Take a commonly used binary hash function - for example, SHA-256. As the name implies, it outputs a 256 bit value. Let A be the set of all possible 256 bit binary values. A is extremely large, but finite. Let B be the set of all possible binary values. B is infinite. Let C be the set of values obtained by running SHA-256 on every memb...
What is the difference in this class? as posed to just using Encoding.ASCII.GetBytes(string object); I have had relative success with either approach, the former is a more long winded approach where as the latter is simple and to the point. Both seem to allow you to do the same thing eventually but I am struggling to the see the point i...
Could put a little example about the use of crypto/rand [1]? The function Read has as parameter an array of bytes. Why? If it access to /dev/urandom to get the random data. func Read(b []byte) (n int, err os.Error) [1] http://golang.org/pkg/crypto/rand/ ...
Hello, In an app we are calculating a SHA1Hmac in java using the following: SecretKey key = new SecretKeySpec(secret, "HmacSHA1"); Mac m = Mac.getInstance("HmacSHA1"); m.init(key); byte[] hmac = m.doFinal(data); And later, the hmac is verified in C# - on a SmartCard - using: HMACSHA1 hmacSha = new HMACSHA1(secret); hmacSha.Initi...
I create a triple DES key from the a byte array ("skBytes") but when calling getEncoded on the triple DES key ("sk") and comparing it to the byte array, they differ! They are almost the same if you look at the console output, though. How would I create a triple DES key that is exactly as "skBytes"? byte[] skBytes = {(byte) 0x41, (by...
Hi, Is C# 'RSACryptoServiceProvider' cryptographic algorithm is a part of Microsoft- CryptoAPI? Any advantage we have for normal asymmetric encryption by using CryptoAPI over 'RSACryptoServiceProvider' in .Net? I cannot understand the difference between them?And which one is best and safty? Could you please help? Thanks Karthik ...
Hi there, I'm in the process of designing a web application that will require the storage of GPG keys in an encrypted format in a database. I'm planning on storing the user's password in a bCrypt hash in the database. What I would like to be able to do is to use that bCrypt to authenticate the user then use the combination of the stored...
I am writing a C# application which allows users to store emails in a MS SQL Server database. Many times, multiple users will be copied on an email from a customer. If they all try to add the same email to the database, I want to make sure that the email is only added once. MD5 springs to mind as a way to do this. I don't need to worry ...
Hello, I'm looking for examples + information on how to extract certificate information from the windows certificate store and perform operations like verifying signatures using the retrieved certificates. The API documentation for C# in this regard is quite poor, with many of the entries in msdn marked with "This language is not support...
Is there a good Perl book on cryptology? ...
Can somebody give me a link to PKCS#11 test suite? This may be a simple utility or part of big project no matter. I now only this one: Netscape PKCS #11 Test Suites ...
Is calculating an MD5 hash less CPU intensive than SHA-1 or SHA-2 on "standard" laptop x86 hardware? I'm interested in general information, not specific to a certain chip. UPDATE: In my case, I'm interested in calculating the hash of a file. If file-size matters, let's assume its 300K. ...
I would expect that if I have a X509 cert as an object in memory, saved it as a pem file, then loaded it back in, I would end up with the same cert I started with. This seems not to be the case however. Let's call the original cert A, and the cert loaded from the pem file B. A.as_text() is identical to B.as_text(), but A.as_pem() differs...
Does anyone know of a pure DSA module in Python for signing messages? ...
Hi ! In Crypto communities it is common to measure algorithm performance in cycles/byte. My question is, which parameters in the CPU architecture are affecting this number? Except the clockspeed ofcourse :) ...
In the process of building what I'd like to hope is a properly-architected authentication mechanism, I've come across a lot of materials that specify that: user passwords must be salted the salt used should be sufficiently random and generated per-user ...therefore, the salt must be stored with the user record in order to support verif...
I have a quick little app that steps through the possible symmetric encryption methods. I get them with the following line: private static List<Type> GetAlgorithmTypes { get { return Assembly.GetAssembly(typeof(SymmetricAlgorithm)).GetTypes().Where( type => type.IsSubclassOf(typeof(SymmetricAlgorithm))).ToList(); } } ...
In the Wikipedia Article on Block Cipher Modes they have a neat little diagram of an unencrypted image, the same image encrypted using ECB mode and another version of the same image encrypted using another method. At university I have developed my own implementation of DES (you can find it here) and we must demo our implementation ...
Hello, I am trying to make a program that Encrypts data using AES, then encrypts the AES key with RSA, and then decrypt. However, once i encrypt the AES key it comes out to 128 bytes. RSA will only allow me to decrypt 117 bytes or less, so when i go to decrypt the AES key it throws an error. Relavent code: KeyPairGenerator kpg = K...
how do you store an rsa encrypted data block? the output might be significantly greater than the original input data block size, and i dont think people waste memory by padding bucket loads of 0s in front of each data block. besides, how would they be removed? or is each block stored on new lines within the file? if that is the case, how...