Secure Hash Algorithm is a family of cryptographic hash functions published by NIST.

learn more… | top users | synonyms (1)

43
votes
3answers
4k views

Is Git crowdsourcing cryptographic attacks?

A strong cryptographic hash makes collisions unlikely. Many cryptographic protocols build on that fact. But Git is using SHA-1 hashes as object identifiers. So there are a lot of already computed ...
32
votes
3answers
72k views

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 ...
30
votes
2answers
3k views

What is the relationship between “SHA-2” and “SHA-256”

I'm confused on the difference between SHA-2 and SHA-256 and often hear them used interchangeably (which seems really wrong). I think SHA-2 a "family" of hash algorithms and SHA-256 a specific ...
18
votes
3answers
4k views

Is SHA1 weak for SSL?

I noticed that today after I scanned a site on the Qualys SSL Labs site that SSL ciphersuites which use SHA1 are now highlighted as being "Weak". It seems this has just happened; I scan sites pretty ...
13
votes
3answers
1k views

Trying to understand why signatures in root certs “are not used”?

Taken from here: Don't worry if the root certificate uses SHA1; signatures on roots are not used (and Chrome won't warn about them. Why are the signatures not used? Are not root certificates ...
13
votes
2answers
668 views

How safe are signed git tags? Only as safe as SHA-1 or somehow safer?

How safe are signed git tags? Especially because git uses SHA-1. There is contradictory information around. So if one verifies a git tag (git tag -v tagname), then checksouts the tag, and checks that ...
11
votes
1answer
592 views

Torrent “bad seed” attack by Sony, how does it work?

Sony recently saw a large amount of data stolen. In order to prevent the stolen data from being spread using torrents, they are doing what was called a bad seed attack. What is this attack? Is this a ...
10
votes
3answers
12k views

With ASIC bitcoin miners, should SHA256 be considered insecure for password hashing?

I'm sure everyone here has seen the rise and further rise of bitcoin. The process used for mining bitcoin is basically "let's brute force an SHA256 hash that is less than this amount" That being ...
10
votes
2answers
658 views

Password generation - too primitive?

A while ago (12 years old), I recognized my passwords weren't safe at all. Because I used the very same password everywhere, some grumpy admin could easily take over all my accounts (he got mail and ...
9
votes
2answers
2k views

“Official statement” on php.net : CRYPT_BLOWFISH is strongest hash algorithm. Why?

First: I asked this question on stackoverflow and was kindly asked to post this here again. See the original question here. According to the [early] doc pages of the new PHP 5.5 password ...
8
votes
4answers
5k views

HMACSHA512 versus Rfc2898DeriveBytes for password hash

We are currently using HMACSHA512 in .net, with a 128Char (64byte) validation key The salt is 64 char randomly generated string. We allocated 2048 length on the database for the hashed base64 string ...
8
votes
1answer
1k views

What's the hash for in ECDHE-RSA-AES-GCM-SHA?

Presumably the SHA is for deriving the AES key from the shared secret. Where else is the hash used? ECDH just does ECC (no hashing). RSA does masking and padding but this doesn't involve the ...
7
votes
4answers
3k views

Is sha-1 hash always the same?

Is it possible to ensure that a string is hashed always the same way no matter which language you use to do it (Java, vb.net... ) and no matter what operative system you are?
7
votes
1answer
588 views

Is there a method to get plain-text from cipher-text in HMAC SHA-1, given that the key is known?

This is technically not even an attack. We have all the resources at hand, except for the original plain-text. We have the cipher-text (to be converted back to plain-text), as well as the key. The ...
7
votes
6answers
763 views

Is leaking the hash of your encryption key a security risk?

I've been trying to design a simple archive format, that allows me to just bundle a bunch of encrypted files together. The idea, I currently have is to embed not the encryption key but a truncated ...
6
votes
4answers
1k views

Store password using sha1 [duplicate]

I've been using the sha1() function to hash password before inserting it into my database. But I have this procedure so that it just won't be the password to be hashed. My page would register a user ...
6
votes
1answer
7k views

Are there any known vulnerabilities in PPTP VPNs when configured properly?

PPTP is the only VPN protocol supported by some devices (for example, the Asus RT-AC66U WiFi router). If PPTP is configured to only use the most secure options, does its use present any security ...
5
votes
2answers
1k views

Security of Linux Full Disk Encryption (Ubuntu / Mint) -insecure?

I'm wondering, why is Ubuntu and Mint using SHA1 for Full Disk Encryption? I heard several times that SHA1 shouldn't be used anymore because it is weak and it could be cracked. Could you guys ...
5
votes
2answers
238 views

How is a hash's algorithm detected based on the hash?

I was reading an Ars Technica article this morning and came across the following towards the end (emphasis mine): Equation Group included six other hashes in different exploits that remain unknown ...
4
votes
6answers
1k views

Is there a table that compares hashing algorithms by speed, relatively (machine independent)

As far as I understood*, one of the major criteria when choosing a password / salt hashing algorithm is it's speed. To prevent brute force attacks, a slower algorithm is better (and also makes it more ...
4
votes
2answers
2k views

Why do most hashing functions produce hashes that have characters a-f 0-9?

This is something I never understood about hashing functions. I know that algorithms like whirlpool and blowfish both produce outputs that don't follow this pattern, but why is it that most do? Is ...
4
votes
4answers
3k views

Why does MD5 hash starts from $1$ and SHA-512 from $6$? Isn't it weakness in itself? [duplicate]

I have moved this question from stackoverflow to this place. I know it may be a question about 'opinion' but I am not looking for a private opinion but a source of the final decision to keep it this ...
4
votes
1answer
609 views

Firebug reports SHA-1 certificate error

For the script at the bottom of this post, Firebug reports the following error: This site makes use of a SHA-1 Certificate; it's recommended you use certificates with signature algorithms that ...
4
votes
0answers
53 views

Why did browsers deprecate 1024-bit RSA, but retain SHA-1?

I was reading Mozilla's security blog Phasing out Certificates with 1024-bit RSA Keys. Effectively, some browsers are deprecating 1024-bit RSA for CAs and Subordinate CAs because the certificate must ...
4
votes
1answer
188 views

How will SHA1 deprecation affect internal CA's?

I am hearing that the SHA1 Deprecation notices from MS/CHROME only apply to certs that are a part of a public trusted root program. This makes one believe that IE will have new logic built in to allow ...
3
votes
3answers
492 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
votes
2answers
2k 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?
3
votes
3answers
2k views

Will SHA1 of Email Addresses Always be Unique?

We want to store data about a person without storing their email address, but we want to latter connect that person with their data upon them supplying their email address. Storing a SHA1 of their ...
3
votes
2answers
739 views

Is it safe to expose an SHA1 hash of an encryption key?

Assume that party 1 and party 2 each possess a key used for AES encrypting data. Assume that the key was properly randomly generated and securely passed between them. Now I need a way for party 1 to ...
3
votes
2answers
276 views

Confidentiality and integrity for web session

When the client authenticates with our service, he is issued an opaque "token". This token includes the information, that identifies the client and some other information about the client ("payload"). ...
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 ...
3
votes
1answer
980 views

Replacing weak SSH fingerprint algorithms

Even though MD5 has been broken for years and its vulnerabilities have been used to create real-world rogue X.509 CAs and other horrible things, OpenSSH and PuTTY still use MD5 as the default public ...
3
votes
1answer
183 views

How signature validation would be checked on server side?

Sorry, It may be possible that few things are repeated in my question. I have gone through some documentation/discussion signing an API request and twitter signature documentation As per the ...
3
votes
2answers
608 views

Should I customize my Root CA's thumbprint/fingerprint? (SHA1 or MD5)

My goal is to make a certificate's thumbprint "easier" to verify, and not reduce security in doing so. Given that the RSA-based Bitcoin technology has a concept called a "Vanity address" where the ...
3
votes
0answers
37 views

Same version of Chrome, two different behavior regarding sha1 depracation [migrated]

i'm well aware of the changes made to Chrome 42 and sha1 signed certificates. Here a short reminder : https://blog.filippo.io/the-unofficial-chrome-sha1-faq/ Our client reported this problem and ...
2
votes
1answer
3k views

SHA1 hash encoded with base64 results not consistent?

When i take a hash of user input test123+ i get the following base64 result:- YaddchSU52yztwIMdtHzkg3p1oA= The results have been obtained using the online sha1 convertor I m failing to understand how ...
2
votes
3answers
314 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
votes
2answers
175 views

Easy protocol for email authentication

I'm cooking up a very simple system to send commands to a remote server via email. Everytime an email is sent to do_something@mydomain.net, the server runs a python script that does something ...
2
votes
1answer
831 views

what does GUID have that a whirlpool, md5 or sha2 hash dont

I'm trying to understand the use of GUID and what has always left me wondering is what's so special about them that I should consider using them instead of rolling my own type of unique id. In other ...
2
votes
1answer
1k views

Using John the Ripper to crack SHA hash w/ partial knowledge

Group, I have a SHA1 hash that I would like to brute-force. I have knowledge of several characters before and after the password (ie, if the hash is derived from "xxxpasswordyyy", I know both xxx and ...
2
votes
1answer
72 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 ...
2
votes
1answer
85 views

Truncating hash output for a unique ID

This seems like a common question, but my knowledge on hashing is very limited, so I'm looking for a more ELI5-type answer. I would appreciate if someone could help me with my questions Some ...
2
votes
3answers
143 views

GPG keys & SHA-1

I've heard that SHA-1 hashing is becoming less secure, and that most GPG keys are secured with SHA-1. Is there a way to determined if SHA-1 is in my GPG key, and what to do if this is the case?
2
votes
1answer
127 views

What to do with the extra bytes in ECDHE-RSA-AES-GCM-SHA?

I'm trying to implement, as an exercise, a protocol based on the cipher suite ECDHE-RSA-AES256-GCM-SHA384. As I understand things, ECDHE is used for the key exchange, RSA for the authenticity of the ...
2
votes
1answer
366 views

Python implementation of AES and SHA256/512 that are FIPS-140-2 validated?

For security purposes I need to use AES encryption and SHA256/512 in my Django/Python project. I know there are various libraries out there that provide different encryption methods but I can't seem ...
2
votes
2answers
133 views

How safe is Money Toolkit?

Money Toolkit is a smartphone app that can alert you to your balances and transactions across multiple accounts. I was reading their site and whether their practises are as secure as they claim to ...
2
votes
3answers
1k views

Preventing dictionary attacks against hashed passwords [duplicate]

Possible Duplicate: How to securely hash passwords? I have a website and on that website I use SHA-256 and salt my user's passwords. What I'm doing right now is padding each letter of the ...
2
votes
1answer
263 views

HMAC secret key for securing communication - how to keep private on DB

I have a mobile app that communicates to server over HTTPS. To authenticate the client and to make sure its who I believe it is, I return upon successful signup (apart from the username) a secret API ...
2
votes
0answers
41 views

How to create TLS SHA256 certificate request [migrated]

One of our business partners is requesting us to use a TLS SHA256 certificate to connect to their APIs. I am not sure how to generate these requests. I have used openssl in the past to create these ...
2
votes
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 ...