C# 密碼複雜度檢查

CheckPasswordComplexity.cs

/// <summary>
/// 檢查密碼強度
/// </summary>
/// <param name="password">密碼</param>
/// <param name="minLength">最小長度</param>
/// <param name="maxLength">最大長度(null則略過檢查)</param>
/// <param name="hasNumber">必須至少有一個數字</param>
/// <param name="hasLetter">必須至少有一個英文字母(不區分大小寫)</param>
/// <param name="hasDiffCaseLetter">必須至少有一個大寫字母及一個小寫字母</param>
/// <param name="hasSpecialChar">必須至少有一個特殊符號</param>
/// <returns>是否通過檢查</returns>
public static bool CheckPasswordComplexity(string password, int minLength = 8,
	int? maxLength = null, bool hasNumber = true, bool hasLetter = true, bool hasDiffCaseLetter = false, bool hasSpecialChar = false)
{
	return CheckPasswordComplexity(password, out string _, minLength,
		maxLength, hasNumber, hasLetter, hasDiffCaseLetter, hasSpecialChar);
}

/// <summary>
/// 檢查密碼強度
/// </summary>
/// <param name="password">密碼</param>
/// <param name="errMsg">錯誤訊息</param>
/// <param name="minLength">最小長度</param>
/// <param name="maxLength">最大長度(null則略過檢查)</param>
/// <param name="hasNumber">必須至少有一個數字</param>
/// <param name="hasLetter">必須至少有一個英文字母(不區分大小寫)</param>
/// <param name="hasDiffCaseLetter">必須至少有一個大寫字母及一個小寫字母</param>
/// <param name="hasSpecialChar">必須至少有一個特殊符號</param>
/// <returns>是否通過檢查</returns>
public static bool CheckPasswordComplexity(string password, out string errMsg, int minLength = 8,
	int? maxLength = null, bool hasNumber = true, bool hasLetter = true, bool hasDiffCaseLetter = false, bool hasSpecialChar = false)
{
	errMsg = "";

	if (string.IsNullOrEmpty(password))
	{
		errMsg = "密碼不得為空！";
		return false;
	}

	if (password.Length < minLength)
	{
		errMsg = $"密碼長度至少為「{minLength}」！";
		return false;
	}

	if (maxLength.HasValue && password.Length > maxLength)
	{
		errMsg = $"密碼長度至多為「{maxLength}」！";
		return false;
	}

	if (hasNumber && !Regex.IsMatch(password, @"\d+"))
	{
		errMsg = "密碼必須包含數字！";
		return false;
	}

	bool lowerSuccess = Regex.IsMatch(password, @"[a-z]");
	bool upperSuccess = Regex.IsMatch(password, @"[A-Z]");

	if (hasLetter)
	{
		if (!(lowerSuccess || upperSuccess))
		{
			errMsg = "密碼必須包含英文字母！";
			return false;
		}
	}

	if (hasDiffCaseLetter)
	{
		if (!(lowerSuccess && upperSuccess))
		{
			errMsg = "密碼必須包含大小寫英文字母！";
			return false;
		}
	}

	if (hasSpecialChar && !Regex.IsMatch(password, @"[ !""#$%&'()*+,-.\/:;<=>?@\[\\\]^_`{|}~]"))
	{
		errMsg = "密碼必須包含特殊字元！";
		return false;
	}

	return errMsg == string.Empty;
}