wasefire 0.8.1

// Copyright 2022 Google LLC
//
// 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.

//! Provides AES-CCM as defined by Bluetooth.

use alloc::vec;
use alloc::vec::Vec;

use wasefire_applet_api::crypto::ccm as api;

use crate::{Error, convert_bool, convert_unit};

/// Whether AES-CCM is supported.
pub fn is_supported() -> bool {
    convert_bool(unsafe { api::is_supported() }).unwrap_or(false)
}

/// Returns the ciphertext given a cleartext, a key, and a nonce.
pub fn encrypt(key: &[u8; 16], nonce: &[u8; 8], clear: &[u8]) -> Result<Vec<u8>, Error> {
    let len = clear.len();
    let mut cipher = vec![0; len + 4];
    let params = api::encrypt::Params {
        key: key.as_ptr(),
        iv: nonce.as_ptr(),
        len,
        clear: clear.as_ptr(),
        cipher: cipher.as_mut_ptr(),
    };
    convert_unit(unsafe { api::encrypt(params) })?;
    Ok(cipher)
}

/// Returns the cleartext given a ciphertext, a key, and a nonce.
pub fn decrypt(key: &[u8; 16], nonce: &[u8; 8], cipher: &[u8]) -> Result<Vec<u8>, Error> {
    let len = cipher.len().checked_sub(4).ok_or(Error::user(0))?;
    let mut clear = vec![0; len];
    let params = api::decrypt::Params {
        key: key.as_ptr(),
        iv: nonce.as_ptr(),
        len,
        cipher: cipher.as_ptr(),
        clear: clear.as_mut_ptr(),
    };
    convert_unit(unsafe { api::decrypt(params) })?;
    Ok(clear)
}