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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Are salted SHA-256/512 hashes still safe if the hashes and their salts are exposed?
Scenario: a database of hashed and and salted passwords, including salts for each password, is stolen by a malicious user. Passwords are 6-10 chars long and chosen by non-technical users.
Can this ...
22
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7answers
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Is salting a hash really as secure as common knowledge implies?
(I did search on this topic, but I found no complete question/answer that addressed it, or even good portions of questions that might be relevant.)
I'm implementing a salt function for user passwords ...
10
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7answers
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What are the realistic, and most secure crypto for Symmetric, Asymmetric, Hash, Message Authentication Code ciphers?
I'm interested in updating this two pronged question for 2011:
What cryptology is most appropriate for low-powered devices (such as a cellphone), and yet still effective?
What cryptology is most ...
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3answers
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How would you store a 4 digit pin code securely in the database?
I'm familiar with password hashing, using salts, bcrypt etc.
But it doesn't seem like this would work to store a 4 digit pin code since the attacker could try all 10,000 combinations quite quickly. ...
12
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7answers
998 views
Tripwire - Is it security Theater?
Tripwire type intrusion detection systems supposedly protect your system from rootkits, by monitoring the checksums of important binaries for changes.
Let's say I have tripwire configured to run ...
12
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2answers
3k views
Which SSL/TLS ciphers can be considered secure?
The OpenSSL website provides a long list of different ciphers available for SSL and TLS.
My question is, which of those ciphers can be considered secure nowadays. I am especially interested in HTTPS, ...
17
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4answers
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When hashing passwords, is it ok to use the hashed password as the salt?
I don't like this idea. But I can not come up with a technical argument against it. Can somebody explain it to me? The basic idea is:
$passwd = 'foo';
$salt = hash($passwd);
$finalHash = hash($passwd ...
9
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4answers
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Does symmetric encryption provide data integrity?
Let's say I have one server that encrypts a file with a symmetric key, e.g. AES-CBC, and sends it to clients that decrypt it. Does that provide data integrity when decrypted? Or is it possible for ...
8
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2answers
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How big salt should be?
I will be using scrypt to store passwords in my application. As such, I'll be using SHA-256 and Salsa20 crypto primitives (with PBKDF2).
Having that in mind, how big salt should I use?
Should it be ...
6
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5answers
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What is the problem with chain hashing?
Let's say that my password is a single character: "a".
Couldn't I chain hash it 1000 (or more) times and make it nearly invulnerable to rainbow table attacks and brute force?
Why isn't this ...
0
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2answers
186 views
Knowing Hash Algorithm from Hashed String
I found an application which stored its password in database as:
A69F00623BE6B8
It's a 14-character string length. How do I know this password algorithm? What's the keyword to describe this ...
37
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5answers
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Password security in databases - today still best practice? [duplicate]
Possible Duplicate:
Which password hashing method should I use?
There are a ton of great posts about password security in databases on stack overflow and on other sites and as I am ...
20
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1answer
1k views
Has SHA-3 Arrived?
I know NIST called for contenders (in 2007) regarding the new hash algorithm to replace SHA-2. Has there been a selection, or finalists selected?
15
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2answers
828 views
Salting password with the first 8 bit of the password itself
Do you guys think salting password with the first 8 bit of the password itself will have same result as using stored salt to hash password?
[Clarification]
I am not storing salt but creating from the ...
10
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4answers
892 views
How secure is the SRP that Blizzard uses to protect passwords?
Blizzard very recently announced that their network was compromised, but they assure users in their statement that the password information that the attackers had access to was saved in a secure way:
...
9
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3answers
775 views
What is a good enough salt for a SaltedHash?
Since I'm hashing all passwords with each their own salt, is there a benefit to the salt being really random, or would an incremental counter or a guid be good enough? Also, is there a benefit of ...
8
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4answers
310 views
How to evaluate the strength of a hashing algorithm?
At work the hashing algorithm we use for passwords appears to be bespoke. Obviously that's a pretty bad idea, but the management don't seem bothered.
The algorithm always produces 20 character long ...
8
votes
3answers
753 views
Using MD5 for malware ids: collision attack risks?
It has been known since 2004 that the MD5 hash is vulnerable to collision attacks (update - not "preimage" attacks - my mistake....). Yet it still seems that people are using it to identify malware. ...
8
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1answer
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Is there repetition in the Solaris 11 hash routine? Can I add some?
Solaris 11 now uses SHA-256, so we can have longer than 8 character passwords now, by default. That is nice.
I'll just make it clear that this password is never used as a line of defence. Only a ...
6
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3answers
229 views
Increase the security of an already stored password hash
Right now we're using 1024 byte PBKDF2 with 256 byte user-specific salt and variable iterations. However, I would much prefer to be able to, perhaps once every year or two, to be able to flat out ...
6
votes
2answers
609 views
Stretching a hash, many iterations versus longer input string
I have been reading up on various password hashing schemes, for example the SHA-based Crypt proposed by Ulrich Drepper and used in some Linux versions.
A recurring theme here is to 'strengthen' or ...
5
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2answers
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What algorithms are best be cracked by GPU?
What algorithms are best being attacked by a GPU powered password cracker?
For example, I heard that md5crypt that is being used in unix shadow file, is not the best choice for GPU cracking because it ...
5
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4answers
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Brute force vs other methods of recovering passwords from shadow file
Do you know any good approach for de-hashing/actually bruteforcing hashed passwords in the shadow file?
On various operating systems, any good solutions/methods/programs.
Or is it better to upload ...
4
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2answers
789 views
openssl: recover key and IV by passphrase
A large amount of files were encrypted by
openssl enc -aes-256-cbc -pass pass:MYPASSWORD
Openssl should derive key+IV from passphrase. I'd like to know key+IV equivalent of that MYPASSWORD. Is ...
16
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3answers
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Is SHA1 better than md5 only because it generates a hash of 160 bits?
It is well known that SHA1 is recommended more than md5 for hashing since md5 is practically broken as lot of collisions have been found.
With the birthday attack, it is possible to get a collision ...
8
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6answers
553 views
Does prepending a salt to the password instead of inserting it in the middle decrease security?
I read somewhere that adding a salt at the beginning of a password before hashing it is a bad idea. Instead, the article claimed it is much more secure to insert it somewhere in the middle of the ...
8
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4answers
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moving from MD5 to SHA-512
This question is more of a security policy than a technical security question.
Many years ago I developed an asp.net site, implemented Forms Authentication, and stored the user passwords as MD5 ...
7
votes
6answers
558 views
Does repeating one word to form a password result in a similar pattern in its encrypted format?
If i use a single word to form a password by repeating it like the examples below:
securesecuresecuresecuresecuresecure
SeCuReSeCuReSeCuReSeCuReSeCuReSeCuReSeCuRe
...
7
votes
2answers
539 views
How does Google not care about “spaces” in Application-specific passwords?
I have recently setup "2-step verification" for my Google account.
One of the features is the ability to create "Application-specific passwords
" for devices that do not support the 2 step process. ...
6
votes
2answers
350 views
Implementing Secure Remote Password: Constructing the verifier
The SRP protocol as described in RFC 2945 generates the password verifier:
x = SHA(<salt> | SHA(<username> | ":" | <raw password>))`
v = g^x % N
I have three questions: why use ...
5
votes
8answers
675 views
Does truncating the cryptographic hash make it impossible to crack?
I store password hashes in their full value for example, $h = sha256('foo') outputs 64 characters: 2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae
I store that directly in the ...
5
votes
1answer
118 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 ...
3
votes
4answers
186 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 ...
3
votes
2answers
117 views
What steps can you take to make offline cracking of SRP harder?
In the aftermath of the Blizzard hack, what steps can I take to make offline cracking of SRP more difficult?
My question assumes that your database is already gone and that you implemented SRP more ...
3
votes
3answers
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Does the hash change the security of the Secure Remote Password protocol?
I'm implementing the Secure Remote Password protocol, and similar to this question, I'm wondering if I can use the SHA-512 hash function instead of SHA-1 currently being used. Would this help improve ...
3
votes
2answers
227 views
What is considered a reasonably high iteration count?
I copy-pasted a function that implements the PBKDF2 hashing algorithm in PHP. The function asks for the amount of time that I would want it to loop in order to produce a hash.
Now, I'm wondering, ...
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1answer
76 views
How big is the risk of hash fixed points/cycles?
It's established wisdom to hash password multiple times with a salt to increase the time it takes per brute force iteration. At the same time (unless the algorithm guarantees otherwise) there's a ...
1
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1answer
184 views
How to check for a key *and* store encrypted data?
I wish to create a system wherein I store encrypted data.
Users can access this data if they have the key. If they give a wrong key, they don't get access at all. If they give the right key, they get ...
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1answer
185 views
Of an efficient 16-bit checksum [closed]
Is there a way to make a 16-bit checksum of data with variable length, probably from 25 bytes to 8 KB?
The solution should be easy to implement, or should already be implemented in C++, and ...
