cryptography

问题 I'm sorry to ask your skills about a question asked so many times. I have an issue about RSA crypthography. I've already checked the other topics about this issue but i didn't find any helpful answer. I hope you'll be able to help me. I want to read a file, crypt its contain and then decrypt it and put these decrypted bytes in a new file. I actually can : - get the bytes of a file - crypt it I have the exception : javax.crypto.BadPaddingException: Data must start with zero. Here is my code :

问题 Can we have multiple public keys associated with a single private key for RSA public-key encryption? 回答1: In practice and with respect to security, no, mathematically, yes. If you have a private key (N, D), there is algebraically an infinite number of solutions to the equation 1 = E*D (mod Phi(N)). However, if you make two such solutions (E, N) and (E', N) that both satisfy the equation public, you will have compromised the secrecy of the private key. However given one of the usual asymmetric

问题 Can we have multiple public keys associated with a single private key for RSA public-key encryption? 回答1: In practice and with respect to security, no, mathematically, yes. If you have a private key (N, D), there is algebraically an infinite number of solutions to the equation 1 = E*D (mod Phi(N)). However, if you make two such solutions (E, N) and (E', N) that both satisfy the equation public, you will have compromised the secrecy of the private key. However given one of the usual asymmetric

问题 I sent 80 50 00 00 08 00 00 00 00 00 00 00 00 [ INITILIZE UPDATE Command] via opensc-tool to my java card and received 00 00 11 60 01 00 8A 79 0A F9 FF 02 00 11 79 11 36 5D 71 00 A5 A5 EC 63 BB DC 05 CC [ Init Response ] as its response from the card. As you see: In the command,I send 00 00 00 00 00 00 00 00 as Host Challenge , And in the response : 00 00 11 60 01 00 8A 79 0A F9 = Key diversification data FF 02 = Key information 00 11 79 11 36 5D 71 00 = Card challenge A5 A5 EC 63 BB DC 05 CC

问题 Below is my encryption logic. Although my IV is 16bytes long, I still get an error with invalid IV length. Would appreciate any help @Override public String encrypt(String dataToEncrypt, String IV) throws Exception{ if(encryptionKey.length() < 10){ encryptionKey = generateEncryptionKey().toString(); } System.out.println("number of IV bytes is "+IV.length()+" "+IV); Cipher cipher = Cipher.getInstance(encrpytionAlgo); SecretKey key = new SecretKeySpec(encryptionKey.getBytes(Charset.forName("UTF

问题 I'm using a very standard way of Java AES encryption / decryption. byte[] key = hexStringToByteArray("C0C1C2C3C4C5C6C7C8C9CACBCCCDCECF"); byte[] message = hexStringToByteArray("01A0A1A2A3A4A5A6A703020100060001"); SecretKeySpec secretKeySpec = new SecretKeySpec(key, "AES"); // Instantiate the cipher Cipher cipher = Cipher.getInstance("AES"); cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec); byte[] encrypted = cipher.doFinal(message); cipher.init(Cipher.DECRYPT_MODE, secretKeySpec); byte[]

问题 I need to encode/encrypt database ids and append them to my URLs. Security is not an issue I am trying to deal with, but I am looking for something with moderate security. The main goal is to have short ids that are unique and URL-safe. The following snippet seems like it will do what I need (from http://programanddesign.com/php/base62-encode/) function encode($val, $base=62, $chars='0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ') { // can't handle numbers larger than 2^31-1

问题 I can successfully do manual reference validation (canonicalize every referenced element --> SHA1 --> Base64 --> check if it's the same of DigestValue content) but I fail with the verification of the SignatureValue. Here's the SignedInfo to canonicalize and hash: <ds:SignedInfo xmlns:ds="http://www.w3.org/2000/09/xmldsig#"> <ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"></ds:CanonicalizationMethod> <ds:SignatureMethod Algorithm="http://www.w3.org/2000/09

问题 Looking at Go standard library, there's a ConstantTimeByteEq function that looks like this: func ConstantTimeByteEq(x, y uint8) int { z := ^(x ^ y) z &= z >> 4 z &= z >> 2 z &= z >> 1 return int(z) } Now, I understand the need for constant time string (array, etc.) comparison, as a regular algorithm could short-circuit after the first unequal element. But in this case, isn't a regular comparison of two fixed-sized integers a constant time operation at the CPU level already? 回答1: Not

问题 So I'm trying to figure out how to do a hmacshad256 hash on ios as that's the hash I did for the wcf service api I made. I've been trying to look for some info about it but would usually just end up getting a SHA-256 hash. This is the only reference I have: Need to generate HMAC SHA256 hash in Objective C as in Java And I'm not sure if that's the only way to do it (importing a java hmac class) Any help is appreciated. Thanks! 回答1: NSString * parameters = @"string to hash" NSString *salt = @