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

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246 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 ...
38
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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 ...
0
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2answers
32 views

SHA1 - S/MIME and CRL validity after deprecation?

In an internal PKI using SHA1 for hashing, will S/MIME signature and CRL/ARL signature be considered invalid in the next few years (SHA1 Deprecation) ? End certificates can be revoked, CA ...
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0answers
34 views

Is this PHP TOTP (time based one time password) idea sound?

Disclaimer: I am not very familiar with safety techniques in general. The problem: Quickly create lots of small files in server from a bash script. I used to use scp (secure copy) in order to create ...
0
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2answers
60 views

nginx recommended ssl_ciphers

I am looking for some advice on setting the ciphers for nginx with SSL. What would you recommend for a good compromise between security and compatiblity at the moment? I have made some research but ...
7
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1answer
471 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 ...
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1answer
97 views

How will SHA1 deprecation affect SHA1 roots in OS/Browser trust stores.

I understand the SHA1 deprecation policy applies to CA's issuing SHA2 end-entity certs and intermediates starting Jan 2017 but how will this policy affect the actual root certificates in OS/Browser ...
0
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2answers
87 views

Should I use HMAC in this situation

I need to store a big message encrypted on a server. What I am about to do is: Encrypt the message with a AES key; (Authentication) Hash the message with SHA512 and encrypt the hash with RSA priv ...
0
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1answer
133 views

Why are CA's now signing root certs with SHA2?

I see that CA's are now giving the option of having the root CA cert signed with SHA2. I have been told that the hashing function in a root has no security value, and is irrelevant as far as a ...
2
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3answers
92 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?
10
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2answers
236 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 ...
0
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2answers
196 views

What does 2^77.1 calls presented in a SHA1 attack mean?

Regarding the SHA 1 deprecation, I found this information here: http://blogs.technet.com/b/srd/archive/2013/11/12/security-advisory-2880823-recommendation-to-discontinue-use-of-sha-1.aspx I know ...
4
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1answer
155 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 ...
13
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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 ...
17
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3answers
2k 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 ...
2
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1answer
201 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 ...
1
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2answers
129 views

Why is the brute force search time for hashing algorithms 2^(num_bits / 2)?

I noticed that the brute force times (the time it takes to find a message that hashes to a given hash) of various hashing algorithms seems to be 2^(num_bits / 2). For example, people say that brute ...
2
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1answer
159 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
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3answers
253 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 ...
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4answers
75 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 ...
1
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0answers
40 views

How is this SHA-1 hash generated? [closed]

If you get a disposable email from say guerrillamail.com, and then fill out the forgot my password page at dahorta.org/app/index.php/cliente/resgatar_senha, it emails you a link to reset your ...
0
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3answers
145 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 ...
0
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1answer
65 views

Is it possible to distinguish between a SHA256 hash and an ecc256 key?

If an attacker were just given 256 bits, and they were either a SHA256 hash or a 256 bit elliptic curve key, would they be able to tell which one it is? Just out of curiosity, would they be able to ...
3
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3answers
292 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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2answers
900 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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1answer
137 views

What are the enhancements of SHA1 compared to MD5?

I am looking for enhancements of SHA1 when its compared to MD5. But I am not talking about just heap sizes. I am talking about different enhancements than heap size. Also, I think md5 is faster than ...
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2answers
499 views

Can NSA generate all hashes for rainbow table to break md5?

I was wondering about md5 encryption. It is good, and I agree that it is unbreakable. But this is why we have rainbow tables. What if bunch of people gather together and start brute forcing and ...
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2answers
574 views

Are RSA 2048, ECDSA, and the SHA uncrackable in the sense that AES-256 is uncrackable?

The answer http://security.stackexchange.com/a/25392 has seemingly shown that AES-256 will not be directly cracked for at least the next 200 years (unless we manage to harvest the energy output of ...
1
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1answer
131 views

Is hashing a DLL useful to protect from DLL hijacking?

I want to make sure that the dynamic link libraries used by my application can't be replaced with other libraries of the same name, in order to inject malicious code. Therefore, I thought about ...
4
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4answers
1k 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 ...
7
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5answers
9k views

nginx recommended ssl_ciphers for security, compatibility - with PFS

I'm currently using nginx with the following ciphers: ssl_ciphers HIGH:!aNULL:!eNULL:!LOW:!ADH:!RC4:!3DES:!MD5:!EXP:!PSK:!SRP:!DSS; I would like to maintain compatibility to older browsers, ...
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0answers
605 views

Do I keep my PHP simple auth session secure enough?

I'm experimenting with security, cryptography and web applications. My aim is to create simple login system that is realy secure enough. I'd like to share my approach to keep authenticated session ...
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1answer
94 views

MySQL authentication, how to pad the 20-byte salt

Im authenticating with a mysql server with the authentication method listed here. I observed the salt and hash using wireshark, and I know the password, but I am having trouble reproducing the hash I ...
2
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1answer
102 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 ...
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1answer
286 views

SHA1 Hash Find Salt

I have and android app that sends a encrypted sha1 salted message to a server, I know the message, is it possible to find the salt or it would be easier to try to reverse te android app?
0
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1answer
151 views

Is it possible to insert data into UUID?

Is it possible to insert arbitrary data into UUID? Let's suppose we have an MD5\SHA hash of something... can we encode that data into a valid UUID?
10
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2answers
598 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 ...
0
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2answers
157 views

Any reason to use bcrypt, pbkdf2, scrpt for other things than passwords? [closed]

Let's say I want to hash some data, using SHA256, in order to prove I know something. Maybe it's my secret ID for something. In the real of passwords we have moved from hashing -> hashing+salt -> cpu ...
1
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2answers
231 views

Use of pwgen with sha1 to create recreatable passwords

I'm looking at using Theodore T'so's pwgen (on linux/ubuntu) with its sha1 (-H) feature to generate passwords that I should be able to recreate later using the same file and seed. I briefly looked ...
1
vote
3answers
194 views

Hash algorithm without ASIC's

I want to design a new crypto-currency, with an algorithm which is different from SHA-256 or Scrypt. But in order to do this, I need to know the hash algorithm which is the hardest to make ...
0
votes
1answer
454 views

How secure is a partial 64bit hash of a SHA1 160bit hash?

So http://en.wikipedia.org/wiki/SHA-1 SHA-1 produces a 160-bit (20-byte) hash value and As of 2012, the most efficient attack against SHA-1 is considered to be the one by Marc Stevens with ...
0
votes
1answer
326 views

Can SHA-1 PRNG still create secure cipher keys?

I am concerned that a SHA-1 PRNG cannot produce an AES-256 cipher key with the expected 256 bits of security, or indeed any secure cipher key where over 165 bits of security are expected. The SHA-1 ...
3
votes
1answer
4k 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 ...
2
votes
2answers
119 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 ...
1
vote
1answer
621 views

Reversing a block hash of SHA-1 with known Plaintext?

Is it possible to reverse the hashing of a block in a Datastream fed to an SHA1 if the plaintext for that block is known? If it is not possible (which I assume) does it make attacks to retrieve the ...
0
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1answer
321 views

Challenge, Authentication and session key

I programmed an application on Linux using C, I added an authentication and cryptography layer that's going like this : 1 -client sends connection request. -server send a random challenge to client. ...
3
votes
2answers
627 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
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1answer
157 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 ...
0
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2answers
200 views

Why is SHA-3 (keccak) considered more secure than DES when you can attempt to crack it 3x faster? [closed]

Hash.Type....: descrypt, DES(Unix), Traditional DES Speed.GPU.#1.: 6215.8k/s Hash.Type....: SHA-3(Keccak) Speed.GPU.#1.: 20514.1k/s see: http://hashcat.net/forum/archive/index.php?thread-2085.html ...
7
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1answer
977 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 ...