development) that uses randomly generated (not user provided), unique, strings to authenticate services that will consuming an API. Right now, these strings are stored ...
7
votes
4answers
1k views

Why secure encrypted data consistency by strong hashing?

Consider the SSH protocol: the SSH packet is like [data, SHA1(data)]. The packet is entirely encrypted by a block cipher. The question is, why do we need a strong hash to protect the packet ...
3
votes
2answers
169 views

How safe is to secure sensitive content by URL with MD5 hash and no other authorization?

Suppose we have website that use MD5 hash in URL like this: http://somewebsite.com/XXX/ where XXX is MD5 hash. Content of this website may have sensitive information like transaction details with ...
13
votes
3answers
1k views

Trying to understand why signatures in root certs “are not used”?

Taken from here: Don't worry if the root certificate uses SHA1; signatures on roots are not used (and Chrome won't warn about them. Why are the signatures not used? Are not root certificates ...
0
votes
2answers
66 views

Is my Password Hashing Secure or not?

I have recently created a code for hashing password. Can you please give your advice over the security of my code? The function takes a password, then converts it to a number. #include <string> ...
4
votes
1answer
130 views

Using random number to salt passwords

in a project I have, I'm salting passwords with 3 salts at the moment... Static salt - hard-coded into the source-code. Randomly generated salt (using a function designed for generating password ...
0
votes
1answer
104 views

Idea for an algorithm to authenticate users with zero-knowledge-proof [need thoughts/review]

I have an idea for an algorithm. I don't know if I made any mistakes and need some extra thoughts/peer review on it. This would work as an (almost)zero knowledge proof for sending passwords that can ...
0
votes
2answers
70 views

Authenticate User Salted Hash Without Username

I've got a page with a login system where you type your username and password, the salted hash gets pulled down from the database depending on the username ... SELECT hash FROM db WHERE username = ? ...
1
vote
2answers
130 views

Why is the brute force search time for hashing algorithms 2^(num_bits / 2)?

I noticed that the brute force times (the time it takes to find a message that hashes to a given hash) of various hashing algorithms seems to be 2^(num_bits / 2). For example, people say that brute ...
2
votes
1answer
161 views

HMAC secret key for securing communication - how to keep private on DB

I have a mobile app that communicates to server over HTTPS. To authenticate the client and to make sure its who I believe it is, I return upon successful signup (apart from the username) a secret API ...
-2
votes
1answer
148 views

What hash version is implemented on ThePirateBay.se? SHA-1 or MDA-5? [closed]

I downloaded a File Checksum Utility executable file from Microsoft. This tool is for checking the hash of a file. I'm wondering what is the version of the "Info Hash" section on the torrent site ...
-2
votes
1answer
87 views

client side and server side hash password [duplicate]

Another question about client or server side password hashing, I know. After reading many other post about this topic I'm still a little confused and not completely sure what is the best, because I ...
6
votes
1answer
490 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'?
0
votes
1answer
67 views

Good way to make a secure token for logged out users

I work for a firm that has a marketplace on the web. We want to make a link with a token that stops an ad on the marketplace without the user being logged in. Someone suggested that we make a token ...
2
votes
4answers
546 views

Is hashing the hash considered an extra level of security [duplicate]

As in md5(md5(md5(x)))... I can remember coming across that in some piece of code. If the attacker can somehow reverse md5(md5(md5(x))) into md5(md5(x)) then he certainly can reverse md5(md5(x)) into ...
0
votes
2answers
119 views

Do hashes repeat themselves?

I am not sure how hashing works exactly, all I know it is impossible to reverse it. All hash types have X amount of characters in them while the phrases and made up words can have an infinite quantity ...
0
votes
1answer
90 views

encrypted lookup-keys for key-value store

I'd like to use a key-value store (cassandra, redis, ...), but I don't trust the server. The clients have a shared secret, and I'm using that to encrypt the stored values. But what is the proper way ...
-2
votes
1answer
258 views

What type of hash is that [closed]

Hey do you guys know the algorithm used to generate this hash? 6874747a3b202063733437373676342f766c2f6e6520753933313538343931206175646960732039‌​353861383a3a36663836392f6e7a3325313638 It's ...
1
vote
4answers
277 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 ...