sha256 | 易学教程

Pre-processing SHA256 Python implementation

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问题 I am working my way through the SHA256 implementation on wikipedia but have came up stuck. I have just tried to write the code for the message pre-processing and my length for the final message is 504 bits, not the 512 required. Wikipedia: SHA256 Pre-processing: append the bit '1' to the message append k bits '0', where k is the minimum number >= 0 such that the resulting message length (modulo 512 in bits) is 448. append length of message (without the '1' bit or padding), in bits, as 64-bit

MySQL: UNIQUE text field using additional HASH field

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问题 In my MySQL DB I have a table defined like: CREATE TABLE `mytablex_cs` ( `id` mediumint(8) unsigned NOT NULL AUTO_INCREMENT, `tag` varchar(6) COLLATE utf8_bin NOT NULL DEFAULT '', `value` text COLLATE utf8_bin NOT NULL, PRIMARY KEY (`id`), KEY `kt` (`tag`), KEY `kv` (`value`(200)) ) ENGINE=MyISAM AUTO_INCREMENT=7 DEFAULT CHARSET=utf8 COLLATE=utf8_bin I need to implement a UNIQUE constraint (key) on the value field. I know that is not yet possible to define a unique index on the entire value

Converting hex to base64 in Objective C?

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问题 I had created a SHA256 encoding of the string using the following function, const char *s=[@"123456" cStringUsingEncoding:NSASCIIStringEncoding]; NSData *keyData=[NSData dataWithBytes:s length:strlen(s)]; uint8_t digest[CC_SHA256_DIGEST_LENGTH]={0}; CC_SHA256(keyData.bytes, keyData.length, digest); NSData *out=[NSData dataWithBytes:digest length:CC_SHA256_DIGEST_LENGTH]; NSString *hash=[out description]; hash = [hash stringByReplacingOccurrencesOfString:@" " withString:@""]; hash = [hash

Is it safe to use PBKDF2 with SHA256 to generate 128-bit AES keys?

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问题 I want to use PBKDF2 with some cryptographic hash function to generate 128-bit AES keys. SHA1 is also 128-bit, so I thought of using that with PBKDF2, but it was broken, so I have opted to use SHA256 instead. Is this safe, or will the difference between the hash size and resulting key size cause some sort of disastrous silent truncation that will render the AES keys weak? Should I just have it generate 256-bit keys for AES instead? 回答1: While SHA-1 is "broken", most reasonable systems only

NodeJS implementation for Python's pbkdf2_sha256.verify

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问题 I have to translate this Python code to NodeJS: from passlib.hash import pbkdf2_sha256 pbkdf2_sha256.verify('12345678', '$pbkdf2-sha256$2000$8R7jHOOcs7YWImRM6V1LqQ$CIdNv8YlLlCZfeFJihZs7eQxBsauvVfV05v07Ca2Yzg') >> True The code above is the entire code, i.e. there is no othe parameters/settings (just run pip install passlib before you run it to install the passlib package). I am looking for the correct implementation of validatePassword function in Node that will pass this positive

SHA256 giving 44 length output instead 64 length

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问题 I am using the following code to perform SHA256. public static string GenerateSaltedHash(string plainTextString, string saltString) { byte[] salt = Encoding.UTF8.GetBytes(saltString); byte[] plainText = Encoding.UTF8.GetBytes(plainTextString); HashAlgorithm algorithm = new SHA256Managed(); byte[] plainTextWithSaltBytes = new byte[plainText.Length + salt.Length]; for (int i = 0; i < plainText.Length; i++) { plainTextWithSaltBytes[i] = plainText[i]; } for (int i = 0; i < salt.Length; i++) {

Password Hashing - Why salt 60,000 times

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问题 I'm working for a Fortune 100 company and I'm thrown into being tasked with security moving from SHA1 to SHA-2 . This is not my area of expertise, but as I study cryptography I am questioning the outdated information etc... SHA-2 is obviously needed over SHA-1 but when the security team KNOWS that the hashing of password + salt is using SHA, with GPU being so ridiculously fast at cracking billions of hashes - I do not get why for passwords i'm not being told to use bcrypt or another

Want to Convert a Website password Encryption from SHA1 to SHA256

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问题 just looking for some advise. I have a website with around 2500 users - small but growing. I built it with using SHA1 encryption on the passwords. I've since read the SHA1 is insecure and would like to change to say SHA256 with a Salt. Does anyone have any advice on how to make a transition like this? Would be great if I could decrypt the passwords and just re-hash them but it doesn't appear doing able. thx Adam 回答1: The usual way of going about this is this: Make the hashed-password column

Django pbkdf2_sha256 JS implementation

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问题 I have a database from django and I want to work with it from Node.js. I have a task: authenticate users. Known from database: algorithm pbkdf2_sha256, salt, 10000 iterations and base64-encoded hash. What steps I must to do in JS to encode some password to given base64-hash? UPD: found the solution in here: python (django) hashlib vs Nodejs crypto but Django-generated hash and JS-generated hash not match... Django generate next: pbkdf2_sha256$10000$NmzpPCQiTe2R$U8ipSsOy3Xz7FwWDHdH

Ubuntu系统中docker本地镜像的位置

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Ubuntu 16.04 Dockerversion 1.12.6, build 78d1802 从官方库pull一个镜像：docker pull ubuntu:14.04 一、在image文件夹中寻找 1.找到镜像库的文件首先看repositories.json中的数据 root @ubuntu :/var/lib/docker#cat /var/lib/docker/image/aufs/repositories.json | python -mjson.tool { "Repositories": { "ubuntu": { "ubuntu:14.04":"sha256:4a2820e686c449bc943eab8492df4b4eb7f7e8fabda5258d7bc551fec5790436", "ubuntu@sha256:5faf6cb681da2be979a177b60d8c18497f962e3d82268c49db6c74008d0c294d":"sha256:4a2820e686c449bc943eab8492df4b4eb7f7e8fabda5258d7bc551fec5790436" } } } 看看，是不是正好和docker images的内容一致呢 root @ubuntu :/var/lib/docker#docker images