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Separate file crypto wrappers, starting with AES-CBC (#298)

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* refactor key wrapping with tests

* remove backwards compatiblity tests

* adds AES-CBC tests for IV and RNG
This commit is contained in:
kaczmarczyck
2021-03-31 16:41:20 +02:00
committed by GitHub
parent c596f785ff
commit e7797a5683
3 changed files with 157 additions and 91 deletions
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58
src/ctap/pin_protocol.rs
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@@ -13,13 +13,12 @@
// limitations under the License.
use crate::ctap::client_pin::PIN_TOKEN_LENGTH;
use crate::ctap::crypto_wrapper::{aes256_cbc_decrypt, aes256_cbc_encrypt};
use crate::ctap::data_formats::{CoseKey, PinUvAuthProtocol};
use crate::ctap::status_code::Ctap2StatusCode;
use alloc::boxed::Box;
use alloc::vec;
use alloc::vec::Vec;
use core::convert::TryInto;
use crypto::cbc::{cbc_decrypt, cbc_encrypt};
use crypto::hkdf::hkdf_empty_salt_256;
#[cfg(test)]
use crypto::hmac::hmac_256;
@@ -135,61 +134,6 @@ pub trait SharedSecret {
fn authenticate(&self, message: &[u8]) -> Vec<u8>;
}
fn aes256_cbc_encrypt(
rng: &mut dyn Rng256,
aes_enc_key: &crypto::aes256::EncryptionKey,
plaintext: &[u8],
has_iv: bool,
) -> Result<Vec<u8>, Ctap2StatusCode> {
if plaintext.len() % 16 != 0 {
return Err(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER);
}
let iv = if has_iv {
let random_bytes = rng.gen_uniform_u8x32();
*array_ref!(random_bytes, 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 has_iv { iv.to_vec() } else { vec![] };
ciphertext.extend(blocks.iter().flatten());
Ok(ciphertext)
}
fn aes256_cbc_decrypt(
aes_enc_key: &crypto::aes256::EncryptionKey,
ciphertext: &[u8],
has_iv: bool,
) -> Result<Vec<u8>, Ctap2StatusCode> {
if ciphertext.len() % 16 != 0 {
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 has_iv {
block_len -= 1;
let iv_block = block_iter
.next()
.ok_or(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER)?;
*array_ref!(iv_block, 0, 16)
} else {
[0u8; 16]
};
let mut blocks = Vec::with_capacity(block_len);
for block in block_iter {
blocks.push(*array_ref!(block, 0, 16));
}
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>>())
}
fn verify_v1(key: &[u8], message: &[u8], signature: &[u8]) -> Result<(), Ctap2StatusCode> {
if signature.len() != 16 {
return Err(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER);