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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1answer
384 views

What type of hash is that [closed]

Hey do you guys know the algorithm used to generate this hash? 6874747a3b202063733437373676342f766c2f6e6520753933313538343931206175646960732039‌​353861383a3a36663836392f6e7a3325313638 It's ...
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1answer
240 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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3answers
268 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 ...
0
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1answer
141 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
77 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 ...
18
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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 ...
2
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1answer
169 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 ...
2
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4answers
724 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 ...
21
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2answers
7k views

What is the difference between a Hash Function and a Cryptographic Hash Function?

I mean, is it just a matter of "how difficult is it to reverse the function with the current technology"? Or is there a mathematical concept or property that makes them different? If it is a matter ...
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2answers
65 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
169 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
367 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
78 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 ...
0
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4answers
303 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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3answers
83 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 ...
3
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1answer
144 views

A pair of 'self-signing' hashing functions? [closed]

Does a pair of (hashing) functions for which where neither g(x) nor f(x) are constants exists?
4
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5answers
673 views

When hashing passwords, is it okay to store the algorithm used right there in the database?

Since hashing password has become a hot topic recently, it is only natural to expect things to change and assume that some time down the road you might want to replace/tweak the algorithm used in your ...
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5answers
11k views

How does hashing work?

I have been interested in Information Security. I was recently introduced to the idea of hashing. What I currently understand about hashing is that it takes the password a user enters. Then it ...
2
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2answers
79 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
157 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 ...
0
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3answers
156 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 ...
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2answers
115 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, ...
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3answers
943 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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2answers
1k views

LastPass Grid Authentication vs Google Authenticator which one is more secure?

[Being a LastPass user] recently I moved to Google Authenticator instead of using Grid Authentication as a 2-factor security. For me, finding and filling letters from such a dense matrix is a rather ...
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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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3answers
354 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. ...
3
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2answers
120 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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2answers
2k views

openssl_digest vs hash vs hash_hmac? Difference between SALT & HMAC?

openssl_digest vs hash vs hash_hmac I want to use SHA512 for storing password. Which of the above methods are best to use? Why? What is the difference between SALT & HMAC? I just read ...
6
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4answers
7k views

Bank account number and account holder in check exposed?

I'm not sure if this is standard practice in all banking institutions but almost all banks where I've received checks the account number of the issuer is exposed (some even the account name). Isn't ...
142
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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
591 views

Hash user id securely

In my app I'm using Facebook login and creating a local user in my DB after retrieving the data. When saving the Facebook ID in the DB I need to hash it, as I don't want the ID to be in clear text if ...
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1answer
81 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
82 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 ...
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2answers
184 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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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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1answer
133 views

Ldap differences between {crypt} and {CRYPT}

I recently stumbled upon some password entries in LDAP marked with the {crypt} scheme. Since all recent entries are {CRYPT}, I was wondering what the differences between the hash algorithms are.
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4answers
500 views

Hashing a key: less entropy than the key itself

A web API needs to store a 'key' for authentication, in much the same fashion as a password but at 128 characters. My concern is that the salted SHA1 hash for the key has less entropy than the key ...
0
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2answers
221 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
191 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 ...
2
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2answers
607 views

How secure is the PwdHash algorithm and system?

I use the PwdHash service (http://crypto.stanford.edu/PwdHash/) and plugins for pretty much all of my passwords. I believe this is safer because: No service gets the same password as another, so if ...
2
votes
3answers
675 views

Time Memory Trade-Off Attacks

Given, we want to crack a password. With Time Memory Trade-Off Attacks one tries to find the right balance between time to compute hashes for all possible passwords. And the used memory to store all ...
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2answers
96 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 ...
0
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1answer
126 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, ...
1
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0answers
29 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
85 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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2answers
1k 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
83 views

Security of this account login system

I have an idea to implement a account system using email and passwords for games. Im intending to have the account creation and forget password systems on a webpage. So if users will have to access ...
0
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2answers
346 views

Is there any issue using the PHP crypt() function with an additional salt?

Is my PHP authentication script secure? I noticed that the hashes start with the first two letters of the username. Could there be a security flaw using crypt() in such a way? <?php // ...
8
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1answer
376 views

General purpose slow/unique hash routine for dup checking of private data, without storing the data itself?

I am wondering if there is a percentage of uniqueness known to be lost with every repeat of various hash routines, like MD5, SHA1, and how that might compare with other algorithms. If theoretically I ...