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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Multiple CAs signing a single Cert/CSR?
Just saw this suggested on Slashdot
So I've seen quite a few people wanting a switch to self-signed certs (who IMO mostly don't understand what making that secure actually involves), and an idea ...
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1answer
113 views
Is there an organization that reviews/approves crypto implementations?
As I understand it, NIST approves crypto algorithms but doesn't cover specific implementations. I think I've read about IEEE approving hardware implementations of, e.g. AES, but I can't think of any ...
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543 views
When brute-forcing DES, does knowing something about the plaintext help?
Data Encryption Standard (Wikipedia)
I know that with brute force there are 2^56 possible keys to check (56 bits, each either a 1 or 0). But let's say I know the message itself is only made up of ...
9
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2answers
548 views
Does my PGP key really need to match the e-mail address for which I'll be using it?
In considering whether or not I want to join the big web o' trust and put my keys on a key server, I got to thinking about how it would affect my e-mail address' exposure. I generally try to keep my ...
9
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3answers
981 views
Question about dictionary attacks on GnuPG symmetric encryption
They say algorithms like AES can't practically be broken given a long enough key length (> 128 bits). If I use GnuPG to encrypt a file using AES:
gpg -c --cipher-algo AES secretfile
it asks me for a ...
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1answer
1k views
TLS replay attack - requirements of the serverHello nonce
As you all know, the SSL/TLS protocol requires both client and server to exchange (in clear text) a random number or nonce. This is presumably used to prevent replay attacks.
It is not clear to me ...
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593 views
Is TDEA (TripleDES) invulnerable to the weak keys of DES?
The key space of DES includes some keys that are weak, which results in a ciphertext that is extra vulnerable to cryptanalysis.
Is TDEA (also known as TripleDES) invulnerable to those weak keys? Or, ...
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1answer
332 views
What role does cryptography play in anti-piracy?
As a follow-up to Cipher for Product Registration, are there secure yet usable cryptographic standards/protocols for protecting software and data used by software? I'm interested in hardware and ...
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2answers
575 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 ...
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1answer
210 views
Optimal variable sizes in the Secure Remote Password protocol
I am implementing the Secure Remote Password protocol:
U = <username> -->
<-- s = <salt from passwd file>
a = random()
A = g^a ...
8
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6answers
549 views
Does prepending a salt to the password instead of inserting it in the middle decrease security?
I read somewhere that adding a salt at the beginning of a password before hashing it is a bad idea. Instead, the article claimed it is much more secure to insert it somewhere in the middle of the ...
8
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4answers
316 views
Atypical DRM situation: distribute pictures to select partners, then prevent them from reusing them
We want to distribute digital content (think pictures) to a select number of partners (around 1000, worldwide) to use as visual reference. We would like however to prevent them from copying or in any ...
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5answers
336 views
What can one do when encryption methods fail?
I'm in search of an expert to answer my curiosity. Suppose that methods like AES/DES, SSH, PGP, RSA, etc. can be cracked or fail somehow. In other words, suppose that it's possible to determine one ...
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1k views
What common products use Public-key cryptography?
I want know what common use products are there that use public key/private key cryptography?
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Compute the AES-encryption key given the plaintext and its ciphertext?
I'm tasked with creating database tables in Oracle which contain encrypted
strings (i.e., the columns are RAW). The strings are encrypted by the application
(using AES, 128-bit key) and stored in ...
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3answers
1k views
time to crack file-encryption password - more than just iteration
I have often seen that takes x amount of time to crack a certain length password. But this just seems to be the amount of time it takes to iterate through all the possibilities. What about the time it ...
8
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5answers
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What is the benefit with using encrypted RAM Memory?
I sometimes hear that encryption is used for the RAM Memory, but I don't really understand why this is needed.
Why is RAM Memory needed to be encrypted? and is this done by the hardware, the ...
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2answers
596 views
Are there really functioning quantum computers?
I saw this video on youtube on quantum computing. It says that a company called dwavesys has already made commercially available quantum computer. I checked on the website and it exists. I thought ...
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2k views
How can I decrypt data with Java, without hard-coding the key?
I hope this is not a chicken-egg problem or reinventing the wheel but here goes.
I have a Java application that needs to access a password protected file (actually during the application startup).
The ...
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3answers
748 views
How does an SSL server prove its identity?
This document says that a challenge response authentication proves the servers identity. But is a man in the middle attack still possible if the client does not verify domain name ? Please help me ...
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2answers
2k views
Can the numbers on RSA SecurID tokens be predicted?
My workplace uses these SecurID tokens which provide you with a temporary password, the code will expire after a short time. I have always been fascinated by the things, because it seems as though ...
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3answers
4k views
SSL handshake failure modes
In SSL if the handshake is not succesful, does it always end with a handshake alert?
Or are there other ways to finish the SSL connection (acceptable by standard).
I am asking this, because in an ...
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3answers
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How can I export my private key from a Java Keytool keystore?
I would like to export my private key from a Java Keytool keystore, so I can use it with openssl. How can I do that?
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moving from MD5 to SHA-512
This question is more of a security policy than a technical security question.
Many years ago I developed an asp.net site, implemented Forms Authentication, and stored the user passwords as MD5 ...
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3answers
437 views
Most widespread use of PGP after 20 years
Phil Zimmerman released PGP (Pretty Good Privacy) on June 5, 1991. As we examine the legacy of that far-sighted and brave act 20 years later, what are the most widespread and helpful uses of PGP ...
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5answers
214 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 ...
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3answers
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What are the risks of self signing a certificate for SSL
Let's say I sign a SSL certificate for myself, and I'm not using a certified CA. What are the risks and/or threats of doing it?
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Why can an encrypted private key be brute forced?
When using SSH keys to authenticate to a server for remote access, why is it possible to devise the true key and therefore the passphrase from an encrypted private key, without checking each guess of ...
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3answers
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Whats the difference between MAC vs hash
What is the difference between the two algorithms?
One difference that I know of, is that MAC is keyed and hash is not.
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2answers
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SSL Certificate revocation check
In the SSL protocol I don't see where the certificate is checked for revocation status.
https://developer.mozilla.org/en/Introduction_to_SSL
Is the Certificate Revocation and Status Checking not ...
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3answers
801 views
How can I mitigate the threat that DPAPick poses to my DPAPI protected data?
The Windows Data Protection API (DPAPI) is the suggested method for storing secrets on Windows systems (such as database passwords required by ASP.Net applications).
DPAPick was presented at BlackHat ...
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2answers
2k views
What are the differences between the versions of TLS?
Please correct me if I'm wrong, but my understanding is that SSLv3 and TLSv1 is just a rename of the earlier protocol... but TLSv1 adds the ability to have secured and unsecured traffic on the same ...
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2answers
807 views
Which cipher suites with AES cipher provide forward secrecy?
Does standard AES with RSA (reported by Opera as TLS v1.0 256 bit AES (1024 bit RSA/SHA)) provide perfect forward secrecy?
Which SSL3.0 and TLS1.0 ciphers do provide forward secrecy?
Which ciphers ...
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329 views
Which authentication at the end of the Secure Remote Password protocol?
For the the client and server to prove to each other that they have the same premaster shared key, the original author suggests this:
M = H(A | B | K) -->
<-- H(A | M | K)
...
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1answer
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Howto seed the PRNG in OpenSSL properly?
I am creating an application which runs on a mobile node with Ubuntu, which does not generate enough entropy bytes to the /dev/random, and does not always stay connected on the Internet to use typical ...
8
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3answers
483 views
Does the SSL encryption strength of a website really matter?
When looking to get an SSL certificate one is presented with a lot of options. For example lets take Network Solutions since they have a nice comparison chart.
Immediately there seems to be 4 major ...
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1answer
381 views
Is a 2047-bit prime weaker than a 2048-bit prime?
I have a safe prime generator I'd like to speed up. I can benefit from a significant performance gain if the high order bit in the returned prime can be either 1 or 0. The returned prime would be ...
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Suitable cipher for SMS encryption
I would like to create application for encrypting SMS messages. After long enough discussions I decided to use symmetric encryption, since handling public/private keys issue is too difficult for most ...
8
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1answer
283 views
Any risk in using the same salt for several hashes on a user?
Right now I'm storing a salt and password_hash on the users table (pretty standard stuff).
The need arose to get a secure hash of another field for a user. Is there any risk in reusing the same salt ...
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3answers
340 views
Are there any smartcard/hardware-tokens for certificate-based authentication which are easily destroyed?
It's all very well to use multi-factor authentication, but supposing you want to 'destroy a factor' so that in an situation where you are likely to be coerced to provide your passphrase, you can ...
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1answer
508 views
What were the specific security flaws with OAuth 1.0? How are they being addressed in 2.0?
I read an article documenting Twitter abruptly pulling its OAuth support back in April 2009. The article said it wouldn't specify the hole for security reasons, but mentioned "social engineering" is ...
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1answer
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Wheres the salt on the openssl aes encryption?
Im 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 them
...
8
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3answers
141 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 ...
7
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2answers
675 views
How difficult is it to modify an ISO image and still have the old md5 check sum?
If I want to download the ubuntu11.04.iso then:
UBUNTUMIRRORSRV -> ISP -> ISP -> etc. -> MYPC
I just want to ask that how difficult is to spoof the original MD5 sum (e.g.: the md5sum would be ...
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8answers
567 views
Is the following authentication scheme secure?
I was trying to design an authentication system that would make it much harder to guess a password via brute force, and reduce the risk to a user if the hashed password was stolen through a snooping ...
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4answers
736 views
Copyright issues with encryption algorithms
I'm developing application for Android/Java. Application is a kind of password manager, so I'm storing encrypted passwords under the hood of master password. There are number of encryption algorithms ...
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3answers
403 views
It is possible that brute force attempts are successful before the worst case, correct?
When I read about a password being secure and stating that it would take X amount of week, years, etc. isn't that referring to the worst case?
What happens if the brute force method is successul in ...
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Certificate authorities for a PKI
Some people think the certificate authorities for a PKI should be the government, but others think certificate authorities should be private entities, such as banks, corporations, or schools. What are ...
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957 views
Is using HMAC to transmit a password OK?
I'm writing a small webapp and I don't want to transmit login passwords as cleartext. As I don't have SSL available I've written a one-time challenge system which sends a random string with the login ...
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4answers
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What Partial Homomorphic Encryption implementations exist and how do I leverage them?
It appears that only Partial Homomorphic Encryption(P.H.E.) is practical for modern day (2011) use. However I'm having difficulty locating libraries (FOSS or otherwise) that enable me to leverage ...
