Mnemonic Password Generator

ListExtensions.cs

using System;
using System.Collections.Generic;

namespace Gists
{
	public static class ListExtensions
	{
		public static T GetRandom<T>(this List<T> list, Random random = null)
		{
			random = random ?? new Random();

			return list[random.Next(0, list.Count)];
		}
	}
}

PasswordGenerator.cs

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

namespace Gists
{
	public class PasswordGenerator
	{
		public static string GenerateMnemonic(int passwordLength, int numberAmount, bool mixedCase, int? seed = null)
		{
			var password = new StringBuilder();

			var vowels = new List<char> { 'a', 'e', 'i', 'o', 'e' };
			var consonants = new List<char> { 'b', 'c', 'd', 'f', 'g', 'h', 'k', 'l', 'm', 'n', 'p', 'q', 'r', 's', 't', 'v', 'w', 'x', 'z', 'y' };

			if (mixedCase)
			{
				vowels.AddRange(vowels.Select(char.ToUpper).ToList());
				consonants.AddRange(consonants.Select(char.ToUpper).ToList());
			}

			var random = new Random(seed ?? Environment.TickCount);

			for (var i = 0; i < passwordLength/2; i++)
			{
				password.Append(vowels.GetRandom(random));
				password.Append(consonants.GetRandom(random));
			}

			if (numberAmount == 0)
			{
				return password.ToString();
			}

			var numberPosition = random.Next(2, passwordLength - 2 - numberAmount);

			return string.Concat(
				password.ToString().Substring(0, numberPosition),
				random.Next((int) Math.Pow(10, numberAmount - 1), (int) Math.Pow(10, numberAmount) - 1),
				password.ToString().Substring(numberPosition + numberAmount)
			);
		}
	}
}