base64-ng-derive

Dependency-free derive helpers for fixed-size base64-ng byte newtypes.

This companion crate keeps the core base64-ng package free of proc-macro dependencies. It supports one deliberately narrow shape:

use base64_ng_derive::Base64Secret;

#[derive(Base64Secret)]
struct ApiKey([u8; 32]);

The generated impls provide:

• from_base64(&[u8]) and from_base64_str(&str) using base64_ng::ct::STANDARD.decode_slice_staged_clear_tail.
• encode_base64::<CAP>() using strict standard padded Base64.
• as_bytes(), as_mut_bytes(), and constant_time_eq(&Self).
• redacted Debug.
• drop-time cleanup through base64_ng::clear_bytes.

The macro intentionally does not support named structs, multiple fields, generic structs, or non-array storage. Use base64-ng-sanitization when you want integration with a dedicated clear-on-drop secret container.