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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
use crate::{
error::*,
pk11::{context::HashAlgorithm, slot, types::SymKey},
util::{ensure_nss_initialized, map_nss_secstatus, sec_item_as_slice, ScopedPtr},
};
use std::{
mem,
os::raw::{c_uchar, c_uint, c_ulong},
ptr,
};
pub fn hkdf_expand(
digest_alg: &HashAlgorithm,
key_bytes: &[u8],
info: &[u8],
len: usize,
) -> Result<Vec<u8>> {
ensure_nss_initialized();
let mech = digest_alg.as_hkdf_mechanism();
// Most of the following code is inspired by the Firefox WebCrypto implementation:
// Except that we only do the expand part, which explains why we use null pointers below.
let mut hkdf_params = nss_sys::CK_NSS_HKDFParams {
bExtract: nss_sys::CK_FALSE,
pSalt: ptr::null_mut(),
ulSaltLen: 0,
bExpand: nss_sys::CK_TRUE,
pInfo: info.as_ptr() as *mut u8,
ulInfoLen: c_ulong::try_from(info.len())?,
};
let mut params = nss_sys::SECItem {
type_: nss_sys::SECItemType::siBuffer as u32,
data: &mut hkdf_params as *mut _ as *mut c_uchar,
len: u32::try_from(mem::size_of::<nss_sys::CK_NSS_HKDFParams>())?,
};
let base_key = import_sym_key(mech.into(), nss_sys::CKA_WRAP.into(), key_bytes)?;
let derived_len = i32::try_from(len)?;
let sym_key = unsafe {
SymKey::from_ptr(
// CKM_SHA512_HMAC and CKA_SIGN are key type and usage attributes of the
// derived symmetric key and don't matter because we ignore them anyway.
nss_sys::PK11_Derive(
base_key.as_mut_ptr(),
mech.into(),
&mut params,
nss_sys::CKM_SHA512_HMAC.into(),
nss_sys::CKA_SIGN.into(),
derived_len,
),
)?
};
map_nss_secstatus(|| unsafe { nss_sys::PK11_ExtractKeyValue(sym_key.as_mut_ptr()) })?;
// This doesn't leak, because the SECItem* returned by PK11_GetKeyData
// just refers to a buffer managed by `sym_key` which we copy into `out`.
let mut key_data = unsafe { *nss_sys::PK11_GetKeyData(sym_key.as_mut_ptr()) };
if u32::try_from(len)? > key_data.len {
return Err(ErrorKind::InternalError.into());
}
let buf = unsafe { sec_item_as_slice(&mut key_data)? };
Ok(buf.to_vec())
}
/// Safe wrapper around PK11_ImportSymKey that
/// de-allocates memory when the key goes out of
/// scope.
pub(crate) fn import_sym_key(
mechanism: nss_sys::CK_MECHANISM_TYPE,
operation: nss_sys::CK_ATTRIBUTE_TYPE,
buf: &[u8],
) -> Result<SymKey> {
ensure_nss_initialized();
let mut item = nss_sys::SECItem {
type_: nss_sys::SECItemType::siBuffer as u32,
data: buf.as_ptr() as *mut c_uchar,
len: c_uint::try_from(buf.len())?,
};
let slot = slot::get_internal_slot()?;
unsafe {
SymKey::from_ptr(nss_sys::PK11_ImportSymKey(
slot.as_mut_ptr(),
mechanism,
nss_sys::PK11Origin::PK11_OriginUnwrap as u32,
operation,
&mut item,
ptr::null_mut(),
))
}
}