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DecimalEncoder

This library encodes numeric values (and byte arrays) using a string encoding map. Supported numeric types are:

  • int (32 bit signed positive integer)
  • uint (32 bit unsigned integer)
  • long (64 bit signed positive integer)
  • ulong (64 bit unsigned integer)
  • decimal (unsigned positive unscaled)
  • BigInteger (any size unsigned integer)

Byte arrays will be converted to a BigInteger for encoding.

The encoding uses division for finding the encoding map index and compressing the result. The same will run backward for decoding using multiplication.

How to get it

This library is available as NuGet package.

Usage

// Encode a value
string encoded = RandomNumberGenerator.GetInt32().EncodeDecimal();
Console.WriteLine(encoded);

// Decode an encoded value
int decoded = encoded.ToDecodedInteger();
Console.WriteLine(decoded);

// Create a random value
(decoded, encoded) = DecimalEncoder.CreateRandomInteger();
Console.WriteLine(encoded);
Console.WriteLine(decoded);

Encoding

Please note that encoding isn't encryption. This encoding is WAY more slower than base64 encoding, while the decoding is pretty fast, and the encoded value might be smaller than the original (compression instead of expansion).

I noticed that the length of the encoding map does effect the encoding speed for the different numeric types. For example, the built in encoding maps are fast for all types except decimal, where the encoding takes about 5 times longer (see the test runtimes). The encoding performance depends on the availability of optimized low level number division algorithms and the used divisor (the encoding maps length will be used), and it may also be different with different CPUs or operating systems.

Encoding maps

There are several encoding maps predefined (accessable using the DecimalEncodingMap enumeration):

  • Normal: decimals 0-9, letters a-z and A-Z and basic special characters
  • Simple: decimals 0-9 and letters a-z and A-Z
  • Extended: decimals 0-9, letters a-z and A-Z, more special characters and umlauts
  • Safe: decimals 2-9 and letters a-z (without b, c, d, i, j, l, o, p, u, v) and A-Z (without C, I, O, Q, U, V)
  • SafeExtended: decimals 2-9, letters a-z (without b, c, d, i, j, l, o, p, u, v) and A-Z (without C, I, O, Q, U, V) and some basic special characters

The "Safe" encoding maps are designed to avoid symbols that may be confounded with other similar looking symbols.

You're free to use any individual encoding map. An encoding map contains the symbol list to use, where every symbol needs to be unique.