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108 lines
3.3 KiB
Ruby
108 lines
3.3 KiB
Ruby
# frozen_string_literal: true
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#
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# = base64.rb: methods for base64-encoding and -decoding strings
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#
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# The Base64 module provides for the encoding (#encode64, #strict_encode64,
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# #urlsafe_encode64) and decoding (#decode64, #strict_decode64,
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# #urlsafe_decode64) of binary data using a Base64 representation.
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#
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# == Example
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#
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# A simple encoding and decoding.
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#
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# require "base64"
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#
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# enc = Base64.encode64('Send reinforcements')
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# # -> "U2VuZCByZWluZm9yY2VtZW50cw==\n"
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# plain = Base64.decode64(enc)
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# # -> "Send reinforcements"
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#
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# The purpose of using base64 to encode data is that it translates any
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# binary data into purely printable characters.
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module Base64
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module_function
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# Returns the Base64-encoded version of +bin+.
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# This method complies with RFC 2045.
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# Line feeds are added to every 60 encoded characters.
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#
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# require 'base64'
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# Base64.encode64("Now is the time for all good coders\nto learn Ruby")
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#
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# <i>Generates:</i>
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#
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# Tm93IGlzIHRoZSB0aW1lIGZvciBhbGwgZ29vZCBjb2RlcnMKdG8gbGVhcm4g
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# UnVieQ==
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def encode64(bin)
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[bin].pack("m")
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end
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# Returns the Base64-decoded version of +str+.
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# This method complies with RFC 2045.
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# Characters outside the base alphabet are ignored.
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#
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# require 'base64'
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# str = 'VGhpcyBpcyBsaW5lIG9uZQpUaGlzIG' +
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# 'lzIGxpbmUgdHdvClRoaXMgaXMgbGlu' +
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# 'ZSB0aHJlZQpBbmQgc28gb24uLi4K'
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# puts Base64.decode64(str)
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#
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# <i>Generates:</i>
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#
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# This is line one
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# This is line two
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# This is line three
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# And so on...
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def decode64(str)
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str.unpack1("m")
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end
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# Returns the Base64-encoded version of +bin+.
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# This method complies with RFC 4648.
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# No line feeds are added.
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def strict_encode64(bin)
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[bin].pack("m0")
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end
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# Returns the Base64-decoded version of +str+.
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# This method complies with RFC 4648.
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# ArgumentError is raised if +str+ is incorrectly padded or contains
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# non-alphabet characters. Note that CR or LF are also rejected.
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def strict_decode64(str)
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str.unpack1("m0")
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end
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# Returns the Base64-encoded version of +bin+.
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# This method complies with ``Base 64 Encoding with URL and Filename Safe
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# Alphabet'' in RFC 4648.
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# The alphabet uses '-' instead of '+' and '_' instead of '/'.
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# Note that the result can still contain '='.
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# You can remove the padding by setting +padding+ as false.
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def urlsafe_encode64(bin, padding: true)
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str = strict_encode64(bin)
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str.tr!("+/", "-_")
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str.delete!("=") unless padding
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str
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end
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# Returns the Base64-decoded version of +str+.
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# This method complies with ``Base 64 Encoding with URL and Filename Safe
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# Alphabet'' in RFC 4648.
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# The alphabet uses '-' instead of '+' and '_' instead of '/'.
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#
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# The padding character is optional.
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# This method accepts both correctly-padded and unpadded input.
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# Note that it still rejects incorrectly-padded input.
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def urlsafe_decode64(str)
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# NOTE: RFC 4648 does say nothing about unpadded input, but says that
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# "the excess pad characters MAY also be ignored", so it is inferred that
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# unpadded input is also acceptable.
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str = str.tr("-_", "+/")
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if !str.end_with?("=") && str.length % 4 != 0
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str = str.ljust((str.length + 3) & ~3, "=")
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end
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strict_decode64(str)
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end
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end
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