How do I encode and decode a base64 string

Question

How do I return a base64 encoded string given a string  How do I decode a base64 encoded string into a string

User · Answer

A slight variation on andrew fox answer  as the string to decode might not be a correct base64 encoded string   using System   namespace Service Support       public static class Base64               public static string ToBase64 this System Text Encoding encoding  string text                        if  text    null                                return null                             byte   textAsBytes   encoding GetBytes text               return Convert ToBase64String textAsBytes                      public static bool TryParseBase64 this System Text Encoding encoding  string encodedText  out string decodedText                        if  encodedText    null                                decodedText   null                  return false                             try                               byte   textAsBytes   Convert FromBase64String encodedText                   decodedText   encoding GetString textAsBytes                   return true                            catch  Exception                                decodedText   null                  return false

User · Answer

Encode  public static string Base64Encode string plainText      var plainTextBytes   System Text Encoding UTF8 GetBytes plainText     return System Convert ToBase64String plainTextBytes       Decode  public static string Base64Decode string base64EncodedData      var base64EncodedBytes   System Convert FromBase64String base64EncodedData     return System Text Encoding UTF8 GetString base64EncodedBytes

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URL safe Base64 Encoding Decoding  public static class Base64Url       public static string Encode string text                return Convert ToBase64String Encoding UTF8 GetBytes text   TrimEnd      Replace       -                Replace                       public static string Decode string text                text   text Replace           Replace  -                 switch  text Length   4                        case 2                  text                          break              case 3                  text                         break                    return Encoding UTF8 GetString Convert FromBase64String text

User · Answer

For those that simply want to encode decode individual base64 digits   public static int DecodeBase64Digit char digit  string digit62     -     string digit63                if  digit  gt    A   amp  amp  digit  lt    Z   return digit -  A       if  digit  gt    a   amp  amp  digit  lt    z   return digit    26 -  a        if  digit  gt    0   amp  amp  digit  lt    9   return digit    52 -  0        if  digit62 IndexOf digit   gt  -1   return 62      if  digit63 IndexOf digit   gt  -1   return 63      return -1     public static char EncodeBase64Digit int digit  char digit62        char digit63              digit  amp   63      if  digit  lt  52          return  char  digit  lt  26   digit    A    digit     a  - 26        else if  digit  lt  62          return  char  digit     0  - 52        else         return digit    62   digit62   digit63      There are various versions of Base64 that disagree about what to use for digits 62 and 63  so DecodeBase64Digit can tolerate several of these

User · Answer

Based on the answers by Andrew Fox and Cebe  I turned it around and made them string extensions instead of Base64String extensions   public static class StringExtensions       public static string ToBase64 this string text                return ToBase64 text  Encoding UTF8              public static string ToBase64 this string text  Encoding encoding                if  string IsNullOrEmpty text                         return text                     byte   textAsBytes   encoding GetBytes text           return Convert ToBase64String textAsBytes              public static bool TryParseBase64 this string text  out string decodedText                return TryParseBase64 text  Encoding UTF8  out decodedText              public static bool TryParseBase64 this string text  Encoding encoding  out string decodedText                if  string IsNullOrEmpty text                         decodedText   text              return false                     try                       byte   textAsBytes   Convert FromBase64String text               decodedText   encoding GetString textAsBytes               return true                    catch  Exception                        decodedText   null              return false

User · Answer

I m sharing my implementation with some neat features    uses Extension Methods for Encoding class  Rationale is that someone may need to support different types of encodings  not only UTF8    Another improvement is failing gracefully with null result for null entry - it s very useful in real life scenarios and supports equivalence for X decode encode X      Remark  Remember that to use Extension Method you have to     import the namespace with using keyword  in this case using MyApplication Helpers Encoding    Code   namespace MyApplication Helpers Encoding       public static class EncodingForBase64               public static string EncodeBase64 this System Text Encoding encoding  string text                        if  text    null                                return null                             byte   textAsBytes   encoding GetBytes text               return System Convert ToBase64String textAsBytes                      public static string DecodeBase64 this System Text Encoding encoding  string encodedText                        if  encodedText    null                                return null                             byte   textAsBytes   System Convert FromBase64String encodedText               return encoding GetString textAsBytes                       Usage example   using MyApplication Helpers Encoding          namespace ConsoleApplication1       class Program               static void Main string   args                        Test1                Test2                       static void Test1                         string textEncoded   System Text Encoding UTF8 EncodeBase64  test1                   System Diagnostics Debug Assert textEncoded     dGVzdDEuLi4                  string textDecoded   System Text Encoding UTF8 DecodeBase64 textEncoded               System Diagnostics Debug Assert textDecoded     test1                          static void Test2                         string textEncoded   System Text Encoding UTF8 EncodeBase64 null               System Diagnostics Debug Assert textEncoded    null                string textDecoded   System Text Encoding UTF8 DecodeBase64 textEncoded               System Diagnostics Debug Assert textDecoded    null

User · Answer

One liner code  Note  Use System and System Text directives  Encode  string encodedStr   Convert ToBase64String Encoding UTF8 GetBytes  quot inputStr quot      Decode  string inputStr   Encoding UTF8 GetString Convert FromBase64String encodedStr

User · Answer

using System      using System Text       public static class Base64Conversions               public static string EncodeBase64 this string text  Encoding encoding   null                         if  text    null  return null               encoding   encoding    Encoding UTF8              var bytes   encoding GetBytes text               return Convert ToBase64String bytes                      public static string DecodeBase64 this string encodedText  Encoding encoding   null                        if  encodedText    null  return null               encoding   encoding    Encoding UTF8              var bytes   Convert FromBase64String encodedText               return encoding GetString bytes                     Usage      var text    Sample Text       var base64   text EncodeBase64        base64   text EncodeBase64 Encoding UTF8     or with Encoding

User · Answer

You can display it like this   var strOriginal   richTextBox1 Text   byte   byt   System Text Encoding ASCII GetBytes strOriginal       convert the byte array to a Base64 string string strModified   Convert ToBase64String byt    richTextBox1 Text        strModified    Now  converting it back   var base64EncodedBytes   System Convert FromBase64String richTextBox1 Text    richTextBox1 Text        System Text Encoding ASCII GetString base64EncodedBytes   MessageBox Show  Done Converting   ASCII from base64       I hope this helps

User · Answer

You can use below routine to convert string to base64 format  public static string ToBase64 string s        byte   buffer   System Text Encoding Unicode GetBytes s       return System Convert ToBase64String buffer       Also you can use very good online tool OnlineUtility in to encode string in base64 format

[c#] How do I encode and decode a base64 string?

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