ToBase32 http://seehashrun.blogspot.com/2016/09/base32-encoding-and-decoding-in-c.html Demo at https://dotnetfiddle.net/WsKkJG

Base32-K.cs

public sealed class Base32 {

      // the valid chars for the encoding
      private static string ValidChars = "QAZ2WSX3" + "EDC4RFV5" + "TGB6YHN7" + "UJM8K9LP";

      /// <summary>
      /// Converts an array of bytes to a Base32-k string.
      /// </summary>
      public static string ToBase32String(byte[] bytes) {
            StringBuilder sb = new StringBuilder();         // holds the base32 chars
            byte index;
            int hi = 5;
            int currentByte = 0;

            while (currentByte < bytes.Length) {
                  // do we need to use the next byte?
                  if (hi > 8) {
                        // get the last piece from the current byte, shift it to the right
                        // and increment the byte counter
                        index = (byte)(bytes[currentByte++] >> (hi - 5));
                        if (currentByte != bytes.Length) {
                              // if we are not at the end, get the first piece from
                              // the next byte, clear it and shift it to the left
                              index = (byte)(((byte)(bytes[currentByte] << (16 - hi)) >> 3) | index);
                        }

                        hi -= 3;
                  } else if(hi == 8) { 
                        index = (byte)(bytes[currentByte++] >> 3);
                        hi -= 3; 
                  } else {

                        // simply get the stuff from the current byte
                        index = (byte)((byte)(bytes[currentByte] << (8 - hi)) >> 3);
                        hi += 5;
                  }

                  sb.Append(ValidChars[index]);
            }

            return sb.ToString();
      }


      /// <summary>
      /// Converts a Base32-k string into an array of bytes.
      /// </summary>
      /// <exception cref="System.ArgumentException">
      /// Input string <paramref name="s">s</paramref> contains invalid Base32-k characters.
      /// </exception>
      public static byte[] FromBase32String(string str) {
            int numBytes = str.Length * 5 / 8;
            byte[] bytes = new Byte[numBytes];

            // all UPPERCASE chars
            str = str.ToUpper();

            int bit_buffer;
            int currentCharIndex;
            int bits_in_buffer;

            if (str.Length < 3) {
                  bytes[0] = (byte)(ValidChars.IndexOf(str[0]) | ValidChars.IndexOf(str[1]) << 5);
                  return bytes;
            }

            bit_buffer = (ValidChars.IndexOf(str[0]) | ValidChars.IndexOf(str[1]) << 5);
            bits_in_buffer = 10;
            currentCharIndex = 2;
            for (int i = 0; i < bytes.Length; i++) {
                  bytes[i] = (byte)bit_buffer;
                  bit_buffer >>= 8;
                  bits_in_buffer -= 8;
                  while (bits_in_buffer < 8 && currentCharIndex < str.Length) {
                        bit_buffer |= ValidChars.IndexOf(str[currentCharIndex++]) << bits_in_buffer;
                        bits_in_buffer += 5;
                  }
            }

            return bytes;
      }

}

public static class Base322 {

    private static readonly char[] DIGITS;
    private static readonly int MASK;
    private static readonly int SHIFT;
    private static Dictionary<char, int> CHAR_MAP = new Dictionary<char, int>();
    private const string SEPARATOR = "-";

    static Base322() {
        DIGITS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567".ToCharArray();
        MASK = DIGITS.Length - 1;
        SHIFT = numberOfTrailingZeros(DIGITS.Length);
        for (int i = 0; i < DIGITS.Length; i++) CHAR_MAP[DIGITS[i]] = i;
    }

    private static int numberOfTrailingZeros(int i) {
        // HD, Figure 5-14
        int y;
        if (i == 0) return 32;
        int n = 31;
        y = i << 16; if (y != 0) { n = n - 16; i = y; }
        y = i << 8; if (y != 0) { n = n - 8; i = y; }
        y = i << 4; if (y != 0) { n = n - 4; i = y; }
        y = i << 2; if (y != 0) { n = n - 2; i = y; }
        return n - (int)((uint)(i << 1) >> 31);
    }

    public static byte[] Decode(string encoded) {
        // Remove whitespace and separators
        encoded = encoded.Trim().Replace(SEPARATOR, "");

        // Remove padding. Note: the padding is used as hint to determine how many
        // bits to decode from the last incomplete chunk (which is commented out
        // below, so this may have been wrong to start with).
        encoded = Regex.Replace(encoded, "[=]*$", "");

        // Canonicalize to all upper case
        encoded = encoded.ToUpper();
        if (encoded.Length == 0) {
            return new byte[0];
        }
        int encodedLength = encoded.Length;
        int outLength = encodedLength * SHIFT / 8;
        byte[] result = new byte[outLength];
        int buffer = 0;
        int next = 0;
        int bitsLeft = 0;
        foreach (char c in encoded.ToCharArray()) {
            if (!CHAR_MAP.ContainsKey(c)) {
                throw new DecodingException("Illegal character: " + c);
            }
            buffer <<= SHIFT;
            buffer |= CHAR_MAP[c] & MASK;
            bitsLeft += SHIFT;
            if (bitsLeft >= 8) {
                result[next++] = (byte)(buffer >> (bitsLeft - 8));
                bitsLeft -= 8;
            }
        }
        // We'll ignore leftover bits for now.
        //
        // if (next != outLength || bitsLeft >= SHIFT) {
        //  throw new DecodingException("Bits left: " + bitsLeft);
        // }
        return result;
    }


    public static string Encode(byte[] data, bool padOutput = false) {
        if (data.Length == 0) {
            return "";
        }

        // SHIFT is the number of bits per output character, so the length of the
        // output is the length of the input multiplied by 8/SHIFT, rounded up.
        if (data.Length >= (1 << 28)) {
            // The computation below will fail, so don't do it.
            throw new ArgumentOutOfRangeException("data");
        }

        int outputLength = (data.Length * 8 + SHIFT - 1) / SHIFT;
        StringBuilder result = new StringBuilder(outputLength);

        int buffer = data[0];
        int next = 1;
        int bitsLeft = 8;
        while (bitsLeft > 0 || next < data.Length) {
            if (bitsLeft < SHIFT) {
                if (next < data.Length) {
                    buffer <<= 8;
                    buffer |= (data[next++] & 0xff);
                    bitsLeft += 8;
                } else {
                    int pad = SHIFT - bitsLeft;
                    buffer <<= pad;
                    bitsLeft += pad;
                }
            }
            int index = MASK & (buffer >> (bitsLeft - SHIFT));
            bitsLeft -= SHIFT;
            result.Append(DIGITS[index]);
        }
        if (padOutput) {
            int padding = 8 - (result.Length % 8);
            if (padding > 0) result.Append(new string('=', padding == 8 ? 0 : padding));
        }
        return result.ToString();
    }

    private class DecodingException : Exception {
        public DecodingException(string message) : base(message) {
        }
    }
}

Base32.cs

using System;
using System.Collections.Generic;
using System.Text;
using System.Text.RegularExpressions;
using System.Linq;

public static class Base32
{
    private static readonly char[] DIGITS;
    private static readonly int MASK;
    private static readonly int SHIFT;
    private static Dictionary<char, int> CHAR_MAP = new Dictionary<char, int>();
    private const string SEPARATOR = "-";

    static Base32() {
        DIGITS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567".ToCharArray();
        MASK = DIGITS.Length - 1;
        SHIFT = numberOfTrailingZeros(DIGITS.Length);
        for (int i = 0; i < DIGITS.Length; i++) CHAR_MAP[DIGITS[i]] = i;
    }

    private static int numberOfTrailingZeros(int i) {
        // HD, Figure 5-14
        int y;
        if (i == 0) return 32;
        int n = 31;
        y = i << 16; if (y != 0) { n = n - 16; i = y; }
        y = i << 8; if (y != 0) { n = n - 8; i = y; }
        y = i << 4; if (y != 0) { n = n - 4; i = y; }
        y = i << 2; if (y != 0) { n = n - 2; i = y; }
        return n - (int)((uint)(i << 1) >> 31);
    }

    public static byte[] Decode(string encoded) {
        // Remove whitespace and separators
        encoded = encoded.Trim().Replace(SEPARATOR, "");

        // Remove padding. Note: the padding is used as hint to determine how many
        // bits to decode from the last incomplete chunk (which is commented out
        // below, so this may have been wrong to start with).
        encoded = Regex.Replace(encoded, "[=]*$", "");

        // Canonicalize to all upper case
        encoded = encoded.ToUpper();
        if (encoded.Length == 0) {
            return new byte[0];
        }
        int encodedLength = encoded.Length;
        int outLength = encodedLength * SHIFT / 8;
        byte[] result = new byte[outLength];
        int buffer = 0;
        int next = 0;
        int bitsLeft = 0;
        foreach (char c in encoded.ToCharArray()) {
            if (!CHAR_MAP.ContainsKey(c)) {
                throw new DecodingException("Illegal character: " + c);
            }
            buffer <<= SHIFT;
            buffer |= CHAR_MAP[c] & MASK;
            bitsLeft += SHIFT;
            if (bitsLeft >= 8) {
                result[next++] = (byte)(buffer >> (bitsLeft - 8));
                bitsLeft -= 8;
            }
        }
        // We'll ignore leftover bits for now.
        //
        // if (next != outLength || bitsLeft >= SHIFT) {
        //  throw new DecodingException("Bits left: " + bitsLeft);
        // }
        return result;
    }


    public static string Encode(byte[] data, bool padOutput = false) {
        if (data.Length == 0) {
            return "";
        }

        // SHIFT is the number of bits per output character, so the length of the
        // output is the length of the input multiplied by 8/SHIFT, rounded up.
        if (data.Length >= (1 << 28)) {
            // The computation below will fail, so don't do it.
            throw new ArgumentOutOfRangeException("data");
        }

        int outputLength = (data.Length * 8 + SHIFT - 1) / SHIFT;
        StringBuilder result = new StringBuilder(outputLength);

        int buffer = data[0];
        int next = 1;
        int bitsLeft = 8;
        while (bitsLeft > 0 || next < data.Length) {
            if (bitsLeft < SHIFT) {
                if (next < data.Length) {
                    buffer <<= 8;
                    buffer |= (data[next++] & 0xff);
                    bitsLeft += 8;
                } else {
                    int pad = SHIFT - bitsLeft;
                    buffer <<= pad;
                    bitsLeft += pad;
                }
            }
            int index = MASK & (buffer >> (bitsLeft - SHIFT));
            bitsLeft -= SHIFT;
            result.Append(DIGITS[index]);
        }
        if (padOutput) {
            int padding = 8 - (result.Length % 8);
            if (padding > 0) result.Append(new string('=', padding == 8 ? 0 : padding));
        }
        return result.ToString();
    }

    private class DecodingException : Exception {
        public DecodingException(string message) : base(message) {
        }
    }
}

PasswordGeneratorService.cs

public static class PasswordGeneratorService
{
    /// <summary>
    /// Generates a random password based on the rules passed in the parameters
    /// </summary>
    /// <param name="includeLowercase">Bool to say if lowercase are required</param>
    /// <param name="includeUppercase">Bool to say if uppercase are required</param>
    /// <param name="includeNumeric">Bool to say if numerics are required</param>
    /// <param name="includeSpecial">Bool to say if special characters are required</param>
    /// <param name="includeSpaces">Bool to say if spaces are required</param>
    /// <param name="lengthOfPassword">Length of password required. Should be between 8 and 128</param>
    /// <returns></returns>
    public static string GeneratePassword(bool includeLowercase, bool includeUppercase, bool includeNumeric, bool includeSpecial, bool includeSpaces, int lengthOfPassword)
    {
        const int MAXIMUM_IDENTICAL_CONSECUTIVE_CHARS = 2;
        const string LOWERCASE_CHARACTERS = "abcdefghijklmnopqrstuvwxyz";
        const string UPPERCASE_CHARACTERS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        const string NUMERIC_CHARACTERS = "0123456789";
        const string SPECIAL_CHARACTERS = @"!#$%&*@\";
        const string SPACE_CHARACTER = " ";
        const int PASSWORD_LENGTH_MIN = 8;
        const int PASSWORD_LENGTH_MAX = 128;

        if (lengthOfPassword < PASSWORD_LENGTH_MIN || lengthOfPassword > PASSWORD_LENGTH_MAX)
        {
            return "Password length must be between 8 and 128.";
        }

        string characterSet = "";

        if (includeLowercase)
        {
            characterSet += LOWERCASE_CHARACTERS;
        }

        if (includeUppercase)
        {
            characterSet += UPPERCASE_CHARACTERS;
        }

        if (includeNumeric)
        {
            characterSet += NUMERIC_CHARACTERS;
        }

        if (includeSpecial)
        {
            characterSet += SPECIAL_CHARACTERS;
        }

        if (includeSpaces)
        {
            characterSet += SPACE_CHARACTER;
        }

        char[] password = new char[lengthOfPassword];
        int characterSetLength = characterSet.Length;

        System.Random random = new System.Random();
        for (int characterPosition = 0; characterPosition < lengthOfPassword; characterPosition++)
        {
            password[characterPosition] = characterSet[random.Next(characterSetLength - 1)];

            bool moreThanTwoIdenticalInARow =
                characterPosition > MAXIMUM_IDENTICAL_CONSECUTIVE_CHARS
                && password[characterPosition] == password[characterPosition - 1]
                && password[characterPosition - 1] == password[characterPosition - 2];

            if (moreThanTwoIdenticalInARow)
            {
                characterPosition--;
            }
        }

        return string.Join(null, password);
    }

    /// <summary>
    /// Checks if the password created is valid
    /// </summary>
    /// <param name="includeLowercase">Bool to say if lowercase are required</param>
    /// <param name="includeUppercase">Bool to say if uppercase are required</param>
    /// <param name="includeNumeric">Bool to say if numerics are required</param>
    /// <param name="includeSpecial">Bool to say if special characters are required</param>
    /// <param name="includeSpaces">Bool to say if spaces are required</param>
    /// <param name="password">Generated password</param>
    /// <returns>True or False to say if the password is valid or not</returns>
    public static bool PasswordIsValid(bool includeLowercase, bool includeUppercase, bool includeNumeric, bool includeSpecial, bool includeSpaces, string password)
    {
        const string REGEX_LOWERCASE = @"[a-z]";
        const string REGEX_UPPERCASE = @"[A-Z]";
        const string REGEX_NUMERIC = @"[\d]";
        const string REGEX_SPECIAL = @"([!#$%&*@\\])+";
        const string REGEX_SPACE = @"([ ])+";

        bool lowerCaseIsValid = !includeLowercase || (includeLowercase && Regex.IsMatch(password, REGEX_LOWERCASE));
        bool upperCaseIsValid = !includeUppercase || (includeUppercase && Regex.IsMatch(password, REGEX_UPPERCASE));
        bool numericIsValid = !includeNumeric || (includeNumeric && Regex.IsMatch(password, REGEX_NUMERIC));
        bool symbolsAreValid = !includeSpecial || (includeSpecial && Regex.IsMatch(password, REGEX_SPECIAL));
        bool spacesAreValid = !includeSpaces || (includeSpaces && Regex.IsMatch(password, REGEX_SPACE));

        return lowerCaseIsValid && upperCaseIsValid && numericIsValid && symbolsAreValid && spacesAreValid;
    }
}

for the viewer:
in short, base32-k.cs is not a standard base32 implementation comply to rfc4648.
https://stackoverflow.com/questions/641361/base32-decoding/7135008,

but still good code :thumb up: