RFC 3548 (rfc3548) - Page 1 of 13

The Base16, Base32, and Base64 Data Encodings

Alternative Format: Original Text Document
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Network Working Group                                  S. Josefsson, Ed.
Request for Comments: 3548                                     July 2003
Category: Informational


             The Base16, Base32, and Base64 Data Encodings

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2003).  All Rights Reserved.

Abstract

   This document describes the commonly used base 64, base 32, and base
   16 encoding schemes.  It also discusses the use of line-feeds in
   encoded data, use of padding in encoded data, use of non-alphabet
   characters in encoded data, and use of different encoding alphabets.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.  Implementation discrepancies . . . . . . . . . . . . . . . . .  2
       2.1.  Line feeds in encoded data . . . . . . . . . . . . . . .  2
       2.2.  Padding of encoded data  . . . . . . . . . . . . . . . .  3
       2.3.  Interpretation of non-alphabet characters in encoded
             data . . . . . . . . . . . . . . . . . . . . . . . . . .  3
       2.4.  Choosing the alphabet  . . . . . . . . . . . . . . . . .  3
   3.  Base 64 Encoding . . . . . . . . . . . . . . . . . . . . . . .  4
   4.  Base 64 Encoding with URL and Filename Safe Alphabet . . . . .  6
   5.  Base 32 Encoding . . . . . . . . . . . . . . . . . . . . . . .  6
   6.  Base 16 Encoding . . . . . . . . . . . . . . . . . . . . . . .  8
   7.  Illustrations and examples . . . . . . . . . . . . . . . . . .  9
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 10
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
       9.1.  Normative References . . . . . . . . . . . . . . . . . . 11
       9.2.  Informative References . . . . . . . . . . . . . . . . . 11
   10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11
   11. Editor's Address . . . . . . . . . . . . . . . . . . . . . . . 12
   12. Full Copyright Statement . . . . . . . . . . . . . . . . . . . 13






Josefsson                    Informational
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