Throw an error on invalid base64 strings #28
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RFC 4648 states that "implementations MUST reject the encoded data if it contains characters outside the base alphabet when interpreting base-encoded data, unless the specification referring to this document explicitly states otherwise." RFC 7515 specifies base64url encoding as "base64 encoding using the URL- and filename-safe character set defined in Section 5 of RFC 4648, with all trailing '=' characters omitted and without the inclusion of any line breaks, whitespace, or _other additional characters_." Python's base64.urlsafe_b64decode() does not validate its argument, ignoring unknown characters instead. It also accepts "+" and "/" in addition to "-" and "_" [1]. base64.b64decode()'s validate argument makes it validate its input, but it still accepts non-urlsafe base64 encoding as well [1]. This commit therefore changes util.urlsafe_b64decode() to explicitly check for "+" and "/" in input before passing it to base64.b64decode() with its validate argument set to True. [1]: python/cpython#125346
viccie30
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## main #28 +/- ##
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Coverage 100.00% 100.00%
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Files 44 44
Lines 2564 2567 +3
Branches 364 303 -61
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RFC 4648 states that "implementations MUST reject the encoded data if it contains characters outside the base alphabet when interpreting base-encoded data, unless the specification referring to this document explicitly states otherwise."
RFC 7515 specifies base64url encoding as "base64 encoding using the URL- and filename-safe character set defined in Section 5 of RFC 4648, with all trailing '=' characters omitted and without the inclusion of any line breaks, whitespace, or other additional characters."
Python's
base64.urlsafe_b64decode()does not validate its argument, ignoring unknown characters instead. It also accepts "+" and "/" in addition to "-" and "_".base64.b64decode()'s validate argument makes it validate its input, but it still accepts non-urlsafe base64 encoding as well.This commit therefore changes
util.urlsafe_b64decode()to explicitly check for "+" and "/" in input before passing it tobase64.b64decode()with its validate argument set toTrue.