Merging upstream version 1.70.0+dfsg2.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 86 insertions, 0 deletions

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+# [RustCrypto]: Constant-Time Base64
+
+[![crate][crate-image]][crate-link]
+[![Docs][docs-image]][docs-link]
+[![Build Status][build-image]][build-link]
+![Apache2/MIT licensed][license-image]
+![Rust Version][rustc-image]
+[![Project Chat][chat-image]][chat-link]
+
+Pure Rust implementation of Base64 ([RFC 4648]).
+
+Implements multiple Base64 alphabets without data-dependent branches or lookup
+tables, thereby providing portable "best effort" constant-time operation.
+
+Supports `no_std` environments and avoids heap allocations in the core API
+(but also provides optional `alloc` support for convenience).
+
+[Documentation][docs-link]
+
+## About
+
+This crate implements several Base64 alphabets in constant-time for sidechannel
+resistance, aimed at purposes like encoding/decoding the "PEM" format used to
+store things like cryptographic private keys (i.e. in the [`pem-rfc7468`] crate).
+
+The paper [Util::Lookup: Exploiting key decoding in cryptographic libraries][Util::Lookup]
+demonstrates how the leakage from non-constant-time Base64 parsers can be used
+to practically extract RSA private keys from SGX enclaves.
+
+The padded variants require (`=`) padding. Unpadded variants expressly
+reject such padding.
+
+Whitespace is expressly disallowed, with the exception of the
+[`Decoder::new_wrapped`] and [`Encoder::new_wrapped`] modes which provide
+fixed-width line wrapping.
+
+## Supported Base64 variants
+
+- Standard Base64: `[A-Z]`, `[a-z]`, `[0-9]`, `+`, `/`
+- URL-safe Base64: `[A-Z]`, `[a-z]`, `[0-9]`, `-`, `_`
+- bcrypt Base64: `.`, `/`, `[A-Z]`, `[a-z]`, `[0-9]`
+- `crypt(3)` Base64: `.`, `-`, `[0-9]`, `[A-Z]`, `[a-z]`
+
+## Minimum Supported Rust Version
+
+This crate requires **Rust 1.56** at a minimum.
+
+We may change the MSRV in the future, but it will be accompanied by a minor
+version bump.
+
+## License
+
+Licensed under either of:
+
+ * [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0)
+ * [MIT license](http://opensource.org/licenses/MIT)
+
+at your option.
+
+### Contribution
+
+Unless you explicitly state otherwise, any contribution intentionally submitted
+for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
+dual licensed as above, without any additional terms or conditions.
+
+[//]: # (badges)
+
+[crate-image]: https://buildstats.info/crate/base64ct
+[crate-link]: https://crates.io/crates/base64ct
+[docs-image]: https://docs.rs/base64ct/badge.svg
+[docs-link]: https://docs.rs/base64ct/
+[build-image]: https://github.com/RustCrypto/formats/actions/workflows/base64ct.yml/badge.svg
+[build-link]: https://github.com/RustCrypto/formats/actions/workflows/base64ct.yml
+[license-image]: https://img.shields.io/badge/license-Apache2.0/MIT-blue.svg
+[rustc-image]: https://img.shields.io/badge/rustc-1.56+-blue.svg
+[chat-image]: https://img.shields.io/badge/zulip-join_chat-blue.svg
+[chat-link]: https://rustcrypto.zulipchat.com/#narrow/stream/300570-formats
+
+[//]: # (links)
+
+[RustCrypto]: https://github.com/rustcrypto
+[RFC 4648]: https://tools.ietf.org/html/rfc4648
+[`pem-rfc7468`]: https://github.com/RustCrypto/formats/tree/master/pem-rfc7468
+[Util::Lookup]: https://arxiv.org/pdf/2108.04600.pdf
+[`Decoder::new_wrapped`]: https://docs.rs/base64ct/latest/base64ct/struct.Decoder.html#method.new_wrapped
+[`Encoder::new_wrapped`]: https://docs.rs/base64ct/latest/base64ct/struct.Encoder.html#method.new_wrapped