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Remove the software-specific Decrypt16BytesBlock and Encrypt16BytesBlock traits

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They assume blocks are encrypted/decrypted one at a time. To avoid one syscall
per block, it is preferable to encrypt/decrypt the data at once.

Change-Id: I795c8f5b7901a1b55fa3b06fa45fe57ab19d06ea
This commit is contained in:
Julien Cretin
2022-01-20 15:10:30 +01:00
committed by Julien Cretin
parent 98c9191679
commit b59df7001f
6 changed files with 65 additions and 109 deletions
Download Patch File Download Diff File Expand all files Collapse all files

41
src/ctap/crypto_wrapper.rs
View File

@@ -13,7 +13,6 @@
// limitations under the License.
use crate::ctap::status_code::Ctap2StatusCode;
use alloc::vec;
use alloc::vec::Vec;
use crypto::cbc::{cbc_decrypt, cbc_encrypt};
use crypto::rng256::Rng256;
@@ -28,20 +27,17 @@ pub fn aes256_cbc_encrypt(
if plaintext.len() % 16 != 0 {
return Err(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER);
}
let mut ciphertext = Vec::with_capacity(plaintext.len() + 16 * embeds_iv as usize);
let iv = if embeds_iv {
let random_bytes = rng.gen_uniform_u8x32();
*array_ref!(random_bytes, 0, 16)
ciphertext.extend_from_slice(&random_bytes[..16]);
*array_ref!(ciphertext, 0, 16)
} else {
[0u8; 16]
};
let mut blocks = Vec::with_capacity(plaintext.len() / 16);
// TODO(https://github.com/rust-lang/rust/issues/74985) Use array_chunks when stable.
for block in plaintext.chunks_exact(16) {
blocks.push(*array_ref!(block, 0, 16));
}
cbc_encrypt(aes_enc_key, iv, &mut blocks);
let mut ciphertext = if embeds_iv { iv.to_vec() } else { vec![] };
ciphertext.extend(blocks.iter().flatten());
let start = ciphertext.len();
ciphertext.extend_from_slice(plaintext);
cbc_encrypt(aes_enc_key, iv, &mut ciphertext[start..]);
Ok(ciphertext)
}
@@ -51,28 +47,19 @@ pub fn aes256_cbc_decrypt(
ciphertext: &[u8],
embeds_iv: bool,
) -> Result<Vec<u8>, Ctap2StatusCode> {
if ciphertext.len() % 16 != 0 {
if ciphertext.len() % 16 != 0 || (embeds_iv && ciphertext.is_empty()) {
return Err(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER);
}
let mut block_len = ciphertext.len() / 16;
// TODO(https://github.com/rust-lang/rust/issues/74985) Use array_chunks when stable.
let mut block_iter = ciphertext.chunks_exact(16);
let iv = if embeds_iv {
block_len -= 1;
let iv_block = block_iter
.next()
.ok_or(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER)?;
*array_ref!(iv_block, 0, 16)
let (iv, ciphertext) = if embeds_iv {
let (iv, ciphertext) = ciphertext.split_at(16);
(*array_ref!(iv, 0, 16), ciphertext)
} else {
[0u8; 16]
([0u8; 16], ciphertext)
};
let mut blocks = Vec::with_capacity(block_len);
for block in block_iter {
blocks.push(*array_ref!(block, 0, 16));
}
let mut plaintext = ciphertext.to_vec();
let aes_dec_key = crypto::aes256::DecryptionKey::new(aes_enc_key);
cbc_decrypt(&aes_dec_key, iv, &mut blocks);
Ok(blocks.iter().flatten().cloned().collect::<Vec<u8>>())
cbc_decrypt(&aes_dec_key, iv, &mut plaintext);
Ok(plaintext)
}
#[cfg(test)]