[ruby-core:67644] [ruby-trunk - Feature #10740] Base64 urlsafe methods are not urlsafe

Issue #10740 has been updated by Yusuke Endoh.


Nobuyoshi Nakada wrote:
> Why does `urlsafe_decode64` use `strict_decode64`, but not just `unpack("m")`?

unpack("m") and Base64.decode64 are based on RFC 2045.  unpack("m0"), Base64.strict_decode64, and Base64.urlsafe_decode64 (base64url) are based on RFC 4648.

RFC 2045 allows characters outside the base alphabet, such as CR and LF, and RFC 4648 does not (by default).

-- 
Yusuke Endoh <[e-mail]>

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Feature #10740: Base64 urlsafe methods are not urlsafe
https://bugs.ruby-lang.org/issues/10740#change-51065

* Author: Scott Blum
* Status: Feedback
* Priority: Normal
* Assignee: Yusuke Endoh
----------------------------------------
Base64.urlsafe_decode64 is not to spec, because it currently REQUIRES appropriate trailing '=' characters.
Base64.urlsafe_encode64 produces trailing '=' characters.

'=' is not web safe, and is not recommended for base64url.  Some specs even disallow.

Suggested fix:

~~~
  # 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 '/'
  # and has no trailing pad characters.
  def urlsafe_encode64(bin)
    strict_encode64(bin).tr("+/", "-_").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 '/'.
  # Trailing pad characters are optional.
  def urlsafe_decode64(str)
    str = str.tr("-_", "+/")
    str = str.ljust((str.length + 3) & ~3, '=')
    strict_decode64(str)
  end
~~~


---Files--------------------------------
base64-urlsafe-encode64-search-result.txt (19.9 KB)
urlsafe_base64.patch (2.97 KB)


-- 
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