diff options
| -rw-r--r-- | .cargo_vcs_info.json | 6 | ||||
| -rw-r--r-- | CHANGELOG.md | 44 | ||||
| -rw-r--r-- | Cargo.toml | 45 | ||||
| -rw-r--r-- | Cargo.toml.orig | 22 | ||||
| -rw-r--r-- | LICENSE-APACHE | 201 | ||||
| -rw-r--r-- | LICENSE-MIT | 25 | ||||
| -rw-r--r-- | src/lib.rs | 411 |
7 files changed, 754 insertions, 0 deletions
diff --git a/.cargo_vcs_info.json b/.cargo_vcs_info.json new file mode 100644 index 0000000..7d54855 --- /dev/null +++ b/.cargo_vcs_info.json @@ -0,0 +1,6 @@ +{ + "git": { + "sha1": "c1e32c58ca814c0b6265725002f4d853c3272bef" + }, + "path_in_vcs": "block-padding" +}
\ No newline at end of file diff --git a/CHANGELOG.md b/CHANGELOG.md new file mode 100644 index 0000000..8afef8b --- /dev/null +++ b/CHANGELOG.md @@ -0,0 +1,44 @@ +# Changelog +All notable changes to this project will be documented in this file. + +The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/), +and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html). + +## 0.3.3 (2023-04-02) +### Added +- `RawPadding` trait for padding blocks of arbitrary size ([#870]) + +[#870]: https://github.com/RustCrypto/utils/pull/870 + +## 0.3.2 (2022-03-10) +### Fixed +- Potential unsoundness for incorrect `Padding` implementations ([#748]) + +[#748]: https://github.com/RustCrypto/utils/pull/748 + +## 0.3.1 (2022-02-10) [YANKED] +### Fixed +- Fix doc build on docs.rs by optionally enabling the `doc_cfg` feature ([#733]) + +[#733]: https://github.com/RustCrypto/utils/pull/733 + +## 0.3.0 (2022-02-10) [YANKED] +### Added +- `Iso10126` padding algorithm ([#643]) +- `PadType` enum, `Padding::TYPE` associated constant, and `Padding::unpad_blocks` method ([#675]) + +### Changed +- The `Padding` trait methods now work with blocks instead of byte slices. ([#113]) +- Bump MSRV to 1.56 and edition to 2021 ([#675]) + +[#113]: https://github.com/RustCrypto/utils/pull/113 +[#643]: https://github.com/RustCrypto/utils/pull/643 +[#675]: https://github.com/RustCrypto/utils/pull/675 + +## 0.2.1 (2020-08-14) +### Added +- `Copy`, `Clone`, and `Debug` trait implementations for padding types. ([#78]) + +[#78]: https://github.com/RustCrypto/utils/pull/78 + +## 0.2.0 (2020-07-10) diff --git a/Cargo.toml b/Cargo.toml new file mode 100644 index 0000000..757231e --- /dev/null +++ b/Cargo.toml @@ -0,0 +1,45 @@ +# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO +# +# When uploading crates to the registry Cargo will automatically +# "normalize" Cargo.toml files for maximal compatibility +# with all versions of Cargo and also rewrite `path` dependencies +# to registry (e.g., crates.io) dependencies. +# +# If you are reading this file be aware that the original Cargo.toml +# will likely look very different (and much more reasonable). +# See Cargo.toml.orig for the original contents. + +[package] +edition = "2021" +rust-version = "1.56" +name = "block-padding" +version = "0.3.3" +authors = ["RustCrypto Developers"] +description = "Padding and unpadding of messages divided into blocks." +documentation = "https://docs.rs/block-padding" +keywords = [ + "padding", + "pkcs7", + "ansix923", + "iso7816", +] +categories = [ + "cryptography", + "no-std", +] +license = "MIT OR Apache-2.0" +repository = "https://github.com/RustCrypto/utils" +resolver = "1" + +[package.metadata.docs.rs] +all-features = true +rustdoc-args = [ + "--cfg", + "docsrs", +] + +[dependencies.generic-array] +version = "0.14" + +[features] +std = [] diff --git a/Cargo.toml.orig b/Cargo.toml.orig new file mode 100644 index 0000000..6a04971 --- /dev/null +++ b/Cargo.toml.orig @@ -0,0 +1,22 @@ +[package] +name = "block-padding" +version = "0.3.3" +description = "Padding and unpadding of messages divided into blocks." +authors = ["RustCrypto Developers"] +license = "MIT OR Apache-2.0" +edition = "2021" +rust-version = "1.56" +documentation = "https://docs.rs/block-padding" +repository = "https://github.com/RustCrypto/utils" +keywords = ["padding", "pkcs7", "ansix923", "iso7816"] +categories = ["cryptography", "no-std"] + +[dependencies] +generic-array = "0.14" + +[features] +std = [] + +[package.metadata.docs.rs] +all-features = true +rustdoc-args = ["--cfg", "docsrs"] diff --git a/LICENSE-APACHE b/LICENSE-APACHE new file mode 100644 index 0000000..78173fa --- /dev/null +++ b/LICENSE-APACHE @@ -0,0 +1,201 @@ + Apache License + Version 2.0, January 2004 + http://www.apache.org/licenses/ + +TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION + +1. Definitions. + + "License" shall mean the terms and conditions for use, reproduction, + and distribution as defined by Sections 1 through 9 of this document. + + "Licensor" shall mean the copyright owner or entity authorized by + the copyright owner that is granting the License. + + "Legal Entity" shall mean the union of the acting entity and all + other entities that control, are controlled by, or are under common + control with that entity. For the purposes of this definition, + "control" means (i) the power, direct or indirect, to cause the + direction or management of such entity, whether by contract or + otherwise, or (ii) ownership of fifty percent (50%) or more of the + outstanding shares, or (iii) beneficial ownership of such entity. + + "You" (or "Your") shall mean an individual or Legal Entity + exercising permissions granted by this License. + + "Source" form shall mean the preferred form for making modifications, + including but not limited to software source code, documentation + source, and configuration files. + + "Object" form shall mean any form resulting from mechanical + transformation or translation of a Source form, including but + not limited to compiled object code, generated documentation, + and conversions to other media types. + + "Work" shall mean the work of authorship, whether in Source or + Object form, made available under the License, as indicated by a + copyright notice that is included in or attached to the work + (an example is provided in the Appendix below). + + "Derivative Works" shall mean any work, whether in Source or Object + form, that is based on (or derived from) the Work and for which the + editorial revisions, annotations, elaborations, or other modifications + represent, as a whole, an original work of authorship. For the purposes + of this License, Derivative Works shall not include works that remain + separable from, or merely link (or bind by name) to the interfaces of, + the Work and Derivative Works thereof. + + "Contribution" shall mean any work of authorship, including + the original version of the Work and any modifications or additions + to that Work or Derivative Works thereof, that is intentionally + submitted to Licensor for inclusion in the Work by the copyright owner + or by an individual or Legal Entity authorized to submit on behalf of + the copyright owner. For the purposes of this definition, "submitted" + means any form of electronic, verbal, or written communication sent + to the Licensor or its representatives, including but not limited to + communication on electronic mailing lists, source code control systems, + and issue tracking systems that are managed by, or on behalf of, the + Licensor for the purpose of discussing and improving the Work, but + excluding communication that is conspicuously marked or otherwise + designated in writing by the copyright owner as "Not a Contribution." + + "Contributor" shall mean Licensor and any individual or Legal Entity + on behalf of whom a Contribution has been received by Licensor and + subsequently incorporated within the Work. + +2. Grant of Copyright License. Subject to the terms and conditions of + this License, each Contributor hereby grants to You a perpetual, + worldwide, non-exclusive, no-charge, royalty-free, irrevocable + copyright license to reproduce, prepare Derivative Works of, + publicly display, publicly perform, sublicense, and distribute the + Work and such Derivative Works in Source or Object form. + +3. Grant of Patent License. Subject to the terms and conditions of + this License, each Contributor hereby grants to You a perpetual, + worldwide, non-exclusive, no-charge, royalty-free, irrevocable + (except as stated in this section) patent license to make, have made, + use, offer to sell, sell, import, and otherwise transfer the Work, + where such license applies only to those patent claims licensable + by such Contributor that are necessarily infringed by their + Contribution(s) alone or by combination of their Contribution(s) + with the Work to which such Contribution(s) was submitted. If You + institute patent litigation against any entity (including a + cross-claim or counterclaim in a lawsuit) alleging that the Work + or a Contribution incorporated within the Work constitutes direct + or contributory patent infringement, then any patent licenses + granted to You under this License for that Work shall terminate + as of the date such litigation is filed. + +4. Redistribution. You may reproduce and distribute copies of the + Work or Derivative Works thereof in any medium, with or without + modifications, and in Source or Object form, provided that You + meet the following conditions: + + (a) You must give any other recipients of the Work or + Derivative Works a copy of this License; and + + (b) You must cause any modified files to carry prominent notices + stating that You changed the files; and + + (c) You must retain, in the Source form of any Derivative Works + that You distribute, all copyright, patent, trademark, and + attribution notices from the Source form of the Work, + excluding those notices that do not pertain to any part of + the Derivative Works; and + + (d) If the Work includes a "NOTICE" text file as part of its + distribution, then any Derivative Works that You distribute must + include a readable copy of the attribution notices contained + within such NOTICE file, excluding those notices that do not + pertain to any part of the Derivative Works, in at least one + of the following places: within a NOTICE text file distributed + as part of the Derivative Works; within the Source form or + documentation, if provided along with the Derivative Works; or, + within a display generated by the Derivative Works, if and + wherever such third-party notices normally appear. The contents + of the NOTICE file are for informational purposes only and + do not modify the License. You may add Your own attribution + notices within Derivative Works that You distribute, alongside + or as an addendum to the NOTICE text from the Work, provided + that such additional attribution notices cannot be construed + as modifying the License. + + You may add Your own copyright statement to Your modifications and + may provide additional or different license terms and conditions + for use, reproduction, or distribution of Your modifications, or + for any such Derivative Works as a whole, provided Your use, + reproduction, and distribution of the Work otherwise complies with + the conditions stated in this License. + +5. Submission of Contributions. Unless You explicitly state otherwise, + any Contribution intentionally submitted for inclusion in the Work + by You to the Licensor shall be under the terms and conditions of + this License, without any additional terms or conditions. + Notwithstanding the above, nothing herein shall supersede or modify + the terms of any separate license agreement you may have executed + with Licensor regarding such Contributions. + +6. Trademarks. This License does not grant permission to use the trade + names, trademarks, service marks, or product names of the Licensor, + except as required for reasonable and customary use in describing the + origin of the Work and reproducing the content of the NOTICE file. + +7. Disclaimer of Warranty. Unless required by applicable law or + agreed to in writing, Licensor provides the Work (and each + Contributor provides its Contributions) on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or + implied, including, without limitation, any warranties or conditions + of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A + PARTICULAR PURPOSE. You are solely responsible for determining the + appropriateness of using or redistributing the Work and assume any + risks associated with Your exercise of permissions under this License. + +8. Limitation of Liability. In no event and under no legal theory, + whether in tort (including negligence), contract, or otherwise, + unless required by applicable law (such as deliberate and grossly + negligent acts) or agreed to in writing, shall any Contributor be + liable to You for damages, including any direct, indirect, special, + incidental, or consequential damages of any character arising as a + result of this License or out of the use or inability to use the + Work (including but not limited to damages for loss of goodwill, + work stoppage, computer failure or malfunction, or any and all + other commercial damages or losses), even if such Contributor + has been advised of the possibility of such damages. + +9. Accepting Warranty or Additional Liability. While redistributing + the Work or Derivative Works thereof, You may choose to offer, + and charge a fee for, acceptance of support, warranty, indemnity, + or other liability obligations and/or rights consistent with this + License. However, in accepting such obligations, You may act only + on Your own behalf and on Your sole responsibility, not on behalf + of any other Contributor, and only if You agree to indemnify, + defend, and hold each Contributor harmless for any liability + incurred by, or claims asserted against, such Contributor by reason + of your accepting any such warranty or additional liability. + +END OF TERMS AND CONDITIONS + +APPENDIX: How to apply the Apache License to your work. + + To apply the Apache License to your work, attach the following + boilerplate notice, with the fields enclosed by brackets "[]" + replaced with your own identifying information. (Don't include + the brackets!) The text should be enclosed in the appropriate + comment syntax for the file format. We also recommend that a + file or class name and description of purpose be included on the + same "printed page" as the copyright notice for easier + identification within third-party archives. + +Copyright [yyyy] [name of copyright owner] + +Licensed under the Apache License, Version 2.0 (the "License"); +you may not use this file except in compliance with the License. +You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + +Unless required by applicable law or agreed to in writing, software +distributed under the License is distributed on an "AS IS" BASIS, +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +See the License for the specific language governing permissions and +limitations under the License. diff --git a/LICENSE-MIT b/LICENSE-MIT new file mode 100644 index 0000000..502cee6 --- /dev/null +++ b/LICENSE-MIT @@ -0,0 +1,25 @@ +Copyright (c) 2018-2019 The RustCrypto Project Developers + +Permission is hereby granted, free of charge, to any +person obtaining a copy of this software and associated +documentation files (the "Software"), to deal in the +Software without restriction, including without +limitation the rights to use, copy, modify, merge, +publish, distribute, sublicense, and/or sell copies of +the Software, and to permit persons to whom the Software +is furnished to do so, subject to the following +conditions: + +The above copyright notice and this permission notice +shall be included in all copies or substantial portions +of the Software. + +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF +ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED +TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A +PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT +SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY +CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION +OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR +IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER +DEALINGS IN THE SOFTWARE. diff --git a/src/lib.rs b/src/lib.rs new file mode 100644 index 0000000..be950cc --- /dev/null +++ b/src/lib.rs @@ -0,0 +1,411 @@ +//! Padding and unpadding of messages divided into blocks. +//! +//! This crate provides `Padding` trait which provides padding and unpadding +//! operations. Additionally several common padding schemes are available out +//! of the box. +#![no_std] +#![doc( + html_logo_url = "https://raw.githubusercontent.com/RustCrypto/media/6ee8e381/logo.svg", + html_favicon_url = "https://raw.githubusercontent.com/RustCrypto/media/6ee8e381/logo.svg" +)] +#![cfg_attr(docsrs, feature(doc_cfg))] +#![warn(missing_docs, rust_2018_idioms)] + +#[cfg(feature = "std")] +extern crate std; + +use core::fmt; +pub use generic_array; +use generic_array::{ArrayLength, GenericArray}; + +/// Padding types +#[derive(Copy, Clone, Debug, Eq, PartialEq)] +pub enum PadType { + /// Reversible padding + Reversible, + /// Ambiguous padding + Ambiguous, + /// No padding, message must be multiple of block size + NoPadding, +} + +/// Trait for padding messages divided into blocks of arbitrary size +pub trait RawPadding { + /// Padding type + const TYPE: PadType; + + /// Pads `block` filled with data up to `pos` (i.e length of a message + /// stored in the block is equal to `pos`). + /// + /// # Panics + /// If `pos` is bigger than `block.len()`. Most padding algorithms also + /// panic if they are equal. + fn raw_pad(block: &mut [u8], pos: usize); + + /// Unpad data in the `block`. + /// + /// Returns `Err(UnpadError)` if the block contains malformed padding. + fn raw_unpad(block: &[u8]) -> Result<&[u8], UnpadError>; +} + +/// Block size. +pub type Block<B> = GenericArray<u8, B>; + +/// Trait for padding messages divided into blocks +pub trait Padding<BlockSize: ArrayLength<u8>> { + /// Padding type + const TYPE: PadType; + + /// Pads `block` filled with data up to `pos` (i.e length of a message + /// stored in the block is equal to `pos`). + /// + /// # Panics + /// If `pos` is bigger than `BlockSize`. Most padding algorithms also + /// panic if they are equal. + fn pad(block: &mut Block<BlockSize>, pos: usize); + + /// Unpad data in the `block`. + /// + /// Returns `Err(UnpadError)` if the block contains malformed padding. + fn unpad(block: &Block<BlockSize>) -> Result<&[u8], UnpadError>; + + /// Unpad data in the `blocks`. + /// + /// Returns `Err(UnpadError)` if the block contains malformed padding. + fn unpad_blocks(blocks: &[Block<BlockSize>]) -> Result<&[u8], UnpadError> { + let bs = BlockSize::USIZE; + let res_len = match (blocks.last(), Self::TYPE) { + (_, PadType::NoPadding) => bs * blocks.len(), + (Some(last_block), _) => { + let n = Self::unpad(last_block)?.len(); + assert!(n <= bs); + n + bs * (blocks.len() - 1) + } + (None, PadType::Ambiguous) => 0, + (None, PadType::Reversible) => return Err(UnpadError), + }; + // SAFETY: `res_len` is always smaller or equal to `bs * blocks.len()` + Ok(unsafe { + let p = blocks.as_ptr() as *const u8; + core::slice::from_raw_parts(p, res_len) + }) + } +} + +impl<T, B: ArrayLength<u8>> Padding<B> for T +where + T: RawPadding, +{ + const TYPE: PadType = T::TYPE; + + #[inline] + fn pad(block: &mut Block<B>, pos: usize) { + T::raw_pad(block.as_mut_slice(), pos); + } + + #[inline] + fn unpad(block: &Block<B>) -> Result<&[u8], UnpadError> { + T::raw_unpad(block.as_slice()) + } +} + +/// Pad block with zeros. +/// +/// ``` +/// use block_padding::{ZeroPadding, Padding}; +/// use generic_array::{GenericArray, typenum::U8}; +/// +/// let msg = b"test"; +/// let pos = msg.len(); +/// let mut block: GenericArray::<u8, U8> = [0xff; 8].into(); +/// block[..pos].copy_from_slice(msg); +/// ZeroPadding::pad(&mut block, pos); +/// assert_eq!(&block[..], b"test\x00\x00\x00\x00"); +/// let res = ZeroPadding::unpad(&mut block).unwrap(); +/// assert_eq!(res, msg); +/// ``` +/// +/// Note that zero padding is not reversible for messages which end +/// with one or more zero bytes. +#[derive(Clone, Copy, Debug)] +pub struct ZeroPadding; + +impl RawPadding for ZeroPadding { + const TYPE: PadType = PadType::Ambiguous; + + #[inline] + fn raw_pad(block: &mut [u8], pos: usize) { + if pos > block.len() { + panic!("`pos` is bigger than block size"); + } + for b in &mut block[pos..] { + *b = 0; + } + } + + #[inline] + fn raw_unpad(block: &[u8]) -> Result<&[u8], UnpadError> { + for i in (0..block.len()).rev() { + if block[i] != 0 { + return Ok(&block[..i + 1]); + } + } + Ok(&block[..0]) + } +} + +/// Pad block with bytes with value equal to the number of bytes added. +/// +/// PKCS#7 described in the [RFC 5652](https://tools.ietf.org/html/rfc5652#section-6.3). +/// +/// ``` +/// use block_padding::{Pkcs7, Padding}; +/// use generic_array::{GenericArray, typenum::U8}; +/// +/// let msg = b"test"; +/// let pos = msg.len(); +/// let mut block: GenericArray::<u8, U8> = [0xff; 8].into(); +/// block[..pos].copy_from_slice(msg); +/// Pkcs7::pad(&mut block, pos); +/// assert_eq!(&block[..], b"test\x04\x04\x04\x04"); +/// let res = Pkcs7::unpad(&block).unwrap(); +/// assert_eq!(res, msg); +/// ``` +#[derive(Clone, Copy, Debug)] +pub struct Pkcs7; + +impl Pkcs7 { + #[inline] + fn unpad(block: &[u8], strict: bool) -> Result<&[u8], UnpadError> { + // TODO: use bounds to check it at compile time + if block.len() > 255 { + panic!("block size is too big for PKCS#7"); + } + let bs = block.len(); + let n = block[bs - 1]; + if n == 0 || n as usize > bs { + return Err(UnpadError); + } + let s = bs - n as usize; + if strict && block[s..bs - 1].iter().any(|&v| v != n) { + return Err(UnpadError); + } + Ok(&block[..s]) + } +} + +impl RawPadding for Pkcs7 { + const TYPE: PadType = PadType::Reversible; + + #[inline] + fn raw_pad(block: &mut [u8], pos: usize) { + // TODO: use bounds to check it at compile time for Padding<B> + if block.len() > 255 { + panic!("block size is too big for PKCS#7"); + } + if pos >= block.len() { + panic!("`pos` is bigger or equal to block size"); + } + let n = (block.len() - pos) as u8; + for b in &mut block[pos..] { + *b = n; + } + } + + #[inline] + fn raw_unpad(block: &[u8]) -> Result<&[u8], UnpadError> { + Pkcs7::unpad(block, true) + } +} + +/// Pad block with arbitrary bytes ending with value equal to the number of bytes added. +/// +/// A variation of PKCS#7 that is less strict when decoding. +/// +/// ``` +/// use block_padding::{Iso10126, Padding}; +/// use generic_array::{GenericArray, typenum::U8}; +/// +/// let msg = b"test"; +/// let pos = msg.len(); +/// let mut block: GenericArray::<u8, U8> = [0xff; 8].into(); +/// block[..pos].copy_from_slice(msg); +/// Iso10126::pad(&mut block, pos); +/// assert_eq!(&block[..], b"test\x04\x04\x04\x04"); +/// let res = Iso10126::unpad(&block).unwrap(); +/// assert_eq!(res, msg); +/// ``` +#[derive(Clone, Copy, Debug)] +pub struct Iso10126; + +impl RawPadding for Iso10126 { + const TYPE: PadType = PadType::Reversible; + + #[inline] + fn raw_pad(block: &mut [u8], pos: usize) { + // Instead of generating random bytes as specified by Iso10126 we + // simply use Pkcs7 padding. + Pkcs7::raw_pad(block, pos) + } + + #[inline] + fn raw_unpad(block: &[u8]) -> Result<&[u8], UnpadError> { + Pkcs7::unpad(block, false) + } +} + +/// Pad block with zeros except the last byte which will be set to the number +/// bytes. +/// +/// ``` +/// use block_padding::{AnsiX923, Padding}; +/// use generic_array::{GenericArray, typenum::U8}; +/// +/// let msg = b"test"; +/// let pos = msg.len(); +/// let mut block: GenericArray::<u8, U8> = [0xff; 8].into(); +/// block[..pos].copy_from_slice(msg); +/// AnsiX923::pad(&mut block, pos); +/// assert_eq!(&block[..], b"test\x00\x00\x00\x04"); +/// let res = AnsiX923::unpad(&block).unwrap(); +/// assert_eq!(res, msg); +/// ``` +#[derive(Clone, Copy, Debug)] +pub struct AnsiX923; + +impl RawPadding for AnsiX923 { + const TYPE: PadType = PadType::Reversible; + + #[inline] + fn raw_pad(block: &mut [u8], pos: usize) { + // TODO: use bounds to check it at compile time + if block.len() > 255 { + panic!("block size is too big for PKCS#7"); + } + if pos >= block.len() { + panic!("`pos` is bigger or equal to block size"); + } + let bs = block.len(); + for b in &mut block[pos..bs - 1] { + *b = 0; + } + block[bs - 1] = (bs - pos) as u8; + } + + #[inline] + fn raw_unpad(block: &[u8]) -> Result<&[u8], UnpadError> { + // TODO: use bounds to check it at compile time + if block.len() > 255 { + panic!("block size is too big for PKCS#7"); + } + let bs = block.len(); + let n = block[bs - 1] as usize; + if n == 0 || n > bs { + return Err(UnpadError); + } + let s = bs - n; + if block[s..bs - 1].iter().any(|&v| v != 0) { + return Err(UnpadError); + } + Ok(&block[..s]) + } +} + +/// Pad block with byte sequence `\x80 00...00 00`. +/// +/// ``` +/// use block_padding::{Iso7816, Padding}; +/// use generic_array::{GenericArray, typenum::U8}; +/// +/// let msg = b"test"; +/// let pos = msg.len(); +/// let mut block: GenericArray::<u8, U8> = [0xff; 8].into(); +/// block[..pos].copy_from_slice(msg); +/// Iso7816::pad(&mut block, pos); +/// assert_eq!(&block[..], b"test\x80\x00\x00\x00"); +/// let res = Iso7816::unpad(&block).unwrap(); +/// assert_eq!(res, msg); +/// ``` +#[derive(Clone, Copy, Debug)] +pub struct Iso7816; + +impl RawPadding for Iso7816 { + const TYPE: PadType = PadType::Reversible; + + #[inline] + fn raw_pad(block: &mut [u8], pos: usize) { + if pos >= block.len() { + panic!("`pos` is bigger or equal to block size"); + } + block[pos] = 0x80; + for b in &mut block[pos + 1..] { + *b = 0; + } + } + + #[inline] + fn raw_unpad(block: &[u8]) -> Result<&[u8], UnpadError> { + for i in (0..block.len()).rev() { + match block[i] { + 0x80 => return Ok(&block[..i]), + 0x00 => continue, + _ => return Err(UnpadError), + } + } + Err(UnpadError) + } +} + +/// Don't pad the data. Useful for key wrapping. +/// +/// ``` +/// use block_padding::{NoPadding, Padding}; +/// use generic_array::{GenericArray, typenum::U8}; +/// +/// let msg = b"test"; +/// let pos = msg.len(); +/// let mut block: GenericArray::<u8, U8> = [0xff; 8].into(); +/// block[..pos].copy_from_slice(msg); +/// NoPadding::pad(&mut block, pos); +/// assert_eq!(&block[..], b"test\xff\xff\xff\xff"); +/// let res = NoPadding::unpad(&block).unwrap(); +/// assert_eq!(res, b"test\xff\xff\xff\xff"); +/// ``` +/// +/// Note that even though the passed length of the message is equal to 4, +/// the size of unpadded message is equal to the block size of 8 bytes. +/// Also padded message contains "garbage" bytes stored in the block buffer. +/// Thus `NoPadding` generally should not be used with data length of which +/// is not multiple of block size. +#[derive(Clone, Copy, Debug)] +pub struct NoPadding; + +impl RawPadding for NoPadding { + const TYPE: PadType = PadType::NoPadding; + + #[inline] + fn raw_pad(block: &mut [u8], pos: usize) { + if pos > block.len() { + panic!("`pos` is bigger than block size"); + } + } + + #[inline] + fn raw_unpad(block: &[u8]) -> Result<&[u8], UnpadError> { + Ok(block) + } +} + +/// Failed unpadding operation error. +#[derive(Clone, Copy, Debug)] +pub struct UnpadError; + +impl fmt::Display for UnpadError { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> { + f.write_str("Unpad Error") + } +} + +#[cfg(feature = "std")] +#[cfg_attr(docsrs, doc(cfg(feature = "std")))] +impl std::error::Error for UnpadError {} |