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

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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. ...
0
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2answers
146 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
99 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 ...
-3
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2answers
244 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 ...
1
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2answers
221 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 ...
2
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1answer
2k 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
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3answers
1k 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 ...
1
vote
1answer
82 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 ...
2
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4answers
298 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 ...
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4answers
2k 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 ...
1
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0answers
176 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 ...
1
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1answer
70 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
79 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 ...
-1
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1answer
139 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
133 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?
6
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3answers
2k 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 ...
10
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2answers
565 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
134 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
164 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 ...
0
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3answers
145 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 ...
6
votes
1answer
670 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 ...
0
votes
1answer
292 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
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1answer
227 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 ...
0
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1answer
2k 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
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2answers
106 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
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1answer
476 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
234 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
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2answers
539 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
133 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
181 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 ...
3
votes
2answers
358 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 ...
1
vote
1answer
171 views

Generate Keytool Object from CSR

I have to develop an application which uses another application for generating a CSR. After generating the CSR I have to provide this CSR along with a SHA256 hash of the public key to a CA. The ...
26
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3answers
39k 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 ...
8
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1answer
1k 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 ...
0
votes
1answer
1k views

Using JTR to crack Skype Passwords

The scenario: coworker's Skype somehow lost his auto-fill password. He doesn't remember it anymore, and the account is hooked up to an email address that no longer exists. He's never purchased any ...
7
votes
3answers
10k 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 ...
1
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1answer
372 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 ...
0
votes
3answers
3k views

Is it possible to get the encryption key when you have the plaintext?

I have a question about SHA256. I know that this algorithm was used to encrypt a text, which I have. I also have the encrypted version of this text. My question is, can I somehow get to the encryption ...
7
votes
6answers
563 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 ...
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5answers
668 views

create a variants of MD5

I have also asked similar q here : To create a variants of MD5, I made following changes : MD5 uses a non-linear sin(i)* pow(2,32) ----> i plane to use cos(i)*pow(2,32) Instead ...
3
votes
2answers
218 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"). ...
6
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4answers
1k 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?
1
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4answers
243 views

Is it possible to know the key if we have the original value and the hash using HmacSHA1?

I was wondering if it were possible to know the key if you already know the original value and the hashed result. For example, let's say : `$value` = helloworld `$hmac_key` = 0123456789 `$result` = ...
3
votes
2answers
1k 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 ...
2
votes
1answer
833 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 ...
1
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2answers
199 views

Creating a rainbow table with predefined text

I need to extract a password from a hash. This hash was generated by prepending and appending two different predefined strings to the password: Hash(PredefinedString1+Password+PredefinedString2) ...
2
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2answers
148 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 ...
1
vote
5answers
854 views

Is SHA-1 encryption?

I have read that SHA-1 is a cryptographic hash function. On an exam, SHA-1 was given as a possible one-way encryption algorithm. Does SHA-1 require a key as input? Is a key required to qualify as ...
0
votes
1answer
799 views

X.509 certificate attack (small sha1 private key)

I've got a X.509 certificate, created by an unknown CA. The only thing I know is that the private key is very short, so I can retrive the private key. Is there any program I can use? The used ...
3
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6answers
662 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 ...