Feature or enhancement

Earlier standards for Base64 (RFC 1421,RFC 1521) on which thebase64 andbinascii modules are based, specified that any non-alphabet characters should be ignored, and this is the default behavior of these modules. More modern standard (RFC 4648) considers this a vulnerability, and specify that they should be rejected until the upper lever document states otherwise. Thus,strict_mode/validate parameters were added. But they are "all-or-nothing" -- eitherall non-alphabet characters are rejected, or other errors are ignored. In some cases we need to ignore only the part of errors -- for example, ignore newlines and whitespaces, but not other invalid characters, or ignore padding errors.

a85decode() has parameterignorechars which could also be used to control Base64 decoding.

Linked PRs

• gh-144001: Add ignorechars parameter to Base64 decoder #144009
• gh-144001: Support ignorechars in binascii.a2b_base64() and base64.b64decode() #144024
• gh-144001: Support ignoring the invalid pad character in Base64 decoding #144306