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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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 ...
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2answers
213 views

Is this hash function safe?

Below is the hash function implementation of the roguewave library. It returns a 32 bit hash. The core operation is A = B ^ ((C << 5) | (C >> 27)). Is this hash safe to use as a password check ...
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1answer
85 views

How to check for presence of LM hashes in local SAM

To get rid of LM hashes in local SAM databases, one can rely on the famous NoLMHash domain GPO, which instructs clients not to store password hashes with the LM algorithm locally ("Do not store LAN ...
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1answer
61 views

What multiplier to use when calculating the average time to crack passwords with a given entropy?

Suppose that we have a process that generates passwords with entropy E. I'd like to compute the average time it would take for a brute-force attack to crack an MD5-hashed instance of such a password. ...
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1answer
69 views

Can HMAC leak the password? [duplicate]

Imaging the following pseudo-code: h = hash(sha512) h.input(password) h.input(message) send h, message to client If the user has the hash and the message, and the only missing variable is the ...
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1answer
153 views

Is encrypting something more than once safer than hashing more than once?

I am aware of the implications that hashing something more than once correctly will increase the security of a system, but doing it incorrectly will decrease it, as noted here and on various other ...
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3answers
244 views

Does figuring out what one password hashes to allow you to crack all identical passwords?

Forgive me, as I am very new to cryptography, but it seems interesting, and I have a question. I'll state my beliefs and please feel free to correct me on the aspects that I'm mistaken so i can ...
2
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4answers
702 views

Using last characters of hash as salt [duplicate]

In a recent discussion somebody mentioned the following hashing scheme: passHash = sha256(password) saltedHash = sha256(passHash+passHash.substr(-10) finalHash = sha256(secret+saltedHash) The ...
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4answers
2k views

Should I use own constants when using well known hashing algorithms?

I understand that it is important to use well known and well tested hashing algorithms instead of designing my own. For such there often are reference implementations available, which initialize the ...
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2answers
52 views

Identifying/decrypting hashed/encrypted data [closed]

This weekend I took part in an security challenge. I had great fun doing it but i found a huge gap in my knowledge that I'm really keen to fill and hope someone here can help get me pointing in the ...
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2answers
99 views

Difference between OS X md5 and gnu md5sum

I have installed the "md5sum" utility on my Mac and there was also a "md5" binary pre-installed in /sbin. My problem and question is this: "Isn't MD5 a standard algorithm?" Because I get different ...
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2answers
350 views

Are newly-generated recovery passwords sent to me via email hashed? [duplicate]

If a company sends me a new password via SMS/email because I clicked "forgot my password." Does that mean the company is not actually hashing my passwords?
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4answers
69 views

Confidentiality of file hashes

Context: I have a directory full of sensitive company files. I want to compare these files with a colleague at a remote location, without the need for a secure connection. Is it safe for me to ...
3
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2answers
325 views

Why is a CSR hashed?

What are the use cases for defining something other than the default SHA1 hash in a CSR? Is it to protect the digital signature, public/private keys? What is it protecting exactly?
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0answers
44 views

Do I need a salt when hashing a CSPRNG?

I have passwords stored in my database that are very long CSPRNG and unique. Do I need to use a salt before hashing them? My understanding is that usually you use a hash function in the following ...
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3answers
79 views

What does one call the strategy of using “pre-password transforms” as passwords?

Suppose that instead of using, say, Google, let me in! as my Google password, I used some consistent transform of this string, say ZWE1NjMyNm? What search keywords would be helpful to search for ...
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4answers
190 views

How does a hashing function always return the same length hash?

I've been looking into what hashing functions are, what they do, &c. I was just wondering: how does a hashing function always return the same length hash? How does hashing work? does not explain ...
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2answers
73 views

Should security phrases be hashed?

I didn't think of this before but today I just realised that in soke sites, pw recovery is possible if you know the answers to security questions like What is your mother's maiden name? In this ...
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3answers
121 views

“Remember me” cookies - did I implement them securely?

I am currently working on a pet project website and I want to implement the "remember me" feature for logins and wanted to know if my procedure is secure. The authentication process basically goes ...
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3answers
135 views

Did the “Malicious SHA-1” technique enable the NSA to insert a backdoor into SHA-1?

SHA-1 was standardized by the NSA. It appears to be possible to choose the constants in such a way that collisions can be derived easily. Yet, it is not easily possible to discover that the constants ...
16
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2answers
1k views

Methods for slowing down a hashing algorithm

I understand why a hashing algorithm should be slow but is the method that makes it slow important to the strength of the hash? Everything I've read says that the algorithm should be computationally ...
0
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2answers
90 views

Simplest way of hashing a password with multiple different hash algorithms [closed]

I have a list of plaintext passwords that I would like to hash with various different hash algorithms (for educational purposes). As a minimum I would like to obtain hashes under MD5, SHA1, SHA256, ...
7
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3answers
798 views

Not hashing email registration confirmation link

I sent emails out that contains an email registration confirmation link: http://example.com?create=email%3Djay%40gmail.com%26confirm_key%3D53e321f97c145 I do not hash the link above. Before I sent ...
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1answer
155 views

Native app, token authentication without login/password

I'm working on a always online mobile game (native android/iOS app with Unity) and i would like to be able to authenticate the player without requiring any login/password at the beginning. For those ...
7
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2answers
1k views

Is it bad practice to ask only for individual characters of a password? [duplicate]

Some financial websites that I use use passwords in a peculiar way. Instead of asking me the whole password string, they only ask me to enter e.g. "3rd, 5th and 8th character of your password", i.e. a ...
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2answers
90 views

Related-password hash security

Say we are given a strong cryptographic hash function hash(), a strong completely random password of 15 characters pass15, two single-character salt values salta, saltb. We compute the hashes hasha, ...
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3answers
238 views

SHA and “Bits of Security”

I've researched several forms of encryption/hashing and have often come across the term "bits of security". For example, at least one source claimed SHA-256 = AES128 = ECC256 = 128 bits of security. ...
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1answer
58 views

Can I test/determine all decryption types on an unkown filetype. I do have the password [closed]

I have a file that's nearly 200Mb. It was reportedly packed/encrypted with Kruptos 2. But it has a .~enc extension. The header of the file is pure gibberish. Running file says it's data running ...
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3answers
77 views

Can I safely use my own statistics to assess password strength on number of times a password is used?

Lets assume I want to give my hypothetic 10mio users userbase a good feedback on their password strength. Besides the classical entropy tests and top500 list of bad passwords, I might want it to be ...
7
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4answers
1k views

Should the password of a password protected channel be hashed?

Let's take a chat system, where any user can create a channel with a password protection. Thus, other users may only join using the channel password. This password is therefore known to every person ...
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2answers
103 views

How can I identify this hash? [closed]

I'm trying to decrypt my router's root password, since I only have access to a simple admin account that doesn't have root privileges. Here is the passwd file: 0:F.bCrWv/Oxp6.:0:0:root:/home:/bin/sh ...
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2answers
119 views

Saving passwords decryptable for later usage

I'm in a situation where I need to calculate a hash of the result of the password in plain text plus some random chars representing a session. The gained hash will be compared to another hash that is ...
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1answer
156 views

Tracking IP address to prevent abuse without logging user metadata

I am trying to balance good security practices against excessive logging of user metadata / Personally Identifiable Information. I am constructing a web app that tracks IP addresses to prevent abuse, ...
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2answers
128 views

What is the collision likelihood of MD5 when non-numeric values are removed?

Start with a unique identifier String macAddress = "CC:3A:61:24:D6:96"; Hash the identifier via MD5 implementation String hash = md5(macAddress); //bd37f780e10244cf28810b969559ad5b Remove all ...
138
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18answers
14k views

What is a good analogy to explain to a layman why passwords should be hashed?

Note: This is not an actual situation I'm currently in. Assume your boss is one of those old-fashioned computer-illiterate managers and wants to store the passwords in plaintext to simplify ...
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2answers
64 views

How Empathy - a messaging program, is storing my passwords

I am connected to my chat accounts via Empathy, a messaging program, and it has my password stored in it. I am really curious to know how it is storing the passwords, and if there is any they can ...
27
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7answers
4k views

Hashing a credit card number for use as a fingerprint

What's the best way to hash a credit card number so that it can be used for fingerprinting (i.e. so that comparing two hashes will let you know if the card numbers match or not)? Edit Looking for ...
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0answers
22 views

PBKDF2 hashing over TLS for encrptig password [closed]

i wanna use PBKDF2 hashing over TLS for encrypting password and session and that way stop hackers from breaking into my connection. How to do it in java.
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2answers
82 views

Is there any way to log in with a hash?

I've understood that the following steps are taken when I log in to a site: 1. My password is hashed 2. The hash is compared to what's stored in the database. 3. If the hashes are equal, I can log in. ...
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1answer
114 views

Save password on user-side for autologin

If a user wants to login to a system/server, it's recommended to have the hashed&salted password saved in a database, along with its salt. So the user wants to login, types in the password, ...
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2answers
543 views

Reversible Hash Function?

Is there any reversible hash function? The hash function like SHA and MD5 are not reversible. I would like to know if there exist some reversible hash functions?
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2answers
122 views

How to generate an unpredictable but short string? [closed]

I want to built some short urls for uploaded files and links on my own server. Simple enough, I upload files and my script returns me a link. On access, the link is translated to the file and download ...
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4answers
299 views

What if I develop my own hash algorithm to create strong passwords from easy ones?

I came up with this idea but I cant figure out if it's good or bad, maybe you can help. My goal is: I want to create extremely strong passwords for my main accounts (gmail, skype and so on). I want to ...
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2answers
93 views

Is it unsafe to hash one password with more than one salt?

I'm asking my question here since I was not able to find an answer anywhere. I have written a piece of software which stores pretty delicate passwords. I have used BCrypt as hashing algorithm with an ...
1
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1answer
124 views

Advice on using encryption and hashing

I'm going to rephrase a question I asked earlier, as I don't think anyone understood what I meant. Bascially I'm writting a web based password locker, which can have multiple accounts; so that users ...
1
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1answer
70 views

Using encryption and hashing

I'm writing a project to securely store and share passwords between users, I've been doing tons of research into encryption algorithms, CSPRNGs, hashing algorithms, key stretching etc... I just want ...
3
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3answers
210 views

Client-side hashing of password before sending it from login form [duplicate]

I have just realized, that my web application is sending unencrypted passwords from login form. It's just like that -- I've analysed, that string sent by user from login form is hashed with MD5 (which ...
3
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3answers
668 views

Is this a secure way of storing passwords? [duplicate]

So a couple years ago when I was learning basic back-end web development, I found a tutorial for creating a basic log in system. I haven't done much modification to the code since, but I have the ...
3
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4answers
625 views

How to properly anonymize data, if hashing isn't enough?

Today there are news on Bruce Schneier's blog and ArsTechnica about how NY City released information about Cab/Taxi drivers, their trips, and so on. Basically, sensitive information was simply MD5 ...
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1answer
93 views

Using hashed password as secret key for hmac to avoid exchange of secret between server and client

I'm currently trying to improve our API to be more restful, therfore avoid any state on the server. I want to accomplish this with a hmac token, appended on every request. The hmac will be made with ...