我想知道如何在C#中生成一个强大而安全的密码。
我google了一下,在维基百科中看到了这个公式,其中L
是密码的长度,N
是可能的符号数:
另外,我找到了this question,但由于某种原因,方法Membership.GeneratePassword
只返回一个1位数的随机数,绝对没有密码。所有其余的解决方案都非常慢(> = 0.5秒)。
我需要帮助实现这个公式(我不知道从哪里开始)。您也可以建议另一种解决方案或解释GeneratePassword
无效的原因。
答案 0 :(得分:74)
我刚刚在linqpad中尝试了以下内容:
System.Web.Security.Membership.GeneratePassword(25, 10)
这是我收到的密码:
[XTJ_67g.i/ag1rL)6_Yv>*+%
或者,如果这不够安全,请尝试:
System.Web.Security.Membership.GeneratePassword(128, 100)
在运行三次时让我得到以下信息:
|c^.:?m)#q+(]V;}[Z(})/?-;$]+@!|^/8*_9.$&.&!(?=^!Wx?[@%+&-@b;)>N;&+*w[>$2+_$%l;+h+#zhs^{e?&=*(}X_%|:}]]}*X[+)Er%J/-=;Q0{:+=%c7:^$ /:_)hxF+*){2|;(>:*N^+!_&|}B.$})?[V=[+v({-:-@9-Z$j?.[-}(@MHx+}(}Mz_S(7#4}{..>@G|!+++{+C=|_}=+r^@&$0;L*|kz-;$++/N3$=}?;%&]]*/^#^!+ :*{]-x^$g{|?*))_=B@^.#%L;g|+)#[nq}?y(_(m;]S^I$*q=l-[_/?}&-!k^(+[_{Z|&:^%!_)!=p%=)=wYd-#.UP$%s1{*l%+[%?!c+7=@=.;{+M)!^}&d/]{];(&}这不到一秒钟,顺便说一下。框架是你的朋友。
请参阅http://msdn.microsoft.com/en-us/library/system.web.security.membership.generatepassword.aspx
答案 1 :(得分:9)
解决有关该公式的问题:
该公式表示从N个符号的字母表中提取的长度为L的密码等同于从两个符号的字母表中提取的长度为H的密码。因此,如果您有64个符号(例如abc ... xyzABC ... XYZ01 ... 89_!)并且密码长度为10个字符,则可以获得与密码相同的安全性10 log2 64 = 60个字符长从字母“ab”中提取。
“log”是取幂的逆运算。 2到6的功率给你64分,因此64分的“log 2”给你6分。
答案 2 :(得分:8)
不确定我在哪里找到这个,但这里有一个类可以生成高熵,真正随机的字符串,可以用作密码。
using System.Security.Cryptography;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
public class PasswordGenerator
{
public int MinimumLengthPassword { get; private set; }
public int MaximumLengthPassword { get; private set; }
public int MinimumLowerCaseChars { get; private set; }
public int MinimumUpperCaseChars { get; private set; }
public int MinimumNumericChars { get; private set; }
public int MinimumSpecialChars { get; private set; }
public static string AllLowerCaseChars { get; private set; }
public static string AllUpperCaseChars { get; private set; }
public static string AllNumericChars { get; private set; }
public static string AllSpecialChars { get; private set; }
private readonly string _allAvailableChars;
private readonly RandomSecureVersion _randomSecure = new RandomSecureVersion();
private int _minimumNumberOfChars;
static PasswordGenerator()
{
// Define characters that are valid and reject ambiguous characters such as ilo, IO and 1 or 0
AllLowerCaseChars = GetCharRange('a', 'z', exclusiveChars: "ilo");
AllUpperCaseChars = GetCharRange('A', 'Z', exclusiveChars: "IO");
AllNumericChars = GetCharRange('2', '9');
AllSpecialChars = "!@#%*()$?+-=";
}
public PasswordGenerator(
int minimumLengthPassword = 15,
int maximumLengthPassword = 20,
int minimumLowerCaseChars = 2,
int minimumUpperCaseChars = 2,
int minimumNumericChars = 2,
int minimumSpecialChars = 2)
{
if (minimumLengthPassword < 15)
{
throw new ArgumentException("The minimumlength is smaller than 15.",
"minimumLengthPassword");
}
if (minimumLengthPassword > maximumLengthPassword)
{
throw new ArgumentException("The minimumLength is bigger than the maximum length.",
"minimumLengthPassword");
}
if (minimumLowerCaseChars < 2)
{
throw new ArgumentException("The minimumLowerCase is smaller than 2.",
"minimumLowerCaseChars");
}
if (minimumUpperCaseChars < 2)
{
throw new ArgumentException("The minimumUpperCase is smaller than 2.",
"minimumUpperCaseChars");
}
if (minimumNumericChars < 2)
{
throw new ArgumentException("The minimumNumeric is smaller than 2.",
"minimumNumericChars");
}
if (minimumSpecialChars < 2)
{
throw new ArgumentException("The minimumSpecial is smaller than 2.",
"minimumSpecialChars");
}
_minimumNumberOfChars = minimumLowerCaseChars + minimumUpperCaseChars +
minimumNumericChars + minimumSpecialChars;
if (minimumLengthPassword < _minimumNumberOfChars)
{
throw new ArgumentException(
"The minimum length of the password is smaller than the sum " +
"of the minimum characters of all catagories.",
"maximumLengthPassword");
}
MinimumLengthPassword = minimumLengthPassword;
MaximumLengthPassword = maximumLengthPassword;
MinimumLowerCaseChars = minimumLowerCaseChars;
MinimumUpperCaseChars = minimumUpperCaseChars;
MinimumNumericChars = minimumNumericChars;
MinimumSpecialChars = minimumSpecialChars;
_allAvailableChars =
OnlyIfOneCharIsRequired(minimumLowerCaseChars, AllLowerCaseChars) +
OnlyIfOneCharIsRequired(minimumUpperCaseChars, AllUpperCaseChars) +
OnlyIfOneCharIsRequired(minimumNumericChars, AllNumericChars) +
OnlyIfOneCharIsRequired(minimumSpecialChars, AllSpecialChars);
}
private string OnlyIfOneCharIsRequired(int minimum, string allChars)
{
return minimum > 0 || _minimumNumberOfChars == 0 ? allChars : string.Empty;
}
public string Generate()
{
var lengthOfPassword = _randomSecure.Next(MinimumLengthPassword, MaximumLengthPassword);
// Get the required number of characters of each catagory and
// add random charactes of all catagories
var minimumChars = GetRandomString(AllLowerCaseChars, MinimumLowerCaseChars) +
GetRandomString(AllUpperCaseChars, MinimumUpperCaseChars) +
GetRandomString(AllNumericChars, MinimumNumericChars) +
GetRandomString(AllSpecialChars, MinimumSpecialChars);
var rest = GetRandomString(_allAvailableChars, lengthOfPassword - minimumChars.Length);
var unshuffeledResult = minimumChars + rest;
// Shuffle the result so the order of the characters are unpredictable
var result = unshuffeledResult.ShuffleTextSecure();
return result;
}
private string GetRandomString(string possibleChars, int lenght)
{
var result = string.Empty;
for (var position = 0; position < lenght; position++)
{
var index = _randomSecure.Next(possibleChars.Length);
result += possibleChars[index];
}
return result;
}
private static string GetCharRange(char minimum, char maximum, string exclusiveChars = "")
{
var result = string.Empty;
for (char value = minimum; value <= maximum; value++)
{
result += value;
}
if (!string.IsNullOrEmpty(exclusiveChars))
{
var inclusiveChars = result.Except(exclusiveChars).ToArray();
result = new string(inclusiveChars);
}
return result;
}
}
internal static class Extensions
{
private static readonly Lazy<RandomSecureVersion> RandomSecure =
new Lazy<RandomSecureVersion>(() => new RandomSecureVersion());
public static IEnumerable<T> ShuffleSecure<T>(this IEnumerable<T> source)
{
var sourceArray = source.ToArray();
for (int counter = 0; counter < sourceArray.Length; counter++)
{
int randomIndex = RandomSecure.Value.Next(counter, sourceArray.Length);
yield return sourceArray[randomIndex];
sourceArray[randomIndex] = sourceArray[counter];
}
}
public static string ShuffleTextSecure(this string source)
{
var shuffeldChars = source.ShuffleSecure().ToArray();
return new string(shuffeldChars);
}
}
internal class RandomSecureVersion
{
//Never ever ever never use Random() in the generation of anything that requires true security/randomness
//and high entropy or I will hunt you down with a pitchfork!! Only RNGCryptoServiceProvider() is safe.
private readonly RNGCryptoServiceProvider _rngProvider = new RNGCryptoServiceProvider();
public int Next()
{
var randomBuffer = new byte[4];
_rngProvider.GetBytes(randomBuffer);
var result = BitConverter.ToInt32(randomBuffer, 0);
return result;
}
public int Next(int maximumValue)
{
// Do not use Next() % maximumValue because the distribution is not OK
return Next(0, maximumValue);
}
public int Next(int minimumValue, int maximumValue)
{
var seed = Next();
// Generate uniformly distributed random integers within a given range.
return new Random(seed).Next(minimumValue, maximumValue);
}
}
在你的代码中消费:
var generator = new PasswordGenerator();
string password = generator.Generate();
Console.WriteLine(password);
答案 3 :(得分:6)
我不知道这是否会对你有所帮助,但这就是我想要生成随机密码时所使用的密码。它的实施/理解快速而简单,并不像通过以上会员提供者那样过度杀伤......
private string Token(byte Length) {
char[] Chars = new char[] {
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9'
};
string String = string.Empty;
Random Random = new Random();
for (byte a = 0; a < Length; a++) {
String += Chars[Random.Next(0, 61)];
};
return (String);
}
答案 4 :(得分:1)
为什么不用一些字符填充数组并随机选择其中一些字符。您可以将它们分组,以确保包含字母数字和特殊字符。
你还需要选择一个合适的长度以及要包含的每组角色中的多少,这就是它。我认为你不需要一些复杂的公式。
答案 5 :(得分:1)
对于不允许用户生成密码的系统,实际上非常简单:任何密码都是安全的,因为它很长。当然,不计算那些将其贴在监视器上的人等等。
您可能希望最大化生成密码的字符集。但限制生成的密码会大大减少搜索空间,从而使密码更少安全。同样,这仅在用户无法选择自己的密码时才有效。
如果您同时处理生成的密码和用户创建的密码,那么显然所有的赌注都会关闭。然后,您可能希望生成密码的方式使其尽可能多地使用来自不同类的字符,类似于用户选择的强密码。理想情况下,它应该符合用户创建的密码必须传递的相同约束(如果有的话)。
答案 6 :(得分:1)
Guid.NewGuid().ToString();
怎么样?
答案 7 :(得分:0)
我自己使用Guid :),并在登录后让用户编辑密码