Calculate a MD5 hash from a string

Question

I use the following C  code to calculate a MD5 hash from a string  It works well and generates a 32-character hex string like this  900150983cd24fb0d6963f7d28e17f72  string sSourceData  byte   tmpSource  byte   tmpHash  sSourceData    MySourceData      Create a byte array from source data  tmpSource   ASCIIEncoding ASCII GetBytes sSourceData   tmpHash   new MD5CryptoServiceProvider   ComputeHash tmpSource       and then convert tmpHash to string      Is there a way to use code like this to generate a 16-character hex string  or 12-character string   A 32-character hex string is good but I think it ll be boring for the customer to enter the code

User · Answer

Idk anything about 16 character hex strings....

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

But here is mine for creating MD5 hash in one line.

string hash = BitConverter.ToString(MD5.Create().ComputeHash(Encoding.ASCII.GetBytes("THIS STRING TO MD5"))).Replace("-","");

User · Answer

I d like to offer an alternative that appears to perform at least 10  faster than craigdfrench s answer in my tests   NET 4 7 2    public static string GetMD5Hash string text        using   var md5   MD5 Create                   byte   computedHash   md5 ComputeHash  Encoding UTF8 GetBytes text             return new System Runtime Remoting Metadata W3cXsd2001 SoapHexBinary computedHash  ToString              If you prefer to have using System Runtime Remoting Metadata W3cXsd2001  at the top  the method body can be made an easier to read one-liner   using   var md5   MD5 Create           return new SoapHexBinary  md5 ComputeHash  Encoding UTF8 GetBytes text      ToString        Obvious enough  but for completeness  in OP s context it would be used as   sSourceData    MySourceData   tmpHash   GetMD5Hash sSourceData

User · Answer

Depends entirely on what you are trying to achieve  Technically  you could just take the first 12 characters from the result of the MD5 hash  but the specification of MD5 is to generate a 32 char one   Reducing the size of the hash reduces the security  and increases the chance of collisions and the system being broken   Perhaps if you let us know more about what you are trying to achieve we may be able to assist more

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System Text StringBuilder hash   new System Text StringBuilder            System Security Cryptography MD5CryptoServiceProvider md5provider   new System Security Cryptography MD5CryptoServiceProvider            byte   bytes   md5provider ComputeHash new System Text UTF8Encoding   GetBytes YourEntryString             for  int i   0  i  lt  bytes Length  i                          hash Append bytes i  ToString  x2       lowerCase  X2 if uppercase desired                   return hash ToString

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StringBuilder sb  new StringBuilder    for  int i   0  i  lt  tmpHash Length  i         sb Append tmpHash i  ToString  x2

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public static string Md5 string input  bool isLowercase   false                        using  MD5 md5   MD5 Create                                  byte   byteHash   md5 ComputeHash Encoding UTF8 GetBytes input                    string hash   BitConverter ToString byteHash  Replace  quot - quot    quot  quot                    return  isLowercase    hash ToLower     hash

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Extending Anant Dabhi s answer a helper method  using System Text   namespace XYZ Helpers       public static class EncryptionHelper               public static string ToMD5 this string input                           Use input string to calculate MD5 hash             using  System Security Cryptography MD5 md5   System Security Cryptography MD5 Create                                  byte   inputBytes   System Text Encoding ASCII GetBytes input                   byte   hashBytes   md5 ComputeHash inputBytes                       Convert the byte array to hexadecimal string                 StringBuilder sb   new StringBuilder                    for  int i   0  i  lt  hashBytes Length  i                                          sb Append hashBytes i  ToString  quot X2 quot                                       return sb ToString

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I suppose it is better to use UTF-8 encoding in the string MD5   public static string MD5 this string s        using  var provider   System Security Cryptography MD5 Create                  StringBuilder builder   new StringBuilder                                        foreach  byte b in provider ComputeHash Encoding UTF8 GetBytes s                builder Append b ToString  x2   ToLower              return builder ToString

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given  a password in a string string password     1234abcd       byte array representation of that string byte   encodedPassword   new UTF8Encoding   GetBytes password       need MD5 to calculate the hash byte   hash     HashAlgorithm  CryptoConfig CreateFromName  MD5    ComputeHash encodedPassword       string representation  similar to UNIX format  string encoded   BitConverter ToString hash        without dashes     Replace  -   string Empty        make lowercase     ToLower        encoded contains the hash you want

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A faster alternative of existing answer for  NET Core 2 1 and higher   public static string CreateMD5 string s        using  System Security Cryptography MD5 md5   System Security Cryptography MD5 Create                  var encoding   Encoding ASCII          var data   encoding GetBytes s            Span lt byte gt  hashBytes   stackalloc byte 16           md5 TryComputeHash data  hashBytes  out int written           if written    hashBytes Length              throw new OverflowException              Span lt char gt  stringBuffer   stackalloc char 32           for  int i   0  i  lt  hashBytes Length  i                          hashBytes i  TryFormat stringBuffer Slice 2   i   out     x2                      return new string stringBuffer             You can optimize it even more if you are sure that your strings are small enough and replace encoding GetBytes by unsafe int GetBytes ReadOnlySpan chars  Span bytes  alternative

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Here is my utility function for UTF8  which can be replaced with ASCII if desired      public static byte   MD5Hash string message                return MD5 Create   ComputeHash Encoding UTF8 GetBytes message

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Was trying to create a string representation of MD5 hash using LINQ  however  none of the answers were LINQ solutions  therefore adding this to the smorgasbord of available solutions    string result  using  MD5 hash   MD5 Create          result   String Join                           from ba in hash ComputeHash                       Encoding UTF8 GetBytes observedText                     select ba ToString  x2

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This solution requires c  8 and takes advantage of Span lt T gt   Note  you would still need to call  Replace  -   string Empty  ToLowerInvariant   to format the result if necessary   public static string CreateMD5 ReadOnlySpan lt char gt  input        var encoding   System Text Encoding UTF8      var inputByteCount   encoding GetByteCount input       using var md5   System Security Cryptography MD5 Create         Span lt byte gt  bytes   inputByteCount  lt  1024           stackalloc byte inputByteCount            new byte inputByteCount       Span lt byte gt  destination   stackalloc byte md5 HashSize   8        encoding GetBytes input  bytes           checking the result is not required because this only returns false if   destination Length  lt  HashSizeValue 8    which is never true in this case     md5 TryComputeHash bytes  destination  out int  bytesWritten        return BitConverter ToString destination ToArray

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Support string and file stream   examples  string hashString   EasyMD5 Hash  My String     string hashFile   EasyMD5 Hash System IO File OpenRead  myFile txt       -     class EasyMD5                       private static string GetMd5Hash byte   data                                StringBuilder sBuilder   new StringBuilder                    for  int i   0  i  lt  data Length  i                        sBuilder Append data i  ToString  x2                     return sBuilder ToString                               private static bool VerifyMd5Hash byte   data  string hash                                return 0    StringComparer OrdinalIgnoreCase Compare GetMd5Hash data   hash                              public static string Hash string data                                using  var md5   MD5 Create                        return GetMd5Hash md5 ComputeHash Encoding UTF8 GetBytes data                               public static string Hash FileStream data                                using  var md5   MD5 Create                        return GetMd5Hash md5 ComputeHash data                               public static bool Verify string data  string hash                                using  var md5   MD5 Create                        return VerifyMd5Hash md5 ComputeHash Encoding UTF8 GetBytes data    hash                              public static bool Verify FileStream data  string hash                                using  var md5   MD5 Create                        return VerifyMd5Hash md5 ComputeHash data   hash

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You can use Convert ToBase64String to convert 16 byte output of MD5 to a  24 char string  A little bit better without reducing security   j9JIbSY8HuT89 pwdC8jlw   for your example

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A MD5 hash is 128 bits  so you can t represent it in hex with less than 32 characters

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As per MSDN Create MD5  public static string CreateMD5 string input           Use input string to calculate MD5 hash     using  System Security Cryptography MD5 md5   System Security Cryptography MD5 Create                  byte   inputBytes   System Text Encoding ASCII GetBytes input           byte   hashBytes   md5 ComputeHash inputBytes               Convert the byte array to hexadecimal string         StringBuilder sb   new StringBuilder            for  int i   0  i  lt  hashBytes Length  i                          sb Append hashBytes i  ToString  quot X2 quot                       return sb ToString

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https   docs microsoft com en-us dotnet api system security cryptography md5 view netframework-4 7 2  using System  using System Security Cryptography  using System Text       static string GetMd5Hash string input                                using  MD5 md5Hash   MD5 Create                                              Convert the input string to a byte array and compute the hash                      byte   data   md5Hash ComputeHash Encoding UTF8 GetBytes input                            Create a new Stringbuilder to collect the bytes                        and create a string                      StringBuilder sBuilder   new StringBuilder                            Loop through each byte of the hashed data                         and format each one as a hexadecimal string                      for  int i   0  i  lt  data Length  i                                                  sBuilder Append data i  ToString  x2                                                   Return the hexadecimal string                      return sBuilder ToString                                                    Verify a hash against a string              static bool VerifyMd5Hash string input  string hash                                   Hash the input                  string hashOfInput   GetMd5Hash input                       Create a StringComparer an compare the hashes                  StringComparer comparer   StringComparer OrdinalIgnoreCase                   return 0    comparer Compare hashOfInput  hash

[c#] Calculate a MD5 hash from a string

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