• ## SQL Server encryption and decryption

Time：2021-3-4

1、 Passphase encryption 1.1 summary 1) For emergency data encryption without certificate and key, the data can be encrypted and decrypted directly based on the password provided by the user. 2) A pass phrase is a password that allows spaces. This passphase will not be stored in the database, which means that it will not […]

• ## Wechat payment in Java (2): API V3 wechat platform certificate acquisition and refresh

Time：2021-2-18

1. Preface stayWechat payment in Java (1): API V3 version signature detailsIn this article, Pangge explained the signature of the V3 version API of wechat payment. When we (your own server) request the wechat payment server, we need to use ourAPI certificateAfter signing the parameters, wechat server will verify the signature according to our signature […]

• ## Source code analysis of Android jar / Library apktool.jar

Time：2021-2-4

catalog:Source code analysis of Android jar / Library  Apktool.jar： effect: 1. It is used to unpack APK files into readable SmalI, XML, PNG and other resource files. 2. At the same time, the decoded data is repackaged into APK file. Chestnut: How to use commands 1、apktool d xxx.apk / / decode APK file 2. Apktool […]

• ## AES encryption and decryption (according to the specified secret key)

Time：2021-2-1

Recently, we are calling the third-party interface, which requires AES encryption and the secret key is 16 bits in length. Please record here. First, reference the namespace: using System.IO; using System.Text; using System.Security.Cryptography; /// ///AES encryption (vector free) /// ///Encrypted plaintext ///Key ///Ciphertext public string AESEncrypt(string Data, string Key) { MemoryStream mStream = new MemoryStream(); […]

• ## Encryption and decryption of sequence cipher

Time：2021-1-22

Encryption and decryption of sequence cipher Plaintext, ciphertext and key sequence are composed of individual bits, namely x_{i}, y_{i},s_{i}\in \left\{0,1\right\} Encryption:y_i = e_{s_i}(x_i)\equiv x_i + s_i\ mod\ 2decrypt:x_i = d_{s_i}(y_i)\equiv y_i + s_i\ mod\ 2There are three points about the encryption and decryption functions of sequence cipher Why do encryption and decryption use the same […]

• ## Affine cipher

Time：2021-1-19

Affine cipher The idea of affine cryptography is to multiply the plaintext by a part of the key, and then add the rest of the key. Suppose x, y, a, B, Z_ {26}\\ Decryption can be easily derived from encryption functions a·x+b\equiv y\ mod\ 26\\ a·x\equiv (y-b)\ mod \ 26\\ x\equiv a^{-1}·(y-b)\ mod\ 26 The […]

• ## Password based cryptography (PBE)

Time：2021-1-18

Password based cryptography (PBE) Password based encryption (PBE) is a method of generating key based on password and using the key to encrypt. Encryption and decryption use the same key. According to the user’s own password and salt generated password, let’s first look at the encryption process: The encryption process can be divided into the […]

• ## Summary after reading graphical cryptography

Time：2021-1-15

preface Recently, I used encryption related technology in my work, which is a headache. I’m often confused by a series of concepts such as public key encryption and signature. So I bought the book graphical cryptography to sort out the basic knowledge of cryptography. After reading the basic concept of cryptographic technology have a general […]

• ## PHP encryption and decryption, refer to discuz

Time：2021-1-3

<?php /** *Encryption key */ define(“ENCRYPT_KEY”, “sqltest1179631111”); //Encryption $password = “123456”;$enCryPass = demoEncode($password); var_dump($enCryPass); //Decryption $deCryPass = demoDecode($enCryPass); var_dump($deCryPass); /** *Encryption *@ param$password string password before encryption * @return false|string */ function demoEncode($password) { return authCode($password, “ENCODE”, ENCRYPT_KEY); } /** *Encryption *@ param \$encrypass string password to decrypt * @return false|string */ function […]

• ## Java encrypts and decrypts PDF documents

Time：2020-12-22

preface In daily office, in order to protect the document from being tampered with by others, we can set the opening password for the document, that is, encryption. At the same time, we can also decrypt the encrypted documents so that we can view and edit the documents. This article will demonstrate how to encrypt […]

• ## Interpretation of Java base64 encryption process

Time：2020-12-15

1. Why base 64 The main purpose of base 64 is not to encrypt, but to convert some binary numbers into ordinary characters for easy transmission on the network. Because some binary characters belong to The control character can not be transmitted directly, so it needs to be converted. Since only ASCII characters can be […]

• ## Sorting out the problems encountered in the process of updating and modifying the C code involved in mupdf

Time：2020-12-13

The origin of the problem The project involves PDF reader and needs to add decryption module on the original basis, so previous developers add decryption module on the original logic of reading data flow of mupdf, and then regenerate so library to use with business. (developed during 16 years, unchanged) Recently, when app users open […]