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  Implementing DESede/ECB/NoPadding cipher algorithm in GoLang

By default, GoLang doesn't provide the ECB mode cipher for DESede though there is CBC mode provided. In cases we need to encrypt/decrypt data with ECB mode, we need to implement those by ourselves. This mode is frequently used when encrypting/decrypting PIN block which is small block data less than 16 bytes. In this post, we will introduce how to implement the DESede/ECB/NoPadding algorithm in GoLang by using the existing cipher support. Here we will not cover how DESede works in detail, instead...

   SECURITY,SAMPLE,GOLANG,DES,DESEDE,3DES     2019-07-29 06:43:50

  Use Java ThreadLocal with caution

According to Oracle documentation, ThreadLocal is a class provides thread-local variables. These variables differ from their normal counterparts in that each thread that accesses one (via its get or set method) has its own, independently initialized copy of the variable. ThreadLocal instances are typically private static fields in classes that wish to associate state with a thread. In short, ThreadLocal variables are variables belong to a thread, not a class or an instance of a class. One common...

   JAVA,MEMORY LEAK, THREADLOCAL     2015-11-03 07:31:57

  Why accessing Java HashMap may cause infinite loop in concurrent environment

HashMap in Java is frequently used to handle key/value pairs. But it is not a good candidate to be used in concurrent environment where ConcurrentHashMap should be used instead. If used in concurrent environment, it may cause lots of unexpected behavior even including make the program getting into an infinite loop situation. To understand how this can happen, let's first discuss how HaspMap works internally. In this post we will use implementation of HashMap before Java 8 as example, Java 8 prov...

   JAVA,HASHMAP,INFINITE LOOP     2020-03-29 01:47:00

  How big is sizeof structure?

First let's see the codes of a structure: struct node{ int a; int b; }; Question : What's sizeof(node)? The answer is very simple, on a 32 bit machine, an int will take 4 bytes and two ints will take 8 bytes. So sizeof(node) is 8. The answer for the above codes is 8, then how about the following structure: struct node{ char a; int b; }; Question : Then what's sizeof(node) now? int takes 4 bytes, char takes 1 bytes, is the answer 5? Now the answer may not be 5, on some mac...

   Data structure alignment, pack     2012-10-29 12:13:37

  Data type in MySQL

For both small free database space and large e-commerce websites, reasonable database table structure design is essential. To achieve this, it requires us to have a full understanding of commonly used data types in database system. Below we share some knowledge about data types in MySQL.1. Numeric typesThe numeric types can be classified as : integer, float and decimal type.The so-called "decimal" refers DECIMAL and NUMERIC, they are of the same type. Strictly speaking it is not a numeric type, ...

   MySQL, Data type,VARCHAR     2013-01-01 10:56:06

  Time to think about supporting max/min functions for integers in GoLang

Sometime back we wrote a post explaining why there is no max/min function support for integers in GoLang, one of the reasons is that no overloading is supported and the function name has been used for other numeric types float64. To solve this problem and make max/min function support integer as well, either GoLang should support overloading like in Java or the same set of functions need to be created in a different package other than standard math. These don't look like good options as overload...

   MIN,MAX,GENERICS,GOLANG     2021-07-24 03:14:42

  Top 10 Go Coding Traps and Tips

Go is currently the most common programming language in cloud development. Though I use it very much in my work, I am still repeating certain mistakes. This article is more a record of these errors, figuring out the causes and solutions so that people who read this article will save themselves time when coming across the same problems. Let’s cut through to the tips. Don’t rely on index var in the for loop The most common mistake we make is that we often create goroutine&nbs...

   TIPS,GOLANG,NIL INTERFACE     2021-07-03 23:45:51

  HeartBleed: Inside the heart, what causes the bleeding?

Just after a few weeks since Apple's famous goto fail bug, there is one bug in OpenSSL which catches the attention from the world again. The bug is named HeartBleed, found in OpenSSL library, a famous open source library supporting lots of  SSL/TLS communication among server/client applications. The reason why this bug catches the attentions from the world is it affects almost all sites which are using the affected OpenSSL library, these includes many applications like Nginx server, some v...

   OpenSSL,HeartBleed     2014-04-09 05:47:30

  Understanding GoLang interface

If goroutine and channel are considered as the foundation for GoLang concurrency, interface would be the key for data types in GoLang. In practical Go programming, almost all data types are built/used around interfaces, interface is the core of GoLang data structures. Go is not a typical OOP language, it has no class and inheritance concept syntactically. But it doesn't mean that there cannot be polymorphism in GoLang. Because of interface, it achieves the same polymorphism effect as in C++, tho...

   INTERFACE,GOLANG     2021-05-15 04:16:42

  The hidden risk of passing slice as function parameter

In Go's source code or other open source libraries, there are lots of cases where a slice pointer is passed to function instead of slice itself. This brings up a doubt why not passing slice directly as its internal is backed by an array pointer to point to underlying data? For example, in log package, the formatHeader function takes a parameter buf as type *[]byte instead of []byte. func (l *Logger) formatHeader(buf *[]byte, t time.Time, file string, line int) {} Let's understand the r...

   GOLANG,SLICE,SLICE POINTER     2020-12-13 06:11:14

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