René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Add the ignorechars parameter in the Base64 decoder","articleBody":"# Feature or enhancement\n\nEarlier standards for Base64 ([RFC 1421](https://datatracker.ietf.org/doc/html/rfc1421), [RFC 1521](https://datatracker.ietf.org/doc/html/rfc1521)) on which the `base64` and `binascii` 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](https://datatracker.ietf.org/doc/html/rfc4648)) 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\" -- either _all_ 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.\n\n`a85decode()` has parameter `ignorechars` which could also be used to control Base64 decoding.\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-144009\n* gh-144024\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/serhiy-storchaka","@type":"Person","name":"serhiy-storchaka"},"datePublished":"2026-01-18T14:41:17.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":2},"url":"https://github.com/144001/cpython/issues/144001"}