asp.net 生成随机密码的具体代码

public static class RandomPassword   {       // Define default min and max password lengths.       private static int DEFAULT_MIN_PASSWORD_LENGTH = 8;       private static int DEFAULT_MAX_PASSWORD_LENGTH = 10;       // Define supported password characters divided into groups.       private static string PASSWORD_CHARS_LCASE = "abcdefgijkmnopqrstwxyz";       private static string PASSWORD_CHARS_UCASE = "ABCDEFGHJKLMNPQRSTWXYZ";       private static string PASSWORD_CHARS_NUMERIC = "23456789";       private static string PASSWORD_CHARS_SPECIAL = "*$-+?_&=!%{}/";       /// <summary>       /// Generates a random password.       /// </summary>       /// <returns>       /// Randomly generated password.       /// </returns>       /// <remarks>       /// The length of the generated password will be determined at       /// random. It will be no shorter than the minimum default and       /// no longer than maximum default.       /// </remarks>       public static string Generate()       {           return Generate(DEFAULT_MIN_PASSWORD_LENGTH,                           DEFAULT_MAX_PASSWORD_LENGTH);       }       /// <summary>       /// Generates a random password of the exact length.       /// </summary>       /// <param name="length">       /// Exact password length.       /// </param>       /// <returns>       /// Randomly generated password.       /// </returns>       public static string Generate(int length)       {           return Generate(length, length);       }       /// <summary>       /// Generates a random password.       /// </summary>       /// <param name="minLength">       /// Minimum password length.       /// </param>       /// <param name="maxLength">       /// Maximum password length.       /// </param>       /// <returns>       /// Randomly generated password.       /// </returns>       /// <remarks>       /// The length of the generated password will be determined at       /// random and it will fall with the range determined by the       /// function parameters.       /// </remarks>       public static string Generate(int minLength,                                     int maxLength)       {           // Make sure that input parameters are valid.           if (minLength <= 0 || maxLength <= 0 || minLength > maxLength)               return null;           // Create a local array containing supported password characters           // grouped by types. You can remove character groups from this           // array, but doing so will weaken the password strength.           char[][] charGroups = new char[][]       {           PASSWORD_CHARS_LCASE.ToCharArray(),           PASSWORD_CHARS_UCASE.ToCharArray(),           PASSWORD_CHARS_NUMERIC.ToCharArray(),           PASSWORD_CHARS_SPECIAL.ToCharArray()       };           // Use this array to track the number of unused characters in each           // character group.           int[] charsLeftInGroup = new int[charGroups.Length];           // Initially, all characters in each group are not used.           for (int i = 0; i < charsLeftInGroup.Length; i++)               charsLeftInGroup[i] = charGroups[i].Length;           // Use this array to track (iterate through) unused character groups.           int[] leftGroupsOrder = new int[charGroups.Length];           // Initially, all character groups are not used.           for (int i = 0; i < leftGroupsOrder.Length; i++)               leftGroupsOrder[i] = i;           // Because we cannot use the default randomizer, which is based on the           // current time (it will produce the same "random" number within a           // second), we will use a random number generator to seed the           // randomizer.           // Use a 4-byte array to fill it with random bytes and convert it then           // to an integer value.           byte[] randomBytes = new byte[4];           // Generate 4 random bytes.           RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();           rng.GetBytes(randomBytes);           // Convert 4 bytes into a 32-bit integer value.           int seed = (randomBytes[0] & 0x7f) << 24 |                       randomBytes[1] << 16 |                       randomBytes[2] << 8 |                       randomBytes[3];           Random random = new Random(seed);           char[] password = null;           // Allocate appropriate memory for the password.           if (minLength < maxLength)               password = new char[random.Next(minLength, maxLength + 1)];           else               password = new char[minLength];           // Index of the next character to be added to password.           int nextCharIdx;           // Index of the next character group to be processed.           int nextGroupIdx;           // Index which will be used to track not processed character groups.           int nextLeftGroupsOrderIdx;           // Index of the last non-processed character in a group.           int lastCharIdx;           // Index of the last non-processed group.           int lastLeftGroupsOrderIdx = leftGroupsOrder.Length - 1;           // Generate password characters one at a time.           for (int i = 0; i < password.Length; i++)           {               // If only one character group remained unprocessed, process it;               // otherwise, pick a random character group from the unprocessed               // group list. To allow a special character to appear in the               // first position, increment the second parameter of the Next               // function call by one, i.e. lastLeftGroupsOrderIdx + 1.               if (lastLeftGroupsOrderIdx == 0)                   nextLeftGroupsOrderIdx = 0;               else                   nextLeftGroupsOrderIdx = random.Next(0,                                                        lastLeftGroupsOrderIdx);               // Get the actual index of the character group, from which we will               // pick the next character.               nextGroupIdx = leftGroupsOrder[nextLeftGroupsOrderIdx];               // Get the index of the last unprocessed characters in this group.               lastCharIdx = charsLeftInGroup[nextGroupIdx] - 1;                //http://www.unitymanual.com/forum76.html unity3d游戏               // If only one unprocessed character is left, pick it; otherwise,               // get a random character from the unused character list.               if (lastCharIdx == 0)                   nextCharIdx = 0;               else                   nextCharIdx = random.Next(0, lastCharIdx + 1);               // Add this character to the password.               password[i] = charGroups[nextGroupIdx][nextCharIdx];               // If we processed the last character in this group, start over.               if (lastCharIdx == 0)                   charsLeftInGroup[nextGroupIdx] =                                             charGroups[nextGroupIdx].Length;               // There are more unprocessed characters left.               else               {                   // Swap processed character with the last unprocessed character                   // so that we don't pick it until we process all characters in                   // this group.                   if (lastCharIdx != nextCharIdx)                   {                       char temp = charGroups[nextGroupIdx][lastCharIdx];                       charGroups[nextGroupIdx][lastCharIdx] =                                   charGroups[nextGroupIdx][nextCharIdx];                       charGroups[nextGroupIdx][nextCharIdx] = temp;                   }                   // Decrement the number of unprocessed characters in                   // this group.                   charsLeftInGroup[nextGroupIdx]--;               }               //http://www.unitymanual.com/sitemap.xml               // If we processed the last group, start all over.               if (lastLeftGroupsOrderIdx == 0)                   lastLeftGroupsOrderIdx = leftGroupsOrder.Length - 1;               // There are more unprocessed groups left.               else               {                   // Swap processed group with the last unprocessed group                   // so that we don't pick it until we process all groups.                   if (lastLeftGroupsOrderIdx != nextLeftGroupsOrderIdx)                   {                       int temp = leftGroupsOrder[lastLeftGroupsOrderIdx];                       leftGroupsOrder[lastLeftGroupsOrderIdx] =                                   leftGroupsOrder[nextLeftGroupsOrderIdx];                       leftGroupsOrder[nextLeftGroupsOrderIdx] = temp;                   }                   // Decrement the number of unprocessed groups.                   lastLeftGroupsOrderIdx--;               }           }           // Convert password characters into a string and return the result.           return new string(password);       }   }