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use std::convert::TryFrom;
use std::sync::Mutex;
use win_crypto_ng::symmetric as cng;
use crate::crypto::mem::Protected;
use crate::crypto::symmetric::Mode;
use crate::{Error, Result};
use crate::types::SymmetricAlgorithm;
struct KeyWrapper {
key: Mutex<cng::SymmetricAlgorithmKey>,
iv: Option<Protected>,
}
impl KeyWrapper {
fn new(key: cng::SymmetricAlgorithmKey, iv: Option<Vec<u8>>) -> KeyWrapper {
KeyWrapper {
key: Mutex::new(key),
iv: iv.map(|iv| iv.into()),
}
}
}
impl Mode for KeyWrapper {
fn block_size(&self) -> usize {
self.key.lock().expect("Mutex not to be poisoned")
.block_size().expect("CNG not to fail internally")
}
fn encrypt(
&mut self,
dst: &mut [u8],
src: &[u8],
) -> Result<()> {
let block_size = Mode::block_size(self);
// If necessary, round up to the next block size and pad with zeroes
// NOTE: In theory CFB doesn't need this but CNG always requires
// passing full blocks.
let mut _src = vec![];
let missing = (block_size - (src.len() % block_size)) % block_size;
let src = if missing != 0 {
_src = vec![0u8; src.len() + missing];
_src[..src.len()].copy_from_slice(src);
&_src
} else {
src
};
let len = std::cmp::min(src.len(), dst.len());
let buffer = cng::SymmetricAlgorithmKey::encrypt(
&*self.key.lock().expect("Mutex not to be poisoned"),
self.iv.as_deref_mut(), src, None)?;
Ok(dst[..len].copy_from_slice(&buffer.as_slice()[..len]))
}
fn decrypt(
&mut self,
dst: &mut [u8],
src: &[u8],
) -> Result<()> {
let block_size = Mode::block_size(self);
// If necessary, round up to the next block size and pad with zeroes
// NOTE: In theory CFB doesn't need this but CNG always requires
// passing full blocks.
let mut _src = vec![];
let missing = (block_size - (src.len() % block_size)) % block_size;
let src = if missing != 0 {
_src = vec![0u8; src.len() + missing];
_src[..src.len()].copy_from_slice(src);
&_src
} else {
src
};
let len = std::cmp::min(src.len(), dst.len());
let buffer = cng::SymmetricAlgorithmKey::decrypt(
&*self.key.lock().expect("Mutex not to be poisoned"),
self.iv.as_deref_mut(), src, None)?;
dst[..len].copy_from_slice(&buffer.as_slice()[..len]);
Ok(())
}
}
#[derive(Debug, thiserror::Error)]
#[error("Unsupported algorithm: {0}")]
pub struct UnsupportedAlgorithm(SymmetricAlgorithm);
assert_send_and_sync!(UnsupportedAlgorithm);
impl From<UnsupportedAlgorithm> for Error {
fn from(value: UnsupportedAlgorithm) -> Error {
Error::UnsupportedSymmetricAlgorithm(value.0)
}
}
impl TryFrom<SymmetricAlgorithm> for (cng::SymmetricAlgorithmId, usize) {
type Error = UnsupportedAlgorithm;
fn try_from(value: SymmetricAlgorithm) -> std::result::Result<Self, Self::Error> {
Ok(match value {
SymmetricAlgorithm::TripleDES => (cng::SymmetricAlgorithmId::TripleDes, 168),
SymmetricAlgorithm::AES128 => (cng::SymmetricAlgorithmId::Aes, 128),
SymmetricAlgorithm::AES192 => (cng::SymmetricAlgorithmId::Aes, 192),
SymmetricAlgorithm::AES256 => (cng::SymmetricAlgorithmId::Aes, 256),
algo => Err(UnsupportedAlgorithm(algo))?,
})
}
}
impl SymmetricAlgorithm {
/// Returns whether this algorithm is supported by the crypto backend.
pub(crate) fn is_supported_by_backend(&self) -> bool {
use self::SymmetricAlgorithm::*;
match self {
AES128 | AES192 | AES256 | TripleDES => true,
_ => false,
}
}
/// Creates a symmetric cipher context for encrypting in CFB mode.
pub(crate) fn make_encrypt_cfb(self, key: &[u8], iv: Vec<u8>) -> Result<Box<dyn Mode>> {
let (algo, _) = TryFrom::try_from(self)?;
let algo = cng::SymmetricAlgorithm::open(algo, cng::ChainingMode::Cfb)?;
let mut key = algo.new_key(key)?;
// Use full-block CFB mode as expected everywhere else (by default it's
// set to 8-bit CFB)
key.set_msg_block_len(key.block_size()?)?;
Ok(Box::new(KeyWrapper::new(key, Some(iv))))
}
/// Creates a symmetric cipher context for decrypting in CFB mode.
pub(crate) fn make_decrypt_cfb(self, key: &[u8], iv: Vec<u8>) -> Result<Box<dyn Mode>> {
Self::make_encrypt_cfb(self, key, iv)
}
/// Creates a symmetric cipher context for encrypting in ECB mode.
pub(crate) fn make_encrypt_ecb(self, key: &[u8]) -> Result<Box<dyn Mode>> {
let (algo, _) = TryFrom::try_from(self)?;
let algo = cng::SymmetricAlgorithm::open(algo, cng::ChainingMode::Ecb)?;
let key = algo.new_key(key)?;
Ok(Box::new(KeyWrapper::new(key, None)))
}
/// Creates a symmetric cipher context for decrypting in ECB mode.
pub(crate) fn make_decrypt_ecb(self, key: &[u8]) -> Result<Box<dyn Mode>> {
Self::make_encrypt_ecb(self, key)
}
}
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