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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What kind of encryption is a one-time pad?

Is it a substitution cipher or a stream cipher or both?
13
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3answers
7k views

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.
6
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3answers
238 views

Renew digital certificate

If I have deployed a digital certificate on a webserver and if it needs to be renewed then what steps do I need to follow? Will I need to generate a new longer public key private key pair? Why do ...
6
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3answers
535 views

Personal digital certificate how to verify

A server certificate would have its domain name at its subject field. A personal certificate would have your name as the subject field. How can you be sure that there are no two certificates with the ...
6
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3answers
1k views

Certificate chain

For my computer to verify the identity of a certain certificate should it have all the certificates up to the root certificate?
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2answers
4k views

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 ...
0
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3answers
2k views

3 way authentication

Can someone please tell me what does 3 way authentication mean? I cannot understand this concept? :( Now if there are two people A and B 1.) A challenges B with a question 2.) B gives the answer and ...
3
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1answer
118 views

Protect file in a web site

How would you protect a password file in a web site? Is hashing the individual passwords not enough? What other steps do I need to follow?
9
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2answers
4k views

Encryption decryption time

Does the encryption / decryption time of rsa algorithm vary significantly with a change in key length? For example, is there a noticeable difference in encryption/decryption time between 512 bit and ...
4
votes
1answer
184 views

When does one need to be concerned with leaking timing information in .NET?

According to this post, Dominick Baier was comparing two HMACSHA256 signatures and was leaking timing information upon an unsuccessful comparison. When working with .NET crypto classes, when should ...
4
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2answers
3k views

What is an intermediate certificate authority?

What is meant by an "intermediate certificate authority?"
7
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1answer
2k views

Is SSL key generation client-side, server-side, or both?

Who generates the session keys for a SSL symmetric encryption? Is it the client for both client and server where client generates part of it while the server generates the other part?
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votes
4answers
8k views

Why should one not use the same asymmetric key for encryption as they do for signing?

In an answer to a question about RSA and PGP, PulpSpy noted this: It is possible to generate an RSA key pair using GPG (for both encryption and signing -- you should not use the same key for ...
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3answers
2k 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 ...
2
votes
2answers
148 views

What are the advantages of sequential signing

What the advantage of sequentialy signing a document? That means signing a document by two people in a sequential manner?
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4answers
12k views

How to achieve non-repudiation?

If I have a message that I need to send to another person, how do I achieve non repudiation ? Is digitally signing the message sufficient ?
8
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3answers
5k views

How can I enumerate all the saved RSA keys in the Microsoft CSP?

I have an application that is creating several keys and storing them in various stores (in this case the Machine store). How can I enumerate all the keys on a given Windows system? ...
4
votes
1answer
665 views

Why does Bouncy Castle have a separate download for the IDEA algorithm?

I'm looking at downloading the C# binary for Bouncy Castle and see two downloads with source code. One has the IDEA algorithm, the others presumably not. http://www.bouncycastle.org/csharp/ Why ...
13
votes
7answers
6k views

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 ...
16
votes
2answers
5k views

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 ...
3
votes
1answer
3k views

How do I use C# to encrypt/decrypt data where the private key is on a smartcard, hardware security module, TPM chip etc

Is anyone aware of a C# code sample to interact with smartcard, hardware security module, TPM chips (etc), that will allow me to encrypt and decrypt data? My goal is to allow my application to ...
26
votes
8answers
2k views

If someone breaks encryption, how do they know they're successful?

Let's say I have a file containing a random bunch of bits and then I encrypt it using some modern algorithm (Blowfish, AES, or whatever). If someone captures the file and mounts a brute force attack ...
6
votes
2answers
481 views

How can I authenticate a client connection in a secure way?

Let's say I have a server listening on port 1234. I have some client software that needs to be able to connect to this port. But I want to prevent malicious users from bypassing the client software ...
48
votes
5answers
45k views

What is the difference between SSL vs SSH? Which is more secure?

What is the difference between SSH and SSL? Which one is more secure, if you can compare them together? Which has more potential vulnerabilities?
12
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1answer
327 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 ...
8
votes
2answers
2k views

3DES vs DES for VPN connections

I'm trying to get Android 2.1 phones to connect to our corporate VPN, but it would appear they only support DES rather than 3DES for encryption. Is it safe to use DES, am I going to get hacked if I ...
8
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3answers
2k views

What common products use Public-key cryptography?

I want know what common use products are there that use public key/private key cryptography?
21
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5answers
3k views

PCI Encryption Key Management

(Full disclosure: I'm already an active participant here and at StackOverflow, but for reasons that should hopefully be obvious, I'm choosing to ask this particular question anonymously). I currently ...
7
votes
4answers
1k 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 ...
7
votes
4answers
602 views

What good, standard digital signature verification clients are widely or easily deployed?

I'm looking for a good way to publish data along with a digital signature (and ideally a timestamp) which is as easy as possible to verify. For example, imagine an election administrator who wants to ...
4
votes
6answers
779 views

What are the weaknesses of this password-generation-method? How can it be improved?

I recently came up with the problem, that I have much more accounts, than I'm able to remember passwords. I don't want to use a password-safe, because I cannot access it on another computer, I lose ...
6
votes
3answers
822 views

What are the pros and cons of outsourcing an organization's PKI?

I am looking for the pros and cons of outsourcing an organization's Public Key Infrastructure (PKI). I understand that the answer to whether or not to actually outsource is going to depend on the ...
8
votes
1answer
721 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 ...
22
votes
5answers
8k views

Where to get an SSL certificate for personal website?

I would like to use https to login to my personal webpage (which is on shared hosting). So I went over to google and started searching for sollutions. Eventualy I found out that I need an SSL ...
13
votes
5answers
554 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 ...
15
votes
2answers
2k views

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 ...
9
votes
5answers
678 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 ...
14
votes
3answers
3k views

Forced into using a static IV (AES)

We've had to extend our website to communicate user credentials to a suppliers website (in the query string) using AES with a 256-bit key, however they are using a static IV when decrypting the ...
12
votes
4answers
1k 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?
33
votes
5answers
5k views

Are GUIDs safe for one-time tokens?

I see a lot of sites use GUIDs for password resets, unsubscribe requests and other forms of unique identification. Presumably they are appealing because they are easy to generate, unique, ...
16
votes
2answers
2k views

How secure is Keychain on OS X?

Keychain is a built-in app on OS X that stores all of the user credentials, and allows for one to keep encrypted notes in an easily accessible way. Does anyone know how secure Keychain is? I know ...
10
votes
6answers
382 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 ...
10
votes
2answers
5k 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 ...
0
votes
1answer
593 views

How can I decrypt ADFS-based SAML/p or WS-Trust claims?

I'd like to audit the claims that are sent to a client from a SAML/p or WS-Trust authentication. What private keys do I need and how would I decrypt this information? If it makes any difference, I'm ...
6
votes
2answers
834 views

How effective is the Mac Open Firmware password protection?

I have used Mac's Open Firmware password protection before and I've always wondered how effective it actually is at protecting my stuff. [assuming a good password] Would does the firmware password ...
15
votes
5answers
2k views

The aescrypt implementation hashes a password 8192 times to generate the key. Is this necessary?

I'm considering encrypting some small files (hundreds of kb apiece) using the aescrypt reference implementation. Looking at the source, it seems that the encryption key is derived from the IV and the ...
59
votes
6answers
26k views

How should I distribute my public key?

I've just started to use GPG and created a public key. It is kind of pointless if no-one knows about it. How should I distribute it? Should I post it on my profile on Facebook and LinkedIn? How about ...
61
votes
2answers
10k views

What are rainbow tables and how are they used?

Where can I find one? Is there a pot of gold at the end? How do I protect against them? From the Area51 proposal This question was IT Security Question of the Week. Read the Sep 09, 2011 blog ...
27
votes
5answers
34k views

Advantages and disadvantages of Stream versus Block Ciphers

Encryption algorithms such as Blowfish,AES,RC4,DES and Seal are implemented in one of two categories of ciphers. What are the advantages/disadvantages to the type of ciphers?
17
votes
4answers
1k views

IPsec (Internet Protocol Security) facts

Internet Protocol Security (IPsec) is a successor of the ISO standard Network Layer Security Protocol (NLSP). What are the advantages, disadvantages, other interesting facts regarding the protocol?