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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Is it worth it to implement both SHA2 and SHA3 at the same time?

I'm creating a password storage system for a web server I'm building for fun. Would it be more secure for me to use both SHA2 and SHA3 for hashing, and then store them in a database? If I use both ...
0
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1answer
38 views

Can XOR be used in a Merkle Tree instead of concatenation?

I am trying to understand why, in a Merkle Tree, the concatanation between hashes is used - and not for example the XOR operation. Can they be considered the same for the purpose of a Merkle tree? I ...
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0answers
32 views

What is the format of PDF hash?

When I use a tool like pdf2john.py from John The Ripper on an encrypted PDF, it gives me an output like: ...
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1answer
46 views

What hash algorithm is Disqus using now for users' emails? [on hold]

Disqus previously used the MD5 algorithm to hash users' emails. A group of Swedes used a dictionary attack to reveal the email addresses (and in many cases identities) of hundreds of Disqus users, ...
2
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0answers
12 views

CMS/PKCS#7: specifying signatureAlgorithm with digest?

I'm confused about algorithm selection for Cryptographic Message Syntax (a.k.a. CMS, PKCS#7) signed objects (RFC5652 Section 5.1). The SignerInfo structure (RFC5652 Section 5.3) has two separate ...
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0answers
37 views

Designing a security system for road pricing

It's my first semester with Information Security and I still feel a little lost. Sorry in advance for stupid mistakes I may have made. the examples in round brackets below are my own ideas, wrote ...
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1answer
39 views

What kind of hash is this? [closed]

What kind of hash is this, wherein there's a hash and there's a key with it? eg., fe9387012723dcc0f91c687130fcce6e:lreto Is that Blowfish or something? e_e I'm just asking whether these kind of ...
5
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6answers
175 views

Is hashing a string a secure manner for generating passwords?

I have several servers that I'm using for an online business. I have passwords for MySQL, Wordpress, SSH, FTP, Domain Provider, Paypal, and many more. I wanted to have a different, very long password ...
5
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3answers
415 views

Any reason not to encrypt a 32 byte value by XORing it with a PBKDF2 hash?

Ordinarily I'd use PBKDF2 to generate a key which i'd use with AES. But seeing as the hash is going to be as long as the data I need to encrypt is there any disadvantage to just XOR'ing it? My ...
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3answers
35 views

What type of hashing method is used for the private key to encrypt for signing messages?

To use RSA for signing, Alice takes a hash of the message, encrypts the hash using her own private key, and appends the result (this is the signature) to the message. Eve can of course still ...
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0answers
44 views

What algorithm is being used? I have the input and the output here [closed]

would really appreciate a genius at work here. Input: ABCDEFG-1D3B Output: xvn0qEeftqyrkG52 What algorithm or hash is being used to create the output from the given input?
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2answers
105 views

Would my protocol be safe?

Suppose I have a protocol like the one below between users A and B; -A sends random nonce G1 to B -B sends back hash_k(G1) and random none G2 -A verifies hash_k(G1), then sends back hash_k(G1 | ...
4
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3answers
130 views

Secure Hash of a very short payload - is it possible?

I am looking to verify the integrity of a very small payload, approx 64 bytes, which will be stored in a QR code. I need to verify that the payload has not been generated or altered by an attacker. ...
0
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0answers
29 views

Understanding the application of hashes, HMACs, and KDFs

I think that I understand the right application cases for the following crypto functions, but I'd like to confirm my understanding and also propagate the safe use of crypto throughout the intertubes. ...
2
votes
1answer
42 views

Is there a benefit of using stateless JWT over SHA256 hash for API tokens?

Does it make sense to use stateless JWT (without persistent storage) over plain SHA256? Example scenario: User logs in User token generated as follows: a. JWT.encode(userId, 'secret') or b. ...
1
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2answers
81 views

Is it possible to crack hash with known salt? If yes how?

Hello folks, I was wondering , if the salt in the hash is known to us,then is it possible to crack to extract the password from the hash? If Yes, How?
2
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3answers
110 views

Can I initially hash passwords with SHA instead of hashing them with bcrypt to decouple requests from slow crypto functions?

I'm using bcrypt for some web service requests that hash multiple passwords. The problem is that these web service requests can take minutes to complete due to bcrypt. Not very user friendly. My ...
2
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5answers
151 views

Does publishing the md5sum of a private key compromise the private key in any meaningful way?

If I have a 4096 DSA private key used for signing binaries, and I want to ensure that a partner has an identical server using the same private key, can I send the md5sum of the private keys over an ...
19
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3answers
2k views

Why are MD5 and SHA-1 still used for checksums and certificates if they are called broken?

I was just reading about SSL/TLS stuff, and according to this site (which is rated as A by Qualys SSL Labs), MD5 is totally broken, and SHA-1 is cryptographically weak since 2005. And yet, I noticed ...
1
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1answer
46 views

Are multiple applications of a salted Linux MD5 hash easier to break than one? [duplicate]

I have hashed the same password a lot of times (approximatively 1000 times) using the salted Linux MD5 format. I want to know if it's easier to recover the cleartext password or not. Is there ...
2
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1answer
52 views

What is the best way to store passwords in OpenLDAP?

I would like to store user credentials in an OpenLDAP or similar directory server. A lot of online commentary about storing passwords in modern contexts recommends using password derivation schemes ...
9
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2answers
653 views

Should password reset tokens be hashed when stored in a database?

Passwords are hashed so that if someone gains access to a database of passwords then they won't know what the actual passwords are and so they can't log in. If I can get a valid password reset token ...
3
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1answer
125 views

Is this symetric or asymetric encryption?

I’m at the beginning of my journey into the world of security. I am reading about the most fundamentals topics and I have encountered something unusual that has thrown me. The Conundrum: I have come ...
2
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1answer
158 views

This is 2015. Has SHA1 been exploited or cracked yet?

went to Qualys SSL lab and tested one web site. One of the findings says the site is signed with weak algorithm SHA1withRSA and I did some research all are saying we should change to SHA-2. may i know ...
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2answers
47 views

Secure encrypted storage of values that allows DB lookups?

I'm developing a system that has to store Finnish national identification numbers as securely as possible while allowing "does this identification number exist in the system?"-type queries over a web ...
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0answers
66 views

how many sha1 hashes per time on current hardware [closed]

How many sha1 hashes per second can current hardware (say a 500$ gpu) compute, when the input is 256 byte long? (or any other length). The question behind is how long (or how costly) is it to mount a ...
0
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1answer
60 views

MySQL Database Password protection

I am developing an industry-level web server that requires that all passwords be encrypted in some way. The middle-ware for the server is Java-based. My only restriction is that I can't use API's ...
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votes
2answers
87 views

If I were to perform a MD5 hash every microsecond from 1-1-1970 how many hash colisions would I have [closed]

I mean with a standard length of 32 you are doomed to have some hash collision, I ask this question just out of curiosity. I havent put a supercomputer or a timemachine just yet.
3
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2answers
680 views

Decoding SHA-512 value

How does the SHA-512 decoder on the following page work? http://md5hashing.net/hashing/sha512#main Hash values supposed to be unable to reverse. Is this page fake?
5
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1answer
84 views

How does combining SHA256 with RIPE-MD160 compare to SHA256 + SHA-3?

Bitcoin stores its addresses as a combined SHA256 + RIPE-MD160 hash. Is it correct to assume this is done to prevent a failure in the algorithm? Since SHA3 was designed to be an alternative to ...
2
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0answers
42 views

How does SHA3 (Keccak & SHAKE) compare to SHA2? Should I use non-SHAKE parameters?

Keccak is the winner of the SHA3 competition. Since Keccak is highly customizable (presumably for security/memory/time/speed tradeoffs) there does seem to be some controversy around how Keccak ...
2
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1answer
73 views

Hashing algorithm for cryptsetup

I will encrypt my SSD using cryptsetup and I would like to know which hashing algprithm to use. First of all, cryptsetup benchmark: PBKDF2-sha256 262144 iterations per second PBKDF2-sha512 ...
2
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1answer
71 views

Securely storing passwords using PHP5

Starting note: After going through some articles and answers posted on SO related to storing secured passwords I'm still not sure whether my way of thinking is applicable to todays reality. I'm ...
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2answers
55 views

Salt addition in hashing? [duplicate]

I may be wrong here but reading about salt I was wondering whether if we use the same salt for every password saved in our database won't users having same password would lead to same hash even after ...
0
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1answer
98 views

How does PHP's password_hash() BCRYPT cost factor translate into cracking computation times

I am trying to fully understand the relationship between BCRYPT's COST factors and how much more time it would take a machine to crack a password with PHP 5.5's password_hash() The encryption times I ...
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0answers
9 views

Does a static salt in addition to a random one add any security? [duplicate]

I'm looking through some old hashing code and found something that made me raise an eyebrow. In order to store passwords, it uses BCrypt to generate a random salt and hash the password. Before that, ...
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2answers
158 views

SHA256 to text or MD5

I want to decrypt a sha256 to text. Is there a way other than bruteforcing to decrypt sha256? Like if I convert that SHA256 to MD5 and then try decrypting?I know its hard and the possible way for ...
3
votes
2answers
136 views

Is there any reason for using private key 2 times when creating security hash?

One of the payment solutions for the websites provides the following way of creating security hash for payment link: hash = sha1(private_key + payment_params_json + private_key); Is there any ...
4
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0answers
69 views

Random padding in hash functions

In this answer, it was recommended that you add random padding when hashing messages for a trusted timestamp, such as for predictions, in order to avoid dictionary and brute force attacks (at least ...
2
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0answers
51 views

Disallowing Similar Passwords [duplicate]

Upfront, I want to clarify that I am not a professional cryptographer, I am more curious about playing with the math and science behind it, and also want to improve my habits with my own personal and ...
0
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2answers
229 views

How hash ensure integrity of data? [duplicate]

I understand what a hash is, basically we calculate a hash and append it to the message and send it to the receiver. If someone alters the message, the receiver will know because there would be a ...
1
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0answers
42 views

Hashcat Turkish character problem [closed]

I'm using cudahashcat, it haven't special chars like "öçşĞÜ" in standart charsets. I defined charsets with windows-1254 and other encoding types(and -1 öÖçÇğĞşŞüÜıİ?a parameter), i tried but they ...
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1answer
43 views

What is the most secure way to protect a custom CMS from infiltration? [closed]

I have a custom CMS with a randomly generated ASCII 100-character string from this site for both my username/password. I also have this following sha512 encryption system, which was created by ...
0
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2answers
126 views

Is my hashing function good enough

Is there an obvious flaw with this hashing function (written in PHP)? function hash($password) { sleep(1); // Make hashing slow $hash = ""; $iterations = strlen($password); for ( $i = 0; $i ...
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1answer
80 views

Disastrous aftereffects of a hashing attack

I am writing about hashing functions for my thesis. I want to know whether there were disastrous aftereffects of a successful hashing attack in history and what kind of hashing attack was used. ...
1
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1answer
86 views

John the Ripper missing formats [closed]

I have an sha256 hash that I am trying to crack with John the Ripper. However, it doesn't recognize raw-sha256, raw-md5, or any hash format other than descrypt, bsdicrypt, md5crypt, bcrypt, LM, AFS, ...
31
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5answers
6k views

If a web site shows me what my password was changed to, is it stored as plain text?

I just changed the password on a school-related web site. After completing the change successfully, the next page showed what the password was changed to. Can I conclude from this that the password ...
1
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2answers
65 views

Is it known to what message size are standard hash functions injective?

This simple Python script verifies that all messages of length 1 have different SHA-1 hashes: import hashlib s = set() for i in range(256): s.add(hashlib.sha1(chr(i)).hexdigest()) print len(s) ...
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0answers
36 views

Is there any merit to the RFC 3414 (SNMPv3 User Security Model) password-to-key method?

RFC 3414 (published 2002) specifies a method of generating keys based on password in its Appendix, which essentially takes any "passphrase", and keeps on repeating it until there is a 1MB string, at ...
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0answers
56 views

PKCS#7 signed data structure in signed PDF document

Is it mandatory to include PKCS#7 data (OID 1.2.840.113549.1.7.1) octet string into the sequence of PKCS#7 signed data? I mean if you want to sign PDF, you are basically adding PKCS#7 container ...