/// <summary>
/// Generates a random password of the specified <paramref name="length"/> with at least one uppercase letter, one lowercase letter, one special character and one digit.
/// </summary>
/// <param name="length">Length of the password to generate.</param>
/// <returns>Randomly generated password of the specified <paramref name="length"/>.</returns>
/// <exception cref="ArgumentException">A value of less than 8 is specified for the <paramref name="length"/>.</exception>
public static string GeneratePassword(int length)
{
if (length < 8)
{
throw new ArgumentException("Value must be at least 8", "length");
}
// ASCII character ranges:
// Lower case - 97 to 122
// Upper case - 65 to 90
// Special character - 33 to 47
// Digits - 48 to 57
int cursor = 0;
int lower = Random.Int32Between(1, length / 2);
int upper = Random.Int32Between(1, (length - lower) / 2);
int special = Random.Int32Between(1, (length - (lower + upper)) / 2);
int digits = length - (lower + upper + special);
char[] password = new char[length];
for (int i = 0; i < lower; i++)
{
password[cursor] = (char)Random.Int32Between(97, 122);
cursor++;
}
for (int i = 0; i < upper; i++)
{
password[cursor] = (char)Random.Int32Between(65, 90);
cursor++;
}
for (int i = 0; i < special; i++)
{
password[cursor] = (char)Random.Int32Between(33, 47);
cursor++;
}
for (int i = 0; i < digits; i++)
{
password[cursor] = (char)Random.Int32Between(48, 57);
cursor++;
}
// Scramble for more randomness.
List <char> scrambledPassword = new List <char>(password);
scrambledPassword.Scramble();
return(new string(scrambledPassword.ToArray()));
}
