Ok, so the problem is that you are converting the encrypted bytes to a hex string (using the asHex method) but are not converting the hex string back to a byte array correctly for decryption. You can’t use getBytes. You can use the following method to convert a hex string to a byte array: public … Read more
For dot net framework 4.7.0 or higher is not taking the sha1 so configure the below in application start. it’s worked fine for me. AppContext.SetSwitch(“Switch.System.Security.Cryptography.Xml.UseInsecureHashAlgorithms”, true); AppContext.SetSwitch(“Switch.System.Security.Cryptography.Pkcs.UseInsecureHashAlgorithms”, true);
The java AES library has a flaw in it that allows, under the right circumstances, a listener to decrypt the packets sent. See Padding Oracle Exploit Tool vs Apache MyFaces. That being said check out this SO question Java 256bit AES Encryption. Bouncy Castle AES EXAMPLE stolen from: http://www.java2s.com/Code/Java/Security/EncryptionanddecryptionwithAESECBPKCS7Padding.htm import javax.crypto.Cipher; import javax.crypto.spec.SecretKeySpec; public class … Read more
Intel has upcoming instructions for accelerating the calculation of SHA1 /256 hashes. You can read more about them, how to detect if your CPU support them and how to use them here. (But not SHA-512, you’ll still need to manually vectorize that with regular SIMD instructions. AVX512 should help for SHA-512 (and for SHA-1 / … Read more
MD5, like other hash functions, does not require two passes. To start: HashAlgorithm hasher = ..; hasher.Initialize(); As each block of data arrives: byte[] buffer = ..; int bytesReceived = ..; hasher.TransformBlock(buffer, 0, bytesReceived, null, 0); To finish and retrieve the hash: hasher.TransformFinalBlock(new byte[0], 0, 0); byte[] hash = hasher.Hash; This pattern works for any … Read more
Since everyone until now has simply defined what a hash function was, I will bite. A one-way function is not just a hash function — a function that loses information — but a function f for which, given an image y (“SE” or 294 in existing answers), it is difficult to find a pre-image x … Read more
TL;DR: Use new SecureRandom() when you’re not sure and let the system figure it out. Possibly use SecureRandom.getInstanceStrong() for long term key generation. Do not expect a random number generator to generate a specific output sequence within a runtime application, not even if you seed it yourself. With random number generators it is always hard … Read more
When you use a code like this: using (var rsa = new RSACryptoServiceProvider(1024)) { // Do something with the key… // Encrypt, export, etc. } .NET (actually Windows) stores your key in a persistent key container forever. The container is randomly generated by .NET This means: Any random RSA/DSA key you have EVER generated for … Read more
Edit: You likely are looking for a quick and simple way to do HMAC-SHA256 and not get into the finer details. The original question asks of those finer details which are explained further below. I want to perform a HMAC-SHA256 on a byte[] message input using System.Security.Cryptography; … private static byte[] HashHMAC(byte[] key, byte[] message) … Read more
A cryptographically secure number random generator, as you might use for generating encryption keys, works by gathering entropy – that is, unpredictable input – from a source which other people can’t observe. For instance, /dev/random(4) on Linux collects information from the variation in timing of hardware interrupts from sources such as hard disks returning data, … Read more