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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The security level in hash function

What is the difference in security between using part of message digest hash function or all the message digest hash function? and is there any equation can calculate the security for part or whole ...
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2answers
2k views

Is it reasonable to prevent timing attacks by using fixed processing time

I have systems that perform cryptographic operations within a SSL/TLS tunnel. My concern is that I may leak timing information when encrypting, decrypting, or hashing. Part 1 Is it a good idea to ...
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2answers
460 views

Securing Time Sensitive Data

I have a number of time sensitive, embargoed pieces of information that I need to distribute over the Internet and have received at a precise time. I'm currently dealing with the problem by uploading ...
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1answer
2k views

sha-512 vs sha-3? [duplicate]

Does the new SHA-3 Keccak hashing algorithm offer any benefits from SHA-512? "Even worse, none of the SHA-3 candidates is significantly better. When SHA-3 is announced, I'm going to recommend that, ...
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2answers
9k views

Why does OpenSSL not include AES-256-GCM? [closed]

I'm trying to implement AES-256-GCM in Ruby. Ruby's OpenSSL wrapper library and aead library both clearly seem to believe that OpenSSL itself supports this. However, neither 0.9.8r (which I had ...
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4answers
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Is using the md5 hashing algorithm as method for authorization in an HTTP POST request unsafe?

I am creating a page on a website that will show a user some authorized information from another website, and that website uses a combination of the user's user-number and a secret passphrase hashed ...
0
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1answer
163 views

Securing the SOAP Messages

One of my clients wants to encrypt few sensitive information which will be transferred through webservices / SOAP. My client has the following suggestions: Encrypt the sensitive data with AES 128-...
3
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1answer
4k views

aes cfb 128 decryption /encryption problem between Erlang and PHP

Update 2 - it works Thanks to Tom Leek for his answer. The CFB mode of mycrypt for Rijndael uses a 8-bit feedback loop and not a feedback loop the length of the key/iv. You have to force it to use ...
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3answers
608 views

Use of rainbow tables with the NY Times hack?

The NY Times recently published a story about how they were hacked during a four month period. The hacks allegedly were carried out by part of the Chinese military. One part of the story that ...
2
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2answers
192 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 ...
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4answers
1k views

Can an attacker reuse stolen SSL private key to recreate that domain on his server

Say my domain (https://example.com) SSL private key has been stolen and was not protected by a passphrase then. Can the attacker uses that key and certificate to host the same domain on different ...
4
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2answers
3k views

What are the differences between ssh generated keys(ssh-keygen) and OpenSSL keys (PEM)and what is more secure for ssh remote login?

I have learned there are 2 methods to make SSH remote login easier and secure , those are; ssh generated keys (using ssh-keygen)OpenSSH Keys PEM (.pem) keys usually generated with OpenSSL (Amazon ...
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2answers
731 views

What is the best way to generate keys in phpseclib?

I am using phpseclib implementation AES and HMAC. But I dont know the best way to create random keys for these. What is the best way to do? Is there any built in function in phpseclib to create keys ...
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2answers
3k views

What is the difference between protocols and algorithms? [closed]

I am learning network security and I can't understand the boundary line between protocols and algorithms. Are algorithms the concrete realization of the protocols? Are protocols composed of several ...
2
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6answers
2k 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 "...
3
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4answers
2k views

SSH: reusing public keys and known-man-in-the-middle

Usually, people recommend to use a single private-public key pair everywhere (if we're not talking about a possibility of compromising the private key): Best Practice: “One per-user ssh key” or “...
0
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3answers
255 views

Maintain sensitive key between requests

EDIT: Reworked question. Previous version too poorly asked. On my website users write sensitive messages that must be kept secret. The entire user area is over SSL, so the communication between user ...
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1answer
257 views

Tracking information on HTTPS connection

My organization uses cyberoam firewall. They are monitoring all activities including my search text in Google, Wikipedia etc. So recently i changed to HTTPS versions and now using HTTPS connections of ...
0
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1answer
1k views

Is TLS secure when full eavesdropping on the network occurs? [duplicate]

Possible Duplicate: How is it possible that people observing an HTTPS connection being established wouldn’t know how to decrypt it? Alice connects to Bob's site via a TLS secured connection (...
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3answers
2k views

Hash Function Xor

For a hash function what is the best secure method, XOR or Concatenate: h(data1 XOR data2 XOR data3 XOR data4) ? or use h(data1||data2||data3||data4)?
3
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1answer
204 views

Updating stored, encrypted containers on a server

My scenario is this -- I want to store an encrypted container on a network server. This encrypted container should be accessible to others to download and decrypt/mount locally provided they have the ...
5
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1answer
191 views

Detecting PRNG Use from Output

Question: Is there a way to detect the use of a PRNG strictly from observing the output provided by an application? Background: During an audit of a key generating algorithm that I knew was based on ...
3
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1answer
572 views

Kerberos realm understanding

Could someone summarise why realms are necessary in Kerberos and the advantages of the concept. I'm struggling to isolate everything I know / beginning to understand into some well defined points for ...
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3answers
3k views

Is a 512 bit RSA key secure when used temporary?

Is a 512 bit RSA key secure when a new key gets generated and used approximately once a week? The key is only used for signing messages, not for encrypting sensitive data. This is for a system where ...
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2answers
465 views

Can I use hardware token OTP to stop piracy?

Our firm sells an offline desktop (.exe) software, we are thinking of using OTP (from hardware token like in internet banking) to stop people from copying the software without permission. Basically, ...
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2answers
4k views

how strong is AES without salt

The AES cryto library provided to us from company, does not generate a different encrypted value for plain text. If text is "abcd" , it will generate the same encrypted value over multiple iterations....
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1answer
750 views

Storing Private Keys Generated on Server with specific User's Password Securely

I am currently building a system (PHP Web Application Framework) that creates an RSA Key Pair for a user to allow other users to send secure information from one to another. The public key is ...
6
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1answer
763 views

Can I re-use another vendor's dual factor token in my own system? (Avoid physical token bloat)

I read the open source multifactor authentication techniques called HOTP RFC 4226 and TOTP RFC 6238 and realized that a single random number is the basis for the token's cryptography... and that this ...
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2answers
69k views

Security comparsion of 3DES and AES

Which one is more secure and least possible to be broken through cryptanalysis AES or 3DES (no matter performance)? I need to use encryption for my projects to store and secure sensitive information ...
2
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1answer
944 views

How does the YubiKey Validation Server work from an encryption perspective?

Many YubiKey servers rely on the free cloud hosted authentication that comes with the product, but I'm interested in keeping all cryptographic material in my control. For that reason I am looking at ...
4
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1answer
274 views

Combining MAC and Encryption

What is the most preferred and secure way of combining both Encryption and MAC. There was a lecture on different combining strategies adopted by different protocols on a cryptography course by ...
6
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1answer
2k views

OpenVPN Why CBC mode is recommended?

I just set up my installation of OpenVPN on my server. I am curious why the OpenVPN manual recommends CBC mode. I heard that CBC is predictable and not secure; is that true?
1
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1answer
136 views

Reasonable computationally lightweight security?

I've read a bunch about how one should use bcrypt or PBKDF2 as a good middle ground between tunable workload and acceptable time to make brute force and collision attacks unfeasible. What if the ...
25
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7answers
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At what level of abstraction should a developer work with with regards to cryptography?

I have recently came across an old blog post by Jeff Atwood which got me thinking. What could be easier than a EncryptStringForBrowser() method which has security and tamper-resistance built in, ...
3
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0answers
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Is the use of JavaScript for cryptography ever appropriate in the browser? [duplicate]

Possible Duplicate: How secure is aSSL (javascript)? Does it effectively mimic SSL? After some searching around, I realized we don't have an easily visible canonical question about this on IT....
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3answers
4k views

KDC(Key Distribution Center) vs Asymmetric Key Exchange

Today I was reading notes about cryptography and I came across a problem that exists in Symmetric Key encryption, which is how to share the secret key across the network. 1st Method : Make use of ...
3
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2answers
2k views

What hardware technology (GPU, FPGA) is fastest at generating RSA keys?

I'm interested in generating RSA keys in rapid succession and am looking for the correct hardware to so. I think what I'm looking for is very similar to a brute force attack on RSA keys, but my ...
180
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8answers
82k views

Why not use larger cipher keys?

RSA Security commonly uses keys of sizes 1024-bit, 2048-bit or even 3072-bit. And most Symmetric algorithms only between 112-bit and 256-bit. I do realize that the current keys are secure enough for ...
25
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7answers
9k views

Why don't people hash and salt usernames before storing them

Everyone knows that if they have a system that requires a password to log in, they should be storing a hashed & salted copy of the required password, rather than the password in plaintext. What I ...
5
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3answers
892 views

Impact of Quantum Computers, other than new algorithms

When large scale quantum computers come along, algorithms based off of the new principles will have an impact on how we encrypt data, with Shor's algorithm rendering RSA vulnerable and Grover's ...
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5answers
2k views

Rainbow table concept for Prime numbers

Is there a concept where pre-computed tables can be used for prime number factorization ? Is it possible that a computer can generate millions of prime numbers, store it and then effectively determine ...
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1answer
2k views

ECDH is better than plain RSA? [closed]

RSALabs recommend using at least 4096 bit long RSA keys to encrypt emails but we have some performance difficulty with 4096 RSA. my noob question is what is ECDH (i didn't understood from wikipedia ...
10
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3answers
2k views

Is it preferable to perform encryption using database functions or code?

Several databases I am familiar with provide functions or modules for encryption. Examples include dbms_crypto for oracle databases and built-in functions for MySQL. Most of the commonly used ...
1
vote
4answers
894 views

RSA and encrypted authentication

Symmetric algorithms such as AES provides modes such as GCM which can be used for authenticated encryption. Assuming that I'm using RSA instead of AES, does it still make sense to add authentication ...
1
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1answer
312 views

Secure Encrypted Chat Protocol [duplicate]

Possible Duplicate: Is there a way to negotiate a secret between 2 parties with no prior knowledge? Imagine two clients who want to establish a secure connection over a server. Both clients ...
2
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3answers
209 views

Given a large enough sampling of public keys could one begin to identify a private key?

For example, an ISP or government capable of tracking millions of keys being exchanged. Would that provide a sample large enough to be able to identify the private key on either end?
4
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3answers
694 views

Two step encryption

Consider the following user case: I have some sensitive data (eg: credit card number) I encrypt this data and store it in the database Now I want to send this data to a user X, but I don't want to: ...
2
votes
1answer
269 views

Design of Initialisation Vector

I understand that an IV (initialisation vector) should be both unique and unpredictable, but I have found little guidance as to which is most important. For an AES cipher I have a block size of 128 ...
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13answers
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VP of IT claims he unhashed 100% of all 16k employees' PWs. Is he lying to us?

I work for a company which has ~16,000 employees. Periodically, our VP of IT sends out a newsletter with "tech-tips" and misc IT stuff. The topic of this week's newsletter was "password security". ...
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2answers
101 views

Any good products that could crypt the files stored in laptops? [closed]

Thefts of laptops have become very common at my place, and losses of sensitive information is a a major concern for my businesses. So I wonder if there is any good products out there that could crypt ...