一个帮助类，实现将密码加盐加密保存，简单修改即可用于生产环境。

SecretEncryptor.cs

using System;
using System.Security.Cryptography;
using System.Text;

namespace Demo
{
    /// <summary>
    /// 密码加密帮助类
    /// 使用特定算法（SHA256或SHA512和盐值对密码进行加密）
    /// 将密码以{hash,salt,algorithm}的形式储存以避免明文储存机密带来的安全风险
    /// 此算法能保护在数据泄露事件发生后密码原文不被窃取，同时能一定程度上应对彩虹表的攻击
    /// 加密后的密码将永远不可读，只能用于验证
    /// </summary>
    public static class SecretEncryptor
    {
        /// <summary>
        /// 默认的加密算法，当前为 SHA256
        /// </summary>
        public const string DEFAULT_ALGORITHM = SHA256;
        /// <summary>
        /// SHA245加密算法
        /// </summary>
        public const string SHA256 = "SHA256";
        /// <summary>
        /// SHA512加密算法
        /// </summary>
        public const string SHA512 = "SHA512";

        /// <summary>
        /// 加密密码
        /// </summary>
        /// <param name="rawSecret">原始密码</param>
        /// <param name="salt">盐值，请在加密新的密码时使用新的盐值</param>
        /// <param name="algorithm">加密算法</param>
        /// <returns>加密后的字符串</returns>
        public static byte[] Encode(string rawSecret, string salt, string algorithm)
        {
            return algorithm switch
            {
                SHA256 => Sha256(Mix(rawSecret, salt)),
                SHA512 => Sha512(Mix(rawSecret, salt)),
                _ => throw new NotImplementedException($"未知的加密算法：{algorithm}"),
            };
        }

        private static byte[] Mix(string rawSecret, string salt) => Encoding.UTF8.GetBytes($"{rawSecret}{{{salt}}}");

        private static byte[] Sha256(byte[] content) => new SHA256Managed().ComputeHash(content);

        private static byte[] Sha512(byte[] content) => new SHA512Managed().ComputeHash(content);

        /// <summary>
        /// 校验密码
        /// </summary>
        /// <param name="storedHash">存储的密码hash</param>
        /// <param name="computedHash">计算出来的密码hash</param>
        /// <returns>密码是否匹配</returns>
        public static bool Verify(byte[] storedHash, byte[] computedHash)
        {
            var diff = storedHash.Length ^ computedHash.Length;
            for (int i = 0; i < storedHash.Length && i < computedHash.Length; i++)
            {
                diff |= storedHash[i] ^ computedHash[i];
            }

            return diff == 0;
        }
    }
}