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Base64

The Base64 module provides for the encoding (#encode64) and decoding (#decode64) of binary data using a Base64 representation.

The following particular features are also provided:

  • encode into lines of a given length (#b64encode)

  • decode the special format specified in RFC2047 for the representation of email headers (decode_b)

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. It is specified in RFC 2045 (www.faqs.org/rfcs/rfc2045.html).

Public Instance Methods

b64encode(bin, len = 60) click to toggle source

Prints the Base64 encoded version of bin (a String) in lines of len (default 60) characters.

require 'base64'
data = "Now is the time for all good coders\nto learn Ruby" 
Base64.b64encode(data)

Generates:

Tm93IGlzIHRoZSB0aW1lIGZvciBhbGwgZ29vZCBjb2RlcnMKdG8gbGVhcm4g
UnVieQ==
 
               # File base64.rb, line 112
def b64encode(bin, len = 60)
  encode64(bin).scan(/.{1,#{len}}/) do
    print $&, "\n"
  end
end
decode64(str) click to toggle source

Returns the Base64-decoded version of str.

require 'base64'
str = 'VGhpcyBpcyBsaW5lIG9uZQpUaGlzIG' +
      'lzIGxpbmUgdHdvClRoaXMgaXMgbGlu' +
      'ZSB0aHJlZQpBbmQgc28gb24uLi4K'
puts Base64.decode64(str)

Generates:

This is line one
This is line two
This is line three
And so on...
 
               # File base64.rb, line 58
def decode64(str)
  str.unpack("m")[0]
end
decode_b(str) click to toggle source

Decodes text formatted using a subset of RFC2047 (the one used for mime-encoding mail headers).

Only supports an encoding type of 'b' (base 64), and only supports the character sets ISO-2022-JP and SHIFT_JIS (so the only two encoded word sequences recognized are =?ISO-2022-JP?B?...= and =?SHIFT_JIS?B?...=). Recognition of these sequences is case insensitive.

 
               # File base64.rb, line 72
def decode_b(str)
  str.gsub!(/=\?ISO-2022-JP\?B\?([!->@-~]+)\?=/i) {
    decode64($1)
  }
  str = Kconv::toeuc(str)
  str.gsub!(/=\?SHIFT_JIS\?B\?([!->@-~]+)\?=/i) {
    decode64($1)
  }
  str = Kconv::toeuc(str)
  str.gsub!(/\n/, ' ') 
  str.gsub!(/\0/, '')
  str
end
encode64(bin) click to toggle source

Returns the Base64-encoded version of str.

require 'base64'
Base64.b64encode("Now is the time for all good coders\nto learn Ruby")

Generates:

Tm93IGlzIHRoZSB0aW1lIGZvciBhbGwgZ29vZCBjb2RlcnMKdG8gbGVhcm4g
UnVieQ==
 
               # File base64.rb, line 96
def encode64(bin)
  [bin].pack("m")
end