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Diffstat (limited to 'vendor/block-padding/src/lib.rs')
| -rw-r--r-- | vendor/block-padding/src/lib.rs | 323 |
1 files changed, 323 insertions, 0 deletions
diff --git a/vendor/block-padding/src/lib.rs b/vendor/block-padding/src/lib.rs new file mode 100644 index 000000000..5c4c8c3b6 --- /dev/null +++ b/vendor/block-padding/src/lib.rs @@ -0,0 +1,323 @@ +//! 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/meta/master/logo_small.png")] +extern crate byte_tools; + +use byte_tools::{zero, set}; + +/// Error for indicating failed padding operation +#[derive(Clone, Copy, Debug)] +pub struct PadError; + +/// Error for indicating failed unpadding operation +#[derive(Clone, Copy, Debug)] +pub struct UnpadError; + +/// Trait for padding messages divided into blocks +pub trait Padding { + /// Pads `block` filled with data up to `pos`. + /// + /// `pos` should be inside of the block and block must not be full, i.e. + /// `pos < block.len()` must be true. Otherwise method will return + /// `PadError`. Some potentially irreversible padding schemes can allow + /// padding of the full block, in this case aforementioned condition is + /// relaxed to `pos <= block.len()`. + fn pad_block(block: &mut [u8], pos: usize) -> Result<(), PadError>; + + /// Pads message with length `pos` in the provided buffer. + /// + /// `&buf[..pos]` is perceived as the message, the buffer must contain + /// enough leftover space for padding: `block_size - (pos % block_size)` + /// extra bytes must be available. Otherwise method will return + /// `PadError`. + fn pad(buf: &mut [u8], pos: usize, block_size: usize) + -> Result<&mut [u8], PadError> + { + let bs = block_size * (pos / block_size); + if buf.len() < bs || buf.len() - bs < block_size { Err(PadError)? } + Self::pad_block(&mut buf[bs..bs+block_size], pos - bs)?; + Ok(&mut buf[..bs+block_size]) + } + + /// Unpad given `data` by truncating it according to the used padding. + /// In case of the malformed padding will return `UnpadError` + fn unpad(data: &[u8]) -> Result<&[u8], UnpadError>; +} + +/// Pad block with zeros. +/// +/// ``` +/// use block_padding::{ZeroPadding, Padding}; +/// +/// let msg = b"test"; +/// let n = msg.len(); +/// let mut buffer = [0xff; 16]; +/// buffer[..n].copy_from_slice(msg); +/// let padded_msg = ZeroPadding::pad(&mut buffer, n, 8).unwrap(); +/// assert_eq!(padded_msg, b"test\x00\x00\x00\x00"); +/// assert_eq!(ZeroPadding::unpad(&padded_msg).unwrap(), msg); +/// ``` +/// ``` +/// # use block_padding::{ZeroPadding, Padding}; +/// # let msg = b"test"; +/// # let n = msg.len(); +/// # let mut buffer = [0xff; 16]; +/// # buffer[..n].copy_from_slice(msg); +/// let padded_msg = ZeroPadding::pad(&mut buffer, n, 2).unwrap(); +/// assert_eq!(padded_msg, b"test"); +/// assert_eq!(ZeroPadding::unpad(&padded_msg).unwrap(), msg); +/// ``` +/// +/// Note that zero padding may not be reversible if the original message ends +/// with one or more zero bytes. +pub enum ZeroPadding{} + +impl Padding for ZeroPadding { + fn pad_block(block: &mut [u8], pos: usize) -> Result<(), PadError> { + if pos > block.len() { Err(PadError)? } + zero(&mut block[pos..]); + Ok(()) + } + + fn pad(buf: &mut [u8], pos: usize, block_size: usize) + -> Result<&mut [u8], PadError> + { + if pos % block_size == 0 { + Ok(&mut buf[..pos]) + } else { + let bs = block_size * (pos / block_size); + let be = bs + block_size; + if buf.len() < be { Err(PadError)? } + Self::pad_block(&mut buf[bs..be], pos - bs)?; + Ok(&mut buf[..be]) + } + } + + fn unpad(data: &[u8]) -> Result<&[u8], UnpadError> { + let mut n = data.len() - 1; + while n != 0 { + if data[n] != 0 { + break; + } + n -= 1; + } + Ok(&data[..n+1]) + } +} + +/// 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}; +/// +/// let msg = b"test"; +/// let n = msg.len(); +/// let mut buffer = [0xff; 8]; +/// buffer[..n].copy_from_slice(msg); +/// let padded_msg = Pkcs7::pad(&mut buffer, n, 8).unwrap(); +/// assert_eq!(padded_msg, b"test\x04\x04\x04\x04"); +/// assert_eq!(Pkcs7::unpad(&padded_msg).unwrap(), msg); +/// ``` +/// ``` +/// # use block_padding::{Pkcs7, Padding}; +/// # let msg = b"test"; +/// # let n = msg.len(); +/// # let mut buffer = [0xff; 8]; +/// # buffer[..n].copy_from_slice(msg); +/// let padded_msg = Pkcs7::pad(&mut buffer, n, 2).unwrap(); +/// assert_eq!(padded_msg, b"test\x02\x02"); +/// assert_eq!(Pkcs7::unpad(&padded_msg).unwrap(), msg); +/// ``` +/// ``` +/// # use block_padding::{Pkcs7, Padding}; +/// let mut buffer = [0xff; 5]; +/// assert!(Pkcs7::pad(&mut buffer, 4, 2).is_err()); +/// ``` +/// ``` +/// # use block_padding::{Pkcs7, Padding}; +/// # let buffer = [0xff; 16]; +/// assert!(Pkcs7::unpad(&buffer).is_err()); +/// ``` +/// +/// In addition to conditions stated in the `Padding` trait documentation, +/// `pad_block` will return `PadError` if `block.len() > 255`, and in case of +/// `pad` if `block_size > 255`. +pub enum Pkcs7{} + +impl Padding for Pkcs7 { + fn pad_block(block: &mut [u8], pos: usize) -> Result<(), PadError> { + if block.len() > 255 { Err(PadError)? } + if pos >= block.len() { Err(PadError)? } + let n = block.len() - pos; + set(&mut block[pos..], n as u8); + Ok(()) + } + + fn unpad(data: &[u8]) -> Result<&[u8], UnpadError> { + if data.is_empty() { Err(UnpadError)? } + let l = data.len(); + let n = data[l-1]; + if n == 0 || n as usize > l { Err(UnpadError)? } + for v in &data[l-n as usize..l-1] { + if *v != n { Err(UnpadError)? } + } + Ok(&data[..l - n as usize]) + } +} + +/// Pad block with zeros except the last byte which will be set to the number +/// bytes. +/// +/// ``` +/// use block_padding::{AnsiX923, Padding}; +/// +/// let msg = b"test"; +/// let n = msg.len(); +/// let mut buffer = [0xff; 16]; +/// buffer[..n].copy_from_slice(msg); +/// let padded_msg = AnsiX923::pad(&mut buffer, n, 8).unwrap(); +/// assert_eq!(padded_msg, b"test\x00\x00\x00\x04"); +/// assert_eq!(AnsiX923::unpad(&padded_msg).unwrap(), msg); +/// ``` +/// ``` +/// # use block_padding::{AnsiX923, Padding}; +/// # let msg = b"test"; +/// # let n = msg.len(); +/// # let mut buffer = [0xff; 16]; +/// # buffer[..n].copy_from_slice(msg); +/// let padded_msg = AnsiX923::pad(&mut buffer, n, 2).unwrap(); +/// assert_eq!(padded_msg, b"test\x00\x02"); +/// assert_eq!(AnsiX923::unpad(&padded_msg).unwrap(), msg); +/// ``` +/// ``` +/// # use block_padding::{AnsiX923, Padding}; +/// # let buffer = [0xff; 16]; +/// assert!(AnsiX923::unpad(&buffer).is_err()); +/// ``` +/// +/// In addition to conditions stated in the `Padding` trait documentation, +/// `pad_block` will return `PadError` if `block.len() > 255`, and in case of +/// `pad` if `block_size > 255`. +pub enum AnsiX923{} + +impl Padding for AnsiX923 { + fn pad_block(block: &mut [u8], pos: usize) -> Result<(), PadError>{ + if block.len() > 255 { Err(PadError)? } + if pos >= block.len() { Err(PadError)? } + let bs = block.len(); + zero(&mut block[pos..bs-1]); + block[bs-1] = (bs - pos) as u8; + Ok(()) + } + + fn unpad(data: &[u8]) -> Result<&[u8], UnpadError> { + if data.is_empty() { Err(UnpadError)? } + let l = data.len(); + let n = data[l-1] as usize; + if n == 0 || n > l { + return Err(UnpadError) + } + for v in &data[l-n..l-1] { + if *v != 0 { Err(UnpadError)? } + } + Ok(&data[..l-n]) + } +} + +/// Pad block with byte sequence `\x80 00...00 00`. +/// +/// ``` +/// use block_padding::{Iso7816, Padding}; +/// +/// let msg = b"test"; +/// let n = msg.len(); +/// let mut buffer = [0xff; 16]; +/// buffer[..n].copy_from_slice(msg); +/// let padded_msg = Iso7816::pad(&mut buffer, n, 8).unwrap(); +/// assert_eq!(padded_msg, b"test\x80\x00\x00\x00"); +/// assert_eq!(Iso7816::unpad(&padded_msg).unwrap(), msg); +/// ``` +/// ``` +/// # use block_padding::{Iso7816, Padding}; +/// # let msg = b"test"; +/// # let n = msg.len(); +/// # let mut buffer = [0xff; 16]; +/// # buffer[..n].copy_from_slice(msg); +/// let padded_msg = Iso7816::pad(&mut buffer, n, 2).unwrap(); +/// assert_eq!(padded_msg, b"test\x80\x00"); +/// assert_eq!(Iso7816::unpad(&padded_msg).unwrap(), msg); +/// ``` +pub enum Iso7816{} + +impl Padding for Iso7816 { + fn pad_block(block: &mut [u8], pos: usize) -> Result<(), PadError> { + if pos >= block.len() { Err(PadError)? } + block[pos] = 0x80; + zero(&mut block[pos+1..]); + Ok(()) + } + + fn unpad(data: &[u8]) -> Result<&[u8], UnpadError> { + if data.is_empty() { Err(UnpadError)? } + let mut n = data.len() - 1; + while n != 0 { + if data[n] != 0 { break; } + n -= 1; + } + if data[n] != 0x80 { Err(UnpadError)? } + Ok(&data[..n]) + } +} + +/// Don't pad the data. Useful for key wrapping. Padding will fail if the data cannot be +/// fitted into blocks without padding. +/// +/// ``` +/// use block_padding::{NoPadding, Padding}; +/// +/// let msg = b"test"; +/// let n = msg.len(); +/// let mut buffer = [0xff; 16]; +/// buffer[..n].copy_from_slice(msg); +/// let padded_msg = NoPadding::pad(&mut buffer, n, 4).unwrap(); +/// assert_eq!(padded_msg, b"test"); +/// assert_eq!(NoPadding::unpad(&padded_msg).unwrap(), msg); +/// ``` +/// ``` +/// # use block_padding::{NoPadding, Padding}; +/// # let msg = b"test"; +/// # let n = msg.len(); +/// # let mut buffer = [0xff; 16]; +/// # buffer[..n].copy_from_slice(msg); +/// let padded_msg = NoPadding::pad(&mut buffer, n, 2).unwrap(); +/// assert_eq!(padded_msg, b"test"); +/// assert_eq!(NoPadding::unpad(&padded_msg).unwrap(), msg); +/// ``` +pub enum NoPadding {} + +impl Padding for NoPadding { + fn pad_block(block: &mut [u8], pos: usize) -> Result<(), PadError> { + if pos % block.len() != 0 { + Err(PadError)? + } + Ok(()) + } + + fn pad(buf: &mut [u8], pos: usize, block_size: usize) -> Result<&mut [u8], PadError> { + if pos % block_size != 0 { + Err(PadError)? + } + Ok(&mut buf[..pos]) + } + + fn unpad(data: &[u8]) -> Result<&[u8], UnpadError> { + Ok(data) + } +} |