hmac

I am now trying to encode the string using HMAC-SHA256 using Java. The encoded string required to match another set of encoded string generated by Python using hmac.new(mySecret, myPolicy, hashlib.sha256).hexdigest() . I have tried Mac sha256_HMAC = Mac.getInstance("HmacSHA256"); SecretKeySpec secretKey = new SecretKeySpec(secret.getBytes(), "HmacSHA256"); sha256_HMAC.init(secretKey); byte[] hash = sha256_HMAC.doFinal(policy.getBytes()); byte[] hexB = new Hex().encode(hash); String check = Hex.encodeHexString(hash); String sha256 = DigestUtils.sha256Hex(secret.getBytes()); after I print them

I'm thinking of using AES256 CBC + HMAC SHA-256 as a building block for messages that ensures both confidentiality and authentication. In particular, consider this scenario: Alice is possession a public key belonging to Bob (the key exchange and algorithm is outside the scope of this question). Alice has an identifying key K, also shared with Bob, that she can use to identify herself with. Only Alice and Bob knows the key K. Alice encrypts (nonce || K) using Bob's public key. Bob decrypts the packet and has now has K and nonce. Bob uses SHA-256 with SHA256(K || nonce) to yield a K(e) of 256

My understanding of a message digest is that it's an encrypted hash of some data sent along with the encrypted data so you may verify that the data has not been tampered with. What is the difference then between this and message authentication codes (MAC) and hash MACs (HMAC)? LukeH A message digest algorithm takes a single input -- a message -- and produces a "message digest" (aka hash) which allows you to verify the integrity of the message: Any change to the message will (ideally) result in a different hash being generated. An attacker that can replace the message and digest is fully

T am trying to use HMAC to hash a data string but for some reason my PHP and Python scripts results are not consistent... I can't figure out why. The one that is technically working is the Python script and although I get results from PHP script, the hex returned is incorrect. UPDATE -- one thing i'v noticed is if i am using a single line for the data then the results are identical. The mismatch seems to occur when there is multi-line data. Python demo script here https://repl.it/BBDH/2 Result: f54617eadc7c037b4ed484103bb21426994110a9 import hashlib import hmac import base64 key = b"M0u$t4fa

2.2 散列算法介绍 散列算法介绍 2.2.1 散列算法（函数） 2.2.1.1 概念 2.2.1.2 数字签名（见PKI） 2.2.1 散列算法（函数） 概念 散列函数没有密钥，散列函数就是把可变输入长度串(叫做预映射， Pre-image)转换成固定长度输出串(叫做散列值)的一种函数。 散列函数又可称为压缩函数、杂凑函数、消息摘要、指纹、密码校验和、信息完整性检验(DIC)、操作认证码(Message Authentication Code， MAC)。 哈希消息验证码（HMAC） 用法： 可以利用散列函数进行数据文件的完整性校验。 数字签名（见PKI） 常用的消息摘要算法有： MD5算法 SHA算法 RIPEMD算法 MAC： 消息认证码（带密钥的Hash函数）。密码学中，通信实体双方使用的一种验证机制，保证消息数据完整性的一种工具。 安全性依赖于Hash函数，故也称带密钥的Hash函数。消息认证码是基于密钥和消息摘要【hash】所获得的一个值，可用于数据源发认证和完整性校验。 1. 发送者通过MAC算法计算出消息的MAC值，并和消息一起发给收信者 2. 收信者用同样的MAC算法计算收到的消息的MAC值，并对比两者。 HMAC： Hash-based message authentication code，利用哈希算法，以一个密钥和一个消息为输入，生成一个消息摘要作为输出。

I am following this example http://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-query-string-auth.html and trying to reproduce the 64 character string for the signature which they state as... aeeed9bbccd4d02ee5c0109b86d86835f995330da4c265957d157751f604d404 I have successful matched the hex digeset for the Canonical Request and positive that the StringToSign string is correct. The last piece is calculating the signing_key and signature. This is where I am hitting a road block using the provided ruby function 'getSignatureKey' http://docs.aws.amazon.com/general/latest/gr/signature-v4-examples