Cryptography is the practice and study of logical means used to achieve information confidentiality, integrity and authenticity. It covers, among other things, encryption (making some data unreadable except for those who know a given secret element, called a key), data hashing (in particular for ...

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Verifying Authenticode signed executables and DLLs using OpenSSL API [closed]

I have installed openssl and now the rsa_test.c is running fine. What I want to do is: Open any exe or dll digital certificate. Extract the Thumbprint and PublicKey. The public key contains the ...
5
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1answer
278 views

security issue on storing keys and certificate on token

I'm creating a sample USB token with Atmega64. As I have to store both the public and private key and the certificate on my token is there any important security issue that I should worry about, ...
3
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2answers
575 views

Distributed XAdES-X and XAdES-A signatures over multiple documents

As the standard is not completely clear in this matter, I'm trying to found out if the XAdES standard (ETSI TS 101 903 v1.4.2) describes distributed case in which the SigAndRefsTimeStamp element or ...
3
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4answers
4k views

What Are The Best Practices (Application Security Policy) For Modifying Rijndael Salt, IV, Pass Phrase

(Note: originally posted in SO - advised to post on SSE) With regards to Rijndael encryption, what (if any) are the best practices (and consequences) regarding the periodic modification of one or ...
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5answers
823 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 ...
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2answers
805 views

encryption method against man in the middle attack

Let's say there are 3 computers: Alice, Bob, Carol. Carol is network provider, so everything from Alice to Bob and vice versa passes through Carol. Carol can modify messages between Alice and Bob. Is ...
6
votes
2answers
2k views

Should we start using SHA-3? [duplicate]

Possible Duplicate: What is SHA-3 and why did we change it? SHA-3 has been finalized! So, what does secuirty.se think about the new hash funciton? Should we start replacing all uses of ...
3
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2answers
2k views

Using Elliptic Curve Cryptography

I am wondering if ECC could be used the way that the data is encrypted with the public key instead of the random generated key. Is there any advantage doing that comparing to the "traditional" way of ...
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4answers
2k views

Tool for public key cryptography where password is the private key?

Is there any free & open source tool for public key cryptography, where the private key is just a chosen password? Here is what I need: I want to make backups every hour using a script I want ...
4
votes
2answers
3k views

Shared Secret, is it a public key or a private key?

Reading the Diffie-Hellman non mathematical explanation i found that some mathematical operations are performed on private-key and the recipient's public key to generate a "shared secret" on both ends ...
11
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1answer
609 views

XKCD #936: under what assumptions is 1000 guesses/second over a network plausible?

In XKCD #936, a rate of 1000 password guesses/second is proposed as a "plausible attack on a weak remote web service". Under what assumptions is this rate plausible? It seems much too high to me. I ...
3
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1answer
210 views

What are the benefits of federated identity management over bare bones public key encryption?

What are the main reasons for having a federated identity system such as OpenID over having identities based purely on a public key? OpenID uses an Identity Provider to confirm that a user owns a ...
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votes
3answers
475 views

find password and iv of an encoded string knowing the decoded string

If I would know the clear and encoded versions of a string could I somehow find the password and.or iv that wore used to encode it? Encoding done with open_ssl aes-128-cbc.
11
votes
1answer
8k views

Where is the salt on the OpenSSL AES encryption?

I'm interested in knowing how and where OpenSSL inserts the generated salt on an AES encrypted data. Why? Im encrypting data in Java classes and need to guarantee that I can use OpenSSL to decrypt ...
4
votes
1answer
174 views

Computational Feasibility of finding 'Good Links' of the following format

I recently stumbled upon this and am checking here to see if what I am proposing is indeed feasible and can be considered a breach of privacy. For obvious reasons I am not revealing the website ...
3
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2answers
3k views

Best practices for TrueCrypt + Yubikey combination

I'm trying to find a secure and convenient way to encrypt my external disk with TrueCrypt. Currently I use a 50 character strong password but I'm tired of typing it every single time. I have a Yubikey ...
4
votes
1answer
77 views

Standards for CA cert revocation and time-constrained cryptographic algorithm parameters

I'm working on software that will be in use for foreseeable future (15 years+) that will need to validate XAdES-A signatures (long term archival, similar to PAdES-A, but for XML). That means, it will ...
19
votes
4answers
2k views

NSA Suite A Cryptography: Security through obscurity?

What is the opinion of scholars, cryptographers on NSA Suite A? Containing unpublished algorithms. Could it really be that much better than the published algorithms besides being obscure and not ...
3
votes
2answers
373 views

Why is Elliptic Curve Cryptography not used much outside of government? [closed]

It seems that Elliptic Curve Cryptography, being required by the US government, is not being used outside of the government. Why is this? And why does the government support it's use for government? ...
20
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2answers
3k views

Is HTTP compression safe?

The CRIME attack taught us that using compression can endanger confidentiality. In particular, it is dangerous to concatenate attacker-supplied data with sensitive secret data and then compress and ...
3
votes
1answer
195 views

CMC (RFC 5272) compatible CA server

I need a CA server or any tool that supports Certificate Management over CMS (CMC) format, described in RFC 5272 (RFC 2797). I need a possibility to generate different Full PKI requests and responses ...
0
votes
1answer
285 views

How key_derivation and key_verification functions are implemented of a 7-zip archive's encryption mechanism?

I am curious about how password recovery works for password protected files. And I want to know the exact flow of the 7-zip encryption mechanism :) !! 7-zip uses the AES-256 encryption algorithm in ...
1
vote
1answer
277 views

Can I combine two of SHA-3 candidates cryptography hash functions and obtain more secure Algorithm? [duplicate]

Possible Duplicate: Are different hash algorithms ever used together? For example, Is possible to combine (Concatenate or Chain or XOR) Skein SHA-3 candidate with Grostl SHA-3 candidate to ...
3
votes
2answers
648 views

What risk does commoditized dedicated SHA256 processors pose to IT Operations?

With the advent of GPU-based computing, and now commoditized/dedicated SHA256 processors, what risk does this hardware pose to cryptography? What security algorithms should be closely watched or ...
1
vote
2answers
992 views

Diffie-Hellman key-exchange: securing prime and base

As we know DH algorithm based upon 2 large prime numbers, which are used to be called as prime and base I am writing app which implements DH key exchange algorithm. From security point of view should ...
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2answers
3k views

Estimating the size of a rainbow table

What are rainbow tables and how are they used? Gives a very precise answer about what rainbow tables are and how they are used. I had always confused hash-tables and rainbow tables. My question is ...
14
votes
4answers
4k views

Generate cryptographically strong pseudorandom numbers in Javascript?

Is there any good way to generate cryptographically strong pseudorandom (or true random) numbers in Javascript? The crucial requirement: if a.com's Javascript generates some random numbers, no one ...
4
votes
1answer
4k views

Is PBKDF2 only SHA1 in C#?

I can't find a way of specifying the hashing algorithm used by the PBKDF2 (the Rfc2898DeriveBytes class) implementation in C# System.Security.Cryptography. It seems to be just SHA1. Am I missing ...
15
votes
1answer
11k views

How should API keys be generated?

I want to make sure requests can't be forged and sent on to my server. In order to do this I need to generate an API key per user on my system. The purpose of the key will be to sign requests on the ...
3
votes
1answer
96 views

SSL Based Denial of Services due to Message Digest

On a very high level, its known that SSL/TLS uses message digests to verify the integrity of the messages sent. However, the question I have in mind is : How does SSL ensure a DoS does not happen ...
30
votes
3answers
65k 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 ...
3
votes
2answers
383 views

Distributed md5 crack software?

I'm studying about cracking password using brute force, and in my way I found softwares like John the Ripper and MDCrack, that works really nice, but are restricted to one machine. There is some ...
4
votes
4answers
919 views

Is asymmetric encryption ever recommended for long-term storage?

Is asymmetric encryption ever recommended for long-term storage of data, is it advisable for example to store data in a database such that: 1) A user enters data on a website, it is encrypted using a ...
4
votes
2answers
392 views

From password to key

Can you explain this passage from Wikipedia? When a password (or passphrase) is used as an encryption key, well-designed cryptosystems first run it through a key derivation function which adds a ...
8
votes
5answers
1k views

How do RSA fingerprints protect from MITM attacks?

I understand that RSA fingerprints are used to verify that you are really connecting directly to who you want to connect to, and not someone else posing as that site. Like when you do a git push, it ...
7
votes
3answers
467 views

How secure is HTTPS with weak ciphersuites?

Today I came across the website https://mtgox.com/, which claimed to be secure because of the Verisign certificate. I checked the certificate out of curiosity (it's the first thing they claim, let's ...
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votes
2answers
125 views

Should I use salt to authenticate data?

I have a client and a server. The client makes a request containing userId, cardId, position (on the card) A hacker could just do the same http request with the next position. So I think about ...
5
votes
2answers
287 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
4answers
1k views

Asymmetric crypto: Decrypt own messages without having private key

I have built a messages system for my website. Users can send the admin messages which are stored in the DB after being AES-encrypted. I think that using asymmetric crypto (RSA through openssl) ...
8
votes
4answers
5k views

HTTP Basic auth password storage more secure than Digest auth

If you are using SSL already, it appears Basic auth is the way to go since you can perform bcrypt with the password when you store it in the database, where as Digest auth only allows md5. As we know, ...
8
votes
1answer
1k views

What is a cryptographic puzzle?

On the wikipedia page on TCP under Denial of Service the following paragraph is found: By using a spoofed IP address and repeatedly sending purposely assembled SYN packets, attackers can cause ...
6
votes
8answers
2k 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 ...
3
votes
6answers
295 views

Is it okay to wrap a cryptographic hash with MD5 for storage?

Is there any security issues if you wrap your cryptographic hash with MD5 for storage purposes? For example: $hash = md5(hash($password,$salt,$rounds)); Note: hash() uses scrypt or bcrypt or pbkdf2 ...
4
votes
4answers
718 views

Can public keys be a security risk when performing password-less SSH logins?

Some companies use monitoring software such as nagios or icinga. In order to perform checks on the servers, they often need password-less SSH logins. The servers being checked put the public key of ...
55
votes
5answers
8k views

Why shouldn't we roll our own?

Why shouldn't we create our own security schemes? I see a lot of questions around here about custom crypto and custom security mechanisms, especially around password hashing. With that in mind, I'm ...
2
votes
2answers
1k views

Is there an index of all md5 collisions?

I am about to build a caching system based on md5 to generate file names out of lists of natural numbers. The inputs would be groups like: 1,18,94,100,266,1854. I know there are some collisions in ...
5
votes
3answers
3k views

How insecure are PHP's rand functions?

There are some pseudo-random-number generators in PHP: rand(), srand(), mt_rand(), mt_srand(). You can look at their code here. I understand those functions are insecure, but how insecure are they? ...
15
votes
4answers
496 views

Why aren't digital signatures the standard way to authenticate web clients?

The web is a mess of incompatible cookie schemes, asinine requirements ("your password must contain letters, numbers, and at least one symbol from !()-_., and must begin with a letter, and once you ...
60
votes
5answers
18k views

Is sending password to user email secure?

How secure is sending passwords through email to a user, since email isn't secured by HTTPS. What is the best way to secure it? Should i use encryption?
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1answer
7k views

Encrypting string in javascript and decryption in java

I would like to know if someone know any library to do encryption in javascript and decryption in java. I have already tried many API, But getting not not getting same values in java. I want ...