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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.
use nix::unistd::getuid;
use openssl::ec::{EcGroup, EcKey};
use openssl::error::ErrorStack;
use openssl::nid::Nid;
use openssl::pkey::{PKey, PKeyRef, Private, Public};
use openssl::pkey_ctx::PkeyCtx;
use openssl::x509::X509;
use android_hardware_security_keymint::aidl::android::hardware::security::keymint::{
Digest::Digest, EcCurve::EcCurve, ErrorCode::ErrorCode, KeyPurpose::KeyPurpose,
SecurityLevel::SecurityLevel,
};
use android_system_keystore2::aidl::android::system::keystore2::{
Domain::Domain, IKeystoreSecurityLevel::IKeystoreSecurityLevel, KeyDescriptor::KeyDescriptor,
KeyMetadata::KeyMetadata,
};
use keystore2_test_utils::{
authorizations, get_keystore_service, key_generations, key_generations::Error,
};
/// This macro is used to verify that the key agreement works for the given curve.
macro_rules! test_ec_key_agree {
( $test_name:ident, $ec_curve:expr ) => {
#[test]
fn $test_name() {
perform_ec_key_agreement($ec_curve);
}
};
}
// Get the KeyMint key's public part.
fn get_keymint_public_key(keymint_key: &KeyMetadata) -> Result<PKey<Public>, ErrorStack> {
let cert_bytes = keymint_key.certificate.as_ref().unwrap();
let cert = X509::from_der(cert_bytes.as_ref()).unwrap();
cert.public_key()
}
// Perform local ECDH between the two keys and check the derived secrets are the same.
fn check_agreement(
sec_level: &binder::Strong<dyn IKeystoreSecurityLevel>,
keymint_key: &KeyDescriptor,
keymint_pub_key: &PKey<Public>,
local_key: &PKeyRef<Private>,
local_pub_key: &[u8],
) {
let authorizations = authorizations::AuthSetBuilder::new().purpose(KeyPurpose::AGREE_KEY);
let key_agree_op = sec_level.createOperation(keymint_key, &authorizations, false).unwrap();
assert!(key_agree_op.iOperation.is_some());
let op = key_agree_op.iOperation.unwrap();
let secret = op.finish(Some(local_pub_key), None).unwrap();
assert!(secret.is_some());
let mut ctx = PkeyCtx::new(local_key).unwrap();
ctx.derive_init().unwrap();
ctx.derive_set_peer(keymint_pub_key).unwrap();
let mut peer_secret = vec![];
ctx.derive_to_vec(&mut peer_secret).unwrap();
assert_eq!(secret.unwrap(), peer_secret);
}
fn ec_curve_to_openrssl_curve_name(ec_curve: &EcCurve) -> Nid {
match *ec_curve {
EcCurve::P_224 => Nid::SECP224R1,
EcCurve::P_256 => Nid::X9_62_PRIME256V1,
EcCurve::P_384 => Nid::SECP384R1,
EcCurve::P_521 => Nid::SECP521R1,
_ => Nid::UNDEF,
}
}
/// Generate two EC keys with given curve from KeyMint and OpeanSSL. Perform local ECDH between
/// them and verify that the derived secrets are the same.
fn perform_ec_key_agreement(ec_curve: EcCurve) {
let keystore2 = get_keystore_service();
let sec_level = keystore2.getSecurityLevel(SecurityLevel::TRUSTED_ENVIRONMENT).unwrap();
let openssl_ec_curve = ec_curve_to_openrssl_curve_name(&ec_curve);
let alias = format!("ks_ec_test_key_agree_{}", getuid());
let keymint_key = key_generations::generate_ec_agree_key(
&sec_level,
ec_curve,
Digest::SHA_2_256,
Domain::APP,
-1,
Some(alias),
)
.unwrap();
let keymint_pub_key = get_keymint_public_key(&keymint_key).unwrap();
let group = EcGroup::from_curve_name(openssl_ec_curve).unwrap();
let ec_key = EcKey::generate(&group).unwrap();
let local_key = PKey::from_ec_key(ec_key).unwrap();
let local_pub_key = local_key.public_key_to_der().unwrap();
check_agreement(&sec_level, &keymint_key.key, &keymint_pub_key, &local_key, &local_pub_key);
}
test_ec_key_agree!(test_ec_p224_key_agreement, EcCurve::P_224);
test_ec_key_agree!(test_ec_p256_key_agreement, EcCurve::P_256);
test_ec_key_agree!(test_ec_p384_key_agreement, EcCurve::P_384);
test_ec_key_agree!(test_ec_p521_key_agreement, EcCurve::P_521);
/// Generate two EC keys with curve `CURVE_25519` from KeyMint and OpeanSSL.
/// Perform local ECDH between them and verify that the derived secrets are the same.
#[test]
fn keystore2_ec_25519_agree_key_success() {
let keystore2 = get_keystore_service();
let sec_level = keystore2.getSecurityLevel(SecurityLevel::TRUSTED_ENVIRONMENT).unwrap();
let alias = format!("ks_ec_25519_test_key_agree_{}", getuid());
let keymint_key = key_generations::generate_ec_agree_key(
&sec_level,
EcCurve::CURVE_25519,
Digest::NONE,
Domain::APP,
-1,
Some(alias),
)
.unwrap();
let keymint_pub_key = get_keymint_public_key(&keymint_key).unwrap();
let local_key = PKey::generate_x25519().unwrap();
let local_pub_key = local_key.public_key_to_der().unwrap();
check_agreement(&sec_level, &keymint_key.key, &keymint_pub_key, &local_key, &local_pub_key);
}
/// Generate two EC keys with different curves and try to perform local ECDH. Since keys are using
/// different curves operation should fail with `ErrorCode:INVALID_ARGUMENT`.
#[test]
fn keystore2_ec_agree_key_with_different_curves_fail() {
let keystore2 = get_keystore_service();
let sec_level = keystore2.getSecurityLevel(SecurityLevel::TRUSTED_ENVIRONMENT).unwrap();
let alias = format!("ks_test_key_agree_fail{}", getuid());
let keymint_key = key_generations::generate_ec_agree_key(
&sec_level,
EcCurve::P_256,
Digest::SHA_2_256,
Domain::APP,
-1,
Some(alias),
)
.unwrap();
let local_key = PKey::generate_x25519().unwrap();
let local_pub_key = local_key.public_key_to_der().unwrap();
// If the keys are using different curves KeyMint should fail with
// ErrorCode:INVALID_ARGUMENT.
let authorizations = authorizations::AuthSetBuilder::new().purpose(KeyPurpose::AGREE_KEY);
let key_agree_op = sec_level.createOperation(&keymint_key.key, &authorizations, false).unwrap();
assert!(key_agree_op.iOperation.is_some());
let op = key_agree_op.iOperation.unwrap();
let result = key_generations::map_ks_error(op.finish(Some(&local_pub_key), None));
assert!(result.is_err());
assert_eq!(Error::Km(ErrorCode::INVALID_ARGUMENT), result.unwrap_err());
}
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