Base64 provides utility methods for encoding and de-coding binary data using a base 64 representation. A base 64 representation of binary data consists entirely of printable US-ASCII characters. The Base64 module is included in Ruby 1.8, but has been removed in Ruby 1.9.

Methods
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E
Class Public methods
decode64(data)

Decodes a base 64 encoded string to its original representation. 

 ActiveSupport::Base64.decode64("T3JpZ2luYWwgdW5lbmNvZGVkIHN0cmluZw==")
 # => "Original unencoded string"

Source: show | on GitHub 

    # File activesupport/lib/active_support/base64.rb, line 28
28:       def self.decode64(data)
29:         data.unpack("m").first
30:       end
encode64(data)

Encodes a string to its base 64 representation. Each 60 characters of output is separated by a newline character. 

 ActiveSupport::Base64.encode64("Original unencoded string")
 # => "T3JpZ2luYWwgdW5lbmNvZGVkIHN0cmluZw==\n"

Source: show | on GitHub 

    # File activesupport/lib/active_support/base64.rb, line 20
20:       def self.encode64(data)
21:         [data].pack("m")
22:       end