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Encoding And Decoding Files In C++ Builder By Using Bit Shifting

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What is the fastest data encoding and decoding method? Can we use shifting to encode or decode a data or file? Can we use shifting on strings or on binary data? Should we?We’ll try to answer all of these questions.

Bits and bitwise operations

The bit is the most basic unit of information in computing and digital communications. In real all operators are mainly based on Bit Operations which are also called Bitwise Operations. In computer programming, a Bitwise Operation operates on a bit string, a bit array, or a binary numeral (considered as a bit string) at the level of its individual bits, 1s, and 0s. The Bitwise Operation is basic to the higher-level arithmetic operations and it is a fast and simple action because it is directly supported by the processors. Most bitwise operations are presented as two-operand instructions where the result replaces one of the input operands.

Because of all these basics of the microarchitecture of computers, it is very important to know Bitwise Operators. C Programming language is one of the oldest programming languages and a lot of operands, operators in other programming languages got inspiration from this language. C and C++ have the same operators and most of them are the same in other programming languages. We have explained well about operators in general in this Learn How To Use Operators In C++ post before. Now let’s see Bit Shifting and Encoding – Decoding examples.

Bit Shifting Data

One of the Bitwise Operand is the Bit Shifting, the Left Shifting with ‘<<‘ operand, and the Right Shifting>>‘ operand. Bit operations are the fastest operations in machine codes and in C++ because of the microarchitecture of computers as explained above. There are many encoding and decoding methods, also hash coding methods. One of the easiest and the fastest encoding method is Bit Shifting Data. We can use this method to encode and decode data files.

Left Shifting and Right Shifting

For example if c is char we can encode and decode this char by using bit shifting as below,

This works well in lower than 127 char numbers. When shifting we lost the frontier bits (when shifting left we lost left bit or bits and when shifting right we lost right bit or bits). To hold all these bits in a binary data we should do Circular Bit Shifting,

Circular Left Shifting and Circular Right Shifting

If we use Circular Bit Shifting, we never loose any bits when we encode or decode our data. If we want to shift 2 bits from maximum of 8 bits we can do left and right circular bit shifting as below,

Circular Left Shifting and Circular Right Shifting with Complexity

We can add complexity to number of shifting bits by adding (1+i%7) for example,

Bit Shifting Data Files in C++ Builder

For example we can use this Circular Bit Shifting Method with Complexity to Encode and Decode data files in C++ Builder. To do this example in C++ Builder,

  1. Create a new C++ Builder VCL Project and save all files to a project folder
  2. Add 2 Buttons (TButton), set Button1->Caption = “Encode” and Button2->Caption = “Decode”
  3. Add a Memo (TMemo) and OpenDialog (TOpenDialog) component on to form by dragging it from the Palette
  4. Press F12 to switch to code mode and add these headers to your codes as in given example below,

5. Double Click to Button1 ‘Encode’ button and add these lines below to open, encode and save encoded file,

6. Double click to Button2 ‘Decode’ button and add these lines below to open encoded file, decode and save decoded file,

7. Press F9 to compile and run with debugging. Now you can choose a file to encode and encode the *.enc file to decode as *.dec file

encodedecode-9801634

We could use this bit shifting method to protect our data, user names, passwords and similar sensitive items as a fun exercise but bit shifting in this way is a form of security through obscurity. There are industry standard security practices such as salting passwords and using industry standard encryption that provide real security.

Industry standard practices like salting passwords should use powerful cryptographic hash functions such as ones available in modern C++ on Windows (SHA, SHA2, MD5, BobJenkins, etc.). See this Learn To Use Powerful Cryptographic Hash Functions In Modern C++ On Windows (SHA, SHA2, MD5, BobJenkins). Libraries such as IPWorks Encrypt 2020 are available via Embarcadero’s GetIt and offer strong industry standard encryption.


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About author

33+ years of coding with more than 30+ programming languages, mostly C++ on Windows, Android, Mac-OS, iOS, Linux and some other operating systems. Dr. Yilmaz Yoru was born in 1974, Eskisehir-Turkey. He graduated from the department of Mechanical Engineering of Eskisehir Osmangazi University in 1997. One year later he started to work in the same university as an assistant. He received his MSc and PhD degrees from the same department of the same university. He has married and he is a father of a son. Some of his interests are Programming, Thermodynamics, Fluid Mechanics and Artificial Intelligence. He also likes the graphical 2D & 3D design and high-end innovations.

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