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/*
* Copyright 2022 The Android Open Source Project
*
* 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.
*/
//! Bare metal wrapper around libopen_dice.
#![no_std]
use core::fmt;
use core::result;
use open_dice_cbor_bindgen::DiceHash;
use open_dice_cbor_bindgen::DiceResult;
use open_dice_cbor_bindgen::DiceResult_kDiceResultBufferTooSmall as DICE_RESULT_BUFFER_TOO_SMALL;
use open_dice_cbor_bindgen::DiceResult_kDiceResultInvalidInput as DICE_RESULT_INVALID_INPUT;
use open_dice_cbor_bindgen::DiceResult_kDiceResultOk as DICE_RESULT_OK;
use open_dice_cbor_bindgen::DiceResult_kDiceResultPlatformError as DICE_RESULT_PLATFORM_ERROR;
pub mod bcc;
const CDI_SIZE: usize = open_dice_cbor_bindgen::DICE_CDI_SIZE as usize;
const HASH_SIZE: usize = open_dice_cbor_bindgen::DICE_HASH_SIZE as usize;
/// Array type of CDIs.
pub type Cdi = [u8; CDI_SIZE];
/// Array type of hashes used by DICE.
pub type Hash = [u8; HASH_SIZE];
/// Error type used by DICE.
pub enum Error {
/// Provided input was invalid.
InvalidInput,
/// Provided buffer was too small.
BufferTooSmall,
/// Unexpected platform error.
PlatformError,
/// Unexpected return value.
Unknown(DiceResult),
}
impl fmt::Debug for Error {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match self {
Error::InvalidInput => write!(f, "invalid input"),
Error::BufferTooSmall => write!(f, "buffer too small"),
Error::PlatformError => write!(f, "platform error"),
Error::Unknown(n) => write!(f, "unknown error: {}", n),
}
}
}
/// Result of DICE functions.
pub type Result<T> = result::Result<T, Error>;
fn check_call(ret: DiceResult) -> Result<()> {
match ret {
DICE_RESULT_OK => Ok(()),
DICE_RESULT_INVALID_INPUT => Err(Error::InvalidInput),
DICE_RESULT_BUFFER_TOO_SMALL => Err(Error::BufferTooSmall),
DICE_RESULT_PLATFORM_ERROR => Err(Error::PlatformError),
n => Err(Error::Unknown(n)),
}
}
fn ctx() -> *mut core::ffi::c_void {
core::ptr::null_mut()
}
/// Hash the provided input using DICE's default hash function.
pub fn hash(bytes: &[u8]) -> Result<Hash> {
let mut output: Hash = [0; HASH_SIZE];
// SAFETY - DiceHash takes a sized input buffer and writes to a constant-sized output buffer.
check_call(unsafe { DiceHash(ctx(), bytes.as_ptr(), bytes.len(), output.as_mut_ptr()) })?;
Ok(output)
}