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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4
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46 views

What are the recommended scrypt cost factors for 2016?

I've been trying to look for the answer, but the latest one I found was outdated by three years. So what are the recommended scrypt cost factors for 2016?
0
votes
1answer
67 views

Is `/dev/urandom` secure to generate a salt on a Virtual Machine?

I've read the new password_hash() function from PHP uses /dev/urandom to generate a secure salt, however this assumes some noise from device drivers. Is possible that /dev/urandom is not so random ...
0
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1answer
21 views

Hashing and signing partial data in payload

I'm hashing and signing part of a payload prior to HTTP Posting from a mobile device to server side. The payload contains of about 7 data elements and only 3 of them are hashed/signed using a private ...
6
votes
4answers
1k views

Does quick denial tell that you passwords are stored in plain text?

Say you are using a website and incorrectly enter your password. The website then "instantly" pops ups with an "incorrect username/password" message. Would it be safe to infer that the website is ...
3
votes
1answer
89 views

How to detect mimikatz usage on LAN

My boss is has made it clear that we need better ways of detecting mimikatz usage on the network- and I would agree. In place already for detection is suricata/ET PRO rule set on a couple of taps. ...
1
vote
2answers
72 views

Is it possible to find the salt?

I have this PHP code with me : $auth = md5($username.$password.$salt); I have a dummy value : $username = user $password = password And I also have the resulting MD5 Hash : ...
0
votes
3answers
86 views

when to use encoding over hashing?

If encoding is used for integrity someone can tamper it across the network because it is based on some publicly known scheme. When do you use encoding and when do you use hashing for preserving the ...
-8
votes
4answers
133 views

Why shouldn't I store passwords in plaintext? [closed]

Why is it so important not to save passwords in plaintext? I think it is the same issue like authorizing a user on a RESTful webservice, where most developers claim: "Don't send your security token ...
1
vote
1answer
46 views

Powershell and cached credentials

In my environment we have powershell remoting off- I get around this using 2 hop scripts, packages(exe -no creds are stored in code- local privs only), and iwmi. I never pass creds to the endpoint, ...
26
votes
5answers
4k views

How does storing hash passwords work? [duplicate]

In usual network applications, that employ password hashing, is the user password hashed on client side before sending it to the server, or is it sent without hashing as encryption of plain text ...
0
votes
0answers
11 views

Change ntlm hash in memory on the lock screen?

Is there a way to change the ntlm hash in memory to bypass windows login? For example, I have the ntlm hash of a windows machine and I have physical access. Is possible to write the ntlm hash in ...
1
vote
1answer
29 views

Passing a hash of a secret to a server instead of the plain text

Instead of passing an authentication token or api key in an http header to a server in the plain text, what if I calculated its hash and passed the hash? This way even if a adversary intercepts the ...
4
votes
2answers
84 views

Idea for an encrypted pastebin NON-web application

I have an idea for an app that might be useful (though if it isn't, I've still learned in the process, which is what matters). There are a bunch of encrypted pastebin web apps out there (e.g. ...
3
votes
2answers
39 views

Incrementing Work-Factor of Hash Functions Over Time

For a long time hash functions have required a work-factor in order to keep the operation "slow" enough to protect individual passwords in the case of a database leak. Bcrypt and PBKDF2 being notable ...
1
vote
2answers
66 views

Upgrading security of hashed passwords [duplicate]

Let's say we have a database with usernames and passwords, where the passwords are naively secured using a single round of SHA-1 (such as was kinda best practice a number of years ago). Now, let's ...
3
votes
2answers
85 views

What scenario are 'extra' strong passwords and hashing algorithms actually protecting against?

Note: I completely understand the need for strong passwords & I understand that there is an issue of speed with hashing. I am just interested in better understanding the actual negative impact of ...
2
votes
0answers
21 views

The optimal settings of Winrtgen GIU

I'm working with Winrtgen GIU on windows, but I can't fix the right settings to create a rainbow table for a: password length=1-7 Charset=alpha numeric all space What are the ideal values to put in ...
3
votes
4answers
135 views

Is knowing the salt a problem?

I understand that adding a salt would thwart the use of rainbow tables. I don't understand the time it would take to create a rainbow table for a certain salt and of course this is dependent on the ...
3
votes
1answer
62 views

Is appending plaintext to salt equally safe as appending salt to plaintext

Is using hash(salt, plaintext) equally secure as using hash(plaintext, salt), i.e. can the plain text be appended to salt in place of appending salt to the plain text. Why or Why not? What kind of ...
3
votes
1answer
114 views

Two-phase anonymization

EDIT: [N.B: I fully replaced the original question which was not a very good statement of the problem (see comments) with a more apt one.] I have records that contain - among other things - the ...
3
votes
5answers
588 views

Why can passwords be used to encrypt data, but are less strong for authentication?

Encryption software is often password based. Even if the adversary gets your computer they can't get the data without knowing the password, and bruteforcing is infeasible. Websites use passwords to ...
3
votes
2answers
79 views

Is signing android apk file with SHA1 digest secure enough?

Google command line example for signing apk files: $ jarsigner -verbose -sigalg SHA1withRSA -digestalg SHA1 -keystore my-release-key.keystore my_application.apk alias_name source: ...
6
votes
2answers
90 views

Is it good to store passwords in a separate table/database and manage them in a separate process?

I'm quite a newbie at systems architecture and security so I just want to check that this plan makes sense. I'm building a web app and I need to store a password for each user. I've already read ...
-4
votes
1answer
64 views

Sum two SHA256 to get a SHA512 [closed]

I see this code in a web game SHA512(SeedServer + "|" + SeedUser) and I'm trying to reproduce this hash. I tried in PHP: <?php echo hash('SHA512', ...
2
votes
2answers
106 views

Where to store a pepper?

Assuming you're using a pepper in your password hashing, where should it be stored? I know you shouldn't store it in the database since it can easily be found there during a dump and the idea is to ...
80
votes
10answers
9k views

Is there a threshold for a password so long it doesn't get any more secure or even becomes insecure?

I always hear "A long password is good, a longer password is better". But is there such a thing as a "Password is so long it is becoming unsafe" or "Password is long enough, making it longer won't ...
3
votes
1answer
121 views

MD5 Algorithm: A basic explanation of the process

Could anyone please explain the basic idea and steps involved in the MD5 algorithm? I tried reading it on the web (Wikipedia etc.), but it was just too high level for me. So, can someone explain the ...
0
votes
0answers
130 views

HMAC Token - Check Logic

I have a situation where I need a token that provides authentication. The common HMAC procedure I found is: Get Some key using login credentials Create Message, append key and other message data ...
6
votes
2answers
1k views

Can I use SHA-512 hash as AES key?

I want to combine hashing and encryption for better security. So can I use a hash key generated from SHA-512 as a key in AES. For example, I have a password "secret", I calculate SHA-512 hash for it ...
30
votes
2answers
3k views

Is it possible to get hacked if my bcrypt hash is publically known?

I just checked https://haveibeenpwned.com/ and I have noticed that I was pwned, therefore I checked the file that hosts the details of my "credentials", however, I see my email in plain text but the ...
2
votes
1answer
59 views

What fuzzy hashing algorithms exist?

I have been trying to find information on fuzzy hashes, and I have found surprisingly little. I know that fuzzy hashes can be used to detect if a piece of malware has changed slightly. I would rather ...
6
votes
2answers
160 views

How is SHA-1 insecure if it is not vulnerable to what MD5 is?

I have been hearing a lot lately about how SHA-1 is no longer going to be used because of how weak and insecure it is, but if it is not vulnerable to collisions like MD5 is, then how is it weak and ...
7
votes
3answers
72 views

Does verifying an additional fraction of a file decrease the chances of collision?

If I have a file of indeterminate length and I generate the SHA256 of that file, then generate the SHA256 of the first half and the last half, then verify all three, does that decrease the odds of a ...
2
votes
1answer
94 views

Is storing encrypted and hashed versions of the same data less secure?

I have some database columns which are encrypted. Obviously there is no way to filter these by plaintext value. As the data stored in the db is ~~salted~~ combined with the IV, there is no way to ...
0
votes
1answer
53 views

How many hashes do I need to compute to get x collisions?

I know that you need to hash about 2^(N/2) to find a collision taking into account the birthday problem. But I'm not really sure about more than one collision, I mean, collisions with different ...
2
votes
3answers
48 views

Pre-generating 'secure tokens'

In our web app we make good use of single use tokens. For example, when somebody creates any of the three "accounts", resets their password, or any other number of things that require random ...
7
votes
1answer
156 views

Increasing the Calculation Cost of Hashing [duplicate]

Is this a secure way to increase the calculation cost of md5 or sha1? public static byte[] increaseHashComplexityMd5(byte[] hash, int loops) { for(int loop = 1; loop <= loops; loop++) { ...
2
votes
1answer
55 views

php's password_hash with system wide salt [duplicate]

I'm thinking about using password_hash function for generating password hashes. I have read that own salts shouldn't be generated and instead use the default one that the function generates. Own salts ...
1
vote
2answers
63 views

How can i Identify and use hash function given enough text and their hash?

So, I have this old program currently in use, as i have access to the database i have adopted all data i need except the user passwords.. Now users will provide me with the plain text password and ...
3
votes
1answer
51 views

Can I generate a random 32 bit key by using the Java hashCode and random English words?

I want to generate and communicate a 32 bit key to Bob over a phone conversation. I know he happens to have the same Java and OS installed as I have. Suppose I have a dictionary of 100,000 (English) ...
0
votes
1answer
67 views

Checking a salted hash against known password?

I've created a mysql dump of my users and passwords and awked them into a presentable form: Passwords: ...
1
vote
3answers
69 views

Are hashing functions designed to be injective where the domain is limited to the codomain?

Using the example of md5, I would like to know if md5(h₀) == md5(h₁) for some distinct md5 hashes h₀, h₁. Are hashing algorithms generally designed to avoid this sort of collision? Do MD5, SHA1, ...
32
votes
7answers
5k views

How to prevent username and password matches when changing a username?

Let's say that I have a system where one of the security requirements is preventing users from choosing a password that matches their username. Usernames are not case sensitive but the passwords are. ...
5
votes
2answers
145 views

Why is weakness of SHA-1 considered a threat to TLS security

If I understand correctly the role that a hashing algorithm (e.g. SHA-1) plays in TLS certificates is as follows: The hashing function is applied to a subject's public key. The CA then uses their ...
0
votes
1answer
73 views

Is there a way to securely check if a password is one of the most used ones?

So lets's say that a user wants to register to some website. For whatever reason, I want to not allow that password if it is one of the top 100 passwords used on my site (So I'm not checking against ...
3
votes
1answer
190 views

Is this encrypted information? Why is it in a URL?

There's a vendor who sends us reports full of links to articles. Some of these links, especially ones that perform what I'm guessing is an HTTP verb of some kind, look like this: ...
1
vote
6answers
4k views

Is this authentication scheme secure?

I want to authenticate a client of a webpage and make sure it is a particular user. Let say that we already agreed on a particular hash (SHA256, actually, which I think is secure enough for this) and ...
0
votes
2answers
96 views

Password based Asymmetric Key generation

I am looking for a password based key derivation scheme that results in an asymmetric key pair. I have worked with PBKDF and its variants but could not come up with any way of generating a key pair. I ...
2
votes
1answer
108 views

How might a PIN based Web authentication scheme work?

I'm interested in implementing PIN based authentication for a web application, similar to what Facebook provides in their mobile web site. Here is the user flow: User visits the site for the first ...
-2
votes
2answers
56 views

Is there a reason to salt instead of enxrypting data? [duplicate]

Is it more secure to: a) Take a password, salt it, then hash it. b) Take a password, hash it, then encrypt it(Using a symmetric algorithm with a large key)