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diff --git a/ruby/lib/base64.rb b/ruby/lib/base64.rb
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+#
+# = base64.rb: methods for base64-encoding and -decoding stings
+#
+
+# The Base64 module provides for the encoding (#encode64, #strict_encode64,
+# #urlsafe_encode64) and decoding (#decode64, #strict_decode64,
+# #urlsafe_decode64) of binary data using a Base64 representation.
+#
+# == Example
+#
+# A simple encoding and decoding. 
+# 
+#     require "base64"
+#
+#     enc   = Base64.encode64('Send reinforcements')
+#                         # -> "U2VuZCByZWluZm9yY2VtZW50cw==\n" 
+#     plain = Base64.decode64(enc)
+#                         # -> "Send reinforcements"
+#
+# The purpose of using base64 to encode data is that it translates any
+# binary data into purely printable characters.
+
+module Base64
+  module_function
+
+  # Returns the Base64-encoded version of +bin+.
+  # This method complies with RFC 2045.
+  # Line feeds are added to every 60 encoded charactors.
+  #
+  #    require 'base64'
+  #    Base64.encode64("Now is the time for all good coders\nto learn Ruby")
+  #
+  # <i>Generates:</i>
+  #
+  #    Tm93IGlzIHRoZSB0aW1lIGZvciBhbGwgZ29vZCBjb2RlcnMKdG8gbGVhcm4g
+  #    UnVieQ==
+  def encode64(bin)
+    [bin].pack("m")
+  end
+
+  # Returns the Base64-decoded version of +str+.
+  # This method complies with RFC 2045.
+  # Characters outside the base alphabet are ignored.
+  #
+  #   require 'base64'
+  #   str = 'VGhpcyBpcyBsaW5lIG9uZQpUaGlzIG' +
+  #         'lzIGxpbmUgdHdvClRoaXMgaXMgbGlu' +
+  #         'ZSB0aHJlZQpBbmQgc28gb24uLi4K'
+  #   puts Base64.decode64(str)
+  #
+  # <i>Generates:</i>
+  #
+  #    This is line one
+  #    This is line two
+  #    This is line three
+  #    And so on...
+  def decode64(str)
+    str.unpack("m").first
+  end
+
+  # Returns the Base64-encoded version of +bin+.
+  # This method complies with RFC 4648.
+  # No line feeds are added.
+  def strict_encode64(bin)
+    [bin].pack("m0")
+  end
+
+  # Returns the Base64-decoded version of +str+.
+  # This method complies with RFC 4648.
+  # ArgumentError is raised if +str+ is incorrectly padded or contains
+  # non-alphabet characters.  Note that CR or LF are also rejected.
+  def strict_decode64(str)
+    str.unpack("m0").first
+  end
+
+  # Returns the Base64-encoded version of +bin+.
+  # This method complies with ``Base 64 Encoding with URL and Filename Safe
+  # Alphabet'' in RFC 4648.
+  # The alphabet uses '-' instead of '+' and '_' instead of '/'.
+  def urlsafe_encode64(bin)
+    strict_encode64(bin).tr("+/", "-_")
+  end
+
+  # Returns the Base64-decoded version of +str+.
+  # This method complies with ``Base 64 Encoding with URL and Filename Safe
+  # Alphabet'' in RFC 4648.
+  # The alphabet uses '-' instead of '+' and '_' instead of '/'.
+  def urlsafe_decode64(str)
+    strict_decode64(str.tr("-_", "+/"))
+  end
+end