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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Is Steganography considered encryption and subject to USA export restrictions?
I have written an application for Apple's iOS which embeds messages in JPEG files using steganography (see http://en.wikipedia.org/wiki/Steganography). For the purposes of this question lets assume ...
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503 views
Online Government Elections System - Is it possible?
I am from Bulgaria and currently some groups here are promoting the idea of referendum among the people, about the possibility for establishing a system for ONLINE GOVERNMENT ELECTIONS. The idea is ...
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5answers
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Asymmetric vs Symmetric Encryption
I am currently taking a principles of information security class. While talking about different encryption methods a large number of my classmates seem to believe that Asymmetric Encryption is better ...
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Looking for example of well-known app using unsalted hashes
Does anyone know of a well-known application that still uses unsalted hashes for password storage? I'm looking for an example for an upcoming lecture on Rainbow Tables, and I think it would add ...
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2answers
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What is the difference between a Hash Function and a Cryptographic Hash Function?
I mean, is it just a matter of "how dificult is it to reverse the function with the current technology"?
Or is there a mathemathical concept or property that makes them diferent?
If it is a matter ...
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How does RSA encryption compare to PGP?
On this answer ck says
RSA and PGP are different.
What you are essentially asking is how
do I run my petrol car on diesel? The
answer is you can't.
I would be interested in a more ...
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5answers
451 views
What is the potential impact of the alleged OpenBSD IPSEC attack?
Recently there is a bit of concern over encryption back doors in IPsec and while the status of this has not been confirmed, I don't know what impact something like this might have.
For instance, does ...
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2answers
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symmetric encryption session keys in SSL/TLS
This question concerns the session send and receive keys used in SSL/TLS protocol. my understanding is that this key uses symmetric encryption (DES, AES, BlowFish, etc.) I'm wondering, if ...
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Encrypting data by parts vs encrypting the whole data
Suppose I have a file with records, and I have two options to encrypt it:
encrypt the file as a whole
encrypt each record separately and store them together.
Which way is generally preferable and ...
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4answers
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What ciphers should I use in my web server after I configure my SSL certificate?
There are many great questions that ask what is the best certificate to use for a website; but once the certificate is purchased, there is also the possibility to choose or edit the Cipher list.
...
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2answers
413 views
Is a large number of RSA-encrypted files a vulnerability?
Would having a large number (10^4) of RSA encrypted files make it easier for an attacker to find my private RSA key?
Update: These files would be available to the attacker, and perhaps the content of ...
11
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1answer
266 views
What are the problems with encrypted but unsigned data?
In another question's answer, D.W. wrote:
Make sure there is authenticity protection for the encrypted data (e.g., encrypt and then sign/MAC): you will need both confidentiality and authenticity ...
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2answers
551 views
How many iterations of Rabin-Miller should be used to generate cryptographic safe primes?
I am generating a 2048-bit safe prime for a Diffie-Hellman-type key, p such that p and (p-1)/2 are both prime.
How few iterations of Rabin-Miller can I use on both p and (p-1)/2 and still be ...
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2answers
540 views
Doubling up or cycling encryption algorithms
I've occasionally read the suggestion to enhance security by either doubling up on encryption algorithms (encrypt a message once with one algorithm, then encrypt the ciphertext again with a different ...
11
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1answer
3k views
Does Windows really still use unsalted MD4 for password storage?
I find it quite difficult to believe that the passwords in Active Directory for Windows 2008 R2 are still stored using the unsalted MD4 (aka "NT Hash") algorithm.
Can it really be true?
I've been ...
11
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2answers
602 views
Evaluating the entropy gathering in a PRNG
I'm reviewing the random number generator (expected to be of cryptographic quality) on an embedded device. My point of view here is the operating system and crypto library implementer. I'm ...
11
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2answers
706 views
Flaw in encryption through pseudorandom number stream (from gpg documentation)
I was reading PGP docs and came upon a part written by Phil Zimmermann (PGP's creator) that piqued my curiosity:
When I was in college in the early 70s, I devised what I believed was a brilliant ...
11
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1answer
670 views
How would I implement “Broadcast Encryption”?
I have a stream that I want to encrypt for broadcast to 10,000 subscribers. I know I should encrypt this data using a symmetric key; and also intend that this symmetric key will be rotated every 30 ...
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7answers
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What are the realistic, and most secure crypto for Symmetric, Asymmetric, Hash, Message Authentication Code ciphers?
I'm interested in updating this two pronged question for 2011:
What cryptology is most appropriate for low-powered devices (such as a cellphone), and yet still effective?
What cryptology is most ...
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4answers
886 views
Question of importance of FIPS in security implementations
I am by far, no security expert but I experience on the subject working in Java (JCA,JCE and JSSE).
Anyway, recently there was a discussion about FIPS compliance.
I looked into this and SUN's ...
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6answers
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Is PBKDF2-based System.Cryptology.RFC2898DeriveBytes() “better” for Unicode Password hashing than traditional methods?
When is it appropriate to use RFC2898DeriveBytes versus a typical hash?
Update
I now understand that a KDF is typically used to create a symmetric key for possible use in encrypting a stream. I ...
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2answers
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What are the differences between MD5, SHA and RSA?
MD5 tools output hexadecimal values. In the same manner, do SHA and RSA together produce a hexadecimal (or any other) output?
What are the differences between the MD5, SHA and RSA algorithms?
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Security of using passwords or even passphrases to encrypt files
Is it ever appropriate to use real-world passwords to encrypt files to be sent via unsecure means.
By real world, I mean a password that is memorable and memorisable by a mere person?
I am implying ...
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6answers
766 views
Shouldn't GPG key fetching use a secure connection?
If I run this for example:
gpg --keyserver hkp://keyserver.ubuntu.com --recv-keys 0xFBB75451
then does the importing occur in a secure way? I mean does it go over only secured connections? (HKP?) ...
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4answers
947 views
Using computer random number generators to produce keys, it is secure?
Does generating an encryption key using the random number generator on one's computer present a security risk? If so how might that risk be mitigated, specifically when generating RSA key pairs in ...
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6answers
870 views
Identity-Based Encryption - how secure is it?
I was always taught never to invent my own crypto algorithm, and never to trust someone who has a proprietary algorithm.
I'm looking at Voltage SecureMail, which uses IBE (identity-based encryption) ...
10
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4answers
652 views
Why isn't OCSP required by default in browsers?
According to the following screenshot, taken from firefox-3.6.17-1.fc14.i686, Firefox has an option to fail closed when unable to connect to OCSP servers.
Can someone please explain why this isn't ...
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6answers
305 views
Should we configure all devices to never request SSL 2.0, and reject it if offered?
In an effort to reduce man in the middle attacks, when will it be (or was it) an industry accepted practice to reject SSL 2.0 connections on the client and server side?
Is configuring this on a proxy ...
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3answers
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Computationally simple, lightweight replacement for SSL/TLS
Target hardware is a rather low-powered MCU (ARM Cortex-M3 @72MHz, with just about 64KB SRAM and 256KB flash), so walking the thin line here. My board does have ethernet, and I will eventually get ...
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5answers
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Do mobile OS's provide crypto-quality randomness?
Which mobile OS's provide a primitive to generate crypto-quality randomness that applications can use?
On desktop systems, these features are pervasive. Unix provides /dev/urandom. Windows provides ...
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2answers
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Why are GPUs so good at cracking passwords?
What is it about GPUs that lets them crack passwords so quickly?
It seems like the driving force behind adopting good key-derivation functions for passwords (bcrpyt, PBKDF2, scrypt) instead of ...
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OS with encrypted RAM?
Are there any applications, JIT frameworks or operating systems that focus on encrypted virtual memory, or perhaps virtual machines that do something similar? I know there are processors (albeit old, ...
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520 views
Cryptographic Security of Dynamically Generated, Non-Random Salts
So when it comes to security, when I have an idea that seems good, but no one else seems to be doing, I try to assume that I'm overlooking something obvious or otherwise significant. This is one such ...
10
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881 views
MS-SQL Password Storage
What would be your recommendation for replacement of an MD5 hash approach to password storage within an MS-SQL database be?
10
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2answers
284 views
How much security is compromised if we accept other characters as login (other than the original password)?
I've just realised that facebook accepts 3 forms of a password:
Source:
Facebook actually accepts three forms of your password:
Your original password.
Your original password with the ...
10
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1answer
566 views
Native rsync protocol security
Is the native rsync protocol (port 873) secure? Does it encrypt data or credentials?
I'm planning on using rsync to store encrypted files in the cloud, I'm wondering whatever the password is ...
10
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1answer
893 views
TrueCrypt, Master password possible?
I recently was talking with somebody, and they said something along the lines of TrueCrypt having a "master key" password that certain authorities have.
Now, from what I know about how TrueCrypt ...
10
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1answer
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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 ...
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1answer
854 views
Timing attacks on password hashes
Timing attacks can have a devastating impact in scenarios where the secret is involved, often in cases where byte-wise array comparison is used.
Now there are those that advertise using constant ...
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2answers
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GnuPG/OpenPGP Key Practices
I'm looking for input on GnuPG (gpg) best practices. It's been discussed some on the gnupg-users mailing list, but I wanted to get as diverse a view as possible, so I thought to bring the topic to ...
10
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2answers
188 views
What are the practical uses of large asymmetric keys?
The Windows CNG supports keys of varying sizes, e.g. RSA up to 16384 bits: http://msdn.microsoft.com/en-us/library/windows/desktop/bb204778(v=vs.85).aspx.
My understanding is that in crypto today we ...
10
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1answer
297 views
What did Blackberry do wrong?
The NIST defines a vulnerability in RIM Blackberry encryption discovered last October.
Apparently, Blackberry's flavour of PBKDF2 was weak. They say:
The offline backup mechanism in Research In ...
10
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3answers
574 views
Key management in cloud datacenters
In terms of infrastructure, how do Cloud providers (organizations providing SaaS, PaaS, or IaaS via the cloud) manage keys and cryptography?
From my understanding, "private" datacenters tend to ...
9
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2answers
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Cracking a linear congruential generator
I was recently listening to the security now podcast, and they mentioned in passing that the linear congrunential generator (LCG) is trivial to crack. I use the LCG in a first year stats computing ...
9
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4answers
4k views
Is it possible to securely store passwords using reversible encryption?
Everyone says that you need to use a non-reversible hash when you store passwords so that even if your database is leaked, the passwords themselves are still safe. I'm wondering if there is anyway to ...
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5answers
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Use RSA keypair for PGP encryption and decryption
Is there a way that I can use a RSA keypair with PGP?
What I mean is that I have 2048 length keypair and i want to use that to encrypt and decrypt data. But all I have found is that the PGP uses some ...
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What are the most common password salting methods?
I learned that the Sun guys used the login name as salt for password hashing. Is this a common approach?
What are the most common salt values?
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Is there any advantage of bcrypt over multiple iterations of SHA-x/MD5?
I know that a good password hashing algorithm should be slow. MD5, SHA256, etc. are fast. So I've been adding multiple iterations of SHA-256 hashing to my web apps (around 50000). Getting the hash of ...
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3answers
797 views
How to exchange RSA public keys safely between two parties?
How to exchange RSA public keys safely between two parties via internet?
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2answers
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In the recent DKIM vulnerability, how did someone determine key length by looking at headers?
Having read this recent article : Wired-DKIM vulnerability, I have a couple of questions.
How can one determine the key length that is being used simply by looking at the headers ?
And I'm assuming ...
