keymaster0_engine.cpp - platform/system/keymaster - Git at Google

 /*
  * Copyright 2015 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.
  */

 #include "keymaster0_engine.h"

 #include <assert.h>

 #include <memory>

 #define LOG_TAG "Keymaster0Engine"
 #include <cutils/log.h>

 #include "keymaster/android_keymaster_utils.h"

 #include <openssl/ec_key.h>
 #include <openssl/ecdsa.h>

 #include "openssl_utils.h"

 using std::shared_ptr;
 using std::unique_ptr;

 namespace keymaster {

 // int Keymaster0Engine::rsa_index_ = -1;
 // int Keymaster0Engine::ec_key_index_ = -1;
 Keymaster0Engine* Keymaster0Engine::instance_ = nullptr;
 const RSA_METHOD Keymaster0Engine::rsa_method_ = {
     .common =
         {
             0,  // references
             1   // is_static
         },
     .app_data = nullptr,
     .init = nullptr,
     .finish = nullptr,
     .size = nullptr,
     .sign = nullptr,
     .verify = nullptr,

     .encrypt = nullptr,
     .sign_raw = nullptr,
     .decrypt = nullptr,
     .verify_raw = nullptr,

     .private_transform = Keymaster0Engine::rsa_private_transform,

     .mod_exp = nullptr,
     .bn_mod_exp = BN_mod_exp_mont,

     .flags = RSA_FLAG_OPAQUE,

     .keygen = nullptr,
     .supports_digest = nullptr,
 };

 const ECDSA_METHOD Keymaster0Engine::ecdsa_method_ = {
     .common =
         {
             0,  // references
             1   // is_static
         },
     .app_data = nullptr,
     .init = nullptr,
     .finish = nullptr,
     .group_order_size = nullptr,
     .sign = Keymaster0Engine::ecdsa_sign,
     .verify = nullptr,
     .flags = ECDSA_FLAG_OPAQUE,
 };

 Keymaster0Engine::Keymaster0Engine(const keymaster0_device_t* keymaster0_device)
     : keymaster0_device_(keymaster0_device), engine_(ENGINE_new()), supports_ec_(false) {
     assert(!instance_);
     instance_ = this;

     rsa_index_ = RSA_get_ex_new_index(0 /* argl */, NULL /* argp */, NULL /* new_func */,
                                       keyblob_dup, keyblob_free);
     ec_key_index_ = EC_KEY_get_ex_new_index(0 /* argl */, NULL /* argp */, NULL /* new_func */,
                                             keyblob_dup, keyblob_free);

     ENGINE_set_RSA_method(engine_, &rsa_method_, sizeof(rsa_method_));

     if ((keymaster0_device_->flags & KEYMASTER_SUPPORTS_EC) != 0) {
         supports_ec_ = true;
         ENGINE_set_ECDSA_method(engine_, &ecdsa_method_, sizeof(ecdsa_method_));
     }
 }

 Keymaster0Engine::~Keymaster0Engine() {
     if (keymaster0_device_)
         keymaster0_device_->common.close(
             reinterpret_cast<hw_device_t*>(const_cast<keymaster0_device_t*>(keymaster0_device_)));
     ENGINE_free(engine_);
     instance_ = nullptr;
 }

 bool Keymaster0Engine::GenerateRsaKey(uint64_t public_exponent, uint32_t public_modulus,
                                       KeymasterKeyBlob* key_material) const {
     assert(key_material);
     keymaster_rsa_keygen_params_t params;
     params.public_exponent = public_exponent;
     params.modulus_size = public_modulus;

     uint8_t* key_blob = 0;
     if (keymaster0_device_->generate_keypair(keymaster0_device_, TYPE_RSA, &params, &key_blob,
                                              &key_material->key_material_size) < 0) {
         ALOGE("Error generating RSA key pair with keymaster0 device");
         return false;
     }
     unique_ptr<uint8_t, Malloc_Delete> key_blob_deleter(key_blob);
     key_material->key_material = dup_buffer(key_blob, key_material->key_material_size);
     return true;
 }

 bool Keymaster0Engine::GenerateEcKey(uint32_t key_size, KeymasterKeyBlob* key_material) const {
     assert(key_material);
     keymaster_ec_keygen_params_t params;
     params.field_size = key_size;

     uint8_t* key_blob = 0;
     if (keymaster0_device_->generate_keypair(keymaster0_device_, TYPE_EC, &params, &key_blob,
                                              &key_material->key_material_size) < 0) {
         ALOGE("Error generating EC key pair with keymaster0 device");
         return false;
     }
     unique_ptr<uint8_t, Malloc_Delete> key_blob_deleter(key_blob);
     key_material->key_material = dup_buffer(key_blob, key_material->key_material_size);
     return true;
 }

 bool Keymaster0Engine::ImportKey(keymaster_key_format_t key_format,
                                  const KeymasterKeyBlob& to_import,
                                  KeymasterKeyBlob* imported_key) const {
     assert(imported_key);
     if (key_format != KM_KEY_FORMAT_PKCS8)
         return false;

     uint8_t* key_blob = 0;
     if (keymaster0_device_->import_keypair(keymaster0_device_, to_import.key_material,
                                            to_import.key_material_size, &key_blob,
                                            &imported_key->key_material_size) < 0) {
         ALOGW("Error importing keypair with keymaster0 device");
         return false;
     }
     unique_ptr<uint8_t, Malloc_Delete> key_blob_deleter(key_blob);
     imported_key->key_material = dup_buffer(key_blob, imported_key->key_material_size);
     return true;
 }

 static keymaster_key_blob_t* duplicate_blob(const uint8_t* key_data, size_t key_data_size) {
     unique_ptr<uint8_t[]> key_material_copy(new uint8_t[key_data_size]);
     if (!key_material_copy)
         return nullptr;

     memcpy(key_material_copy.get(), key_data, key_data_size);
     unique_ptr<keymaster_key_blob_t> blob_copy(new keymaster_key_blob_t);
     blob_copy->key_material_size = key_data_size;
     blob_copy->key_material = key_material_copy.release();
     return blob_copy.release();
 }

 inline keymaster_key_blob_t* duplicate_blob(const keymaster_key_blob_t& blob) {
     return duplicate_blob(blob.key_material, blob.key_material_size);
 }

 RSA* Keymaster0Engine::BlobToRsaKey(const KeymasterKeyBlob& blob) const {
     // Create new RSA key (with engine methods) and insert blob
     unique_ptr<RSA, RSA_Delete> rsa(RSA_new_method(engine_));
     if (!rsa)
         return nullptr;

     keymaster_key_blob_t* blob_copy = duplicate_blob(blob);
     if (!blob_copy->key_material || !RSA_set_ex_data(rsa.get(), rsa_index_, blob_copy))
         return nullptr;

     // Copy public key into new RSA key
     unique_ptr<EVP_PKEY, EVP_PKEY_Delete> pkey(GetKeymaster0PublicKey(blob));
     if (!pkey)
         return nullptr;
     unique_ptr<RSA, RSA_Delete> public_rsa(EVP_PKEY_get1_RSA(pkey.get()));
     if (!public_rsa)
         return nullptr;
     rsa->n = BN_dup(public_rsa->n);
     rsa->e = BN_dup(public_rsa->e);
     if (!rsa->n || !rsa->e)
         return nullptr;

     return rsa.release();
 }

 EC_KEY* Keymaster0Engine::BlobToEcKey(const KeymasterKeyBlob& blob) const {
     // Create new EC key (with engine methods) and insert blob
     unique_ptr<EC_KEY, EC_Delete> ec_key(EC_KEY_new_method(engine_));
     if (!ec_key)
         return nullptr;

     keymaster_key_blob_t* blob_copy = duplicate_blob(blob);
     if (!blob_copy->key_material || !EC_KEY_set_ex_data(ec_key.get(), ec_key_index_, blob_copy))
         return nullptr;

     // Copy public key into new EC key
     unique_ptr<EVP_PKEY, EVP_PKEY_Delete> pkey(GetKeymaster0PublicKey(blob));
     if (!pkey)
         return nullptr;

     unique_ptr<EC_KEY, EC_Delete> public_ec_key(EVP_PKEY_get1_EC_KEY(pkey.get()));
     if (!public_ec_key)
         return nullptr;

     if (!EC_KEY_set_group(ec_key.get(), EC_KEY_get0_group(public_ec_key.get())) ||
         !EC_KEY_set_public_key(ec_key.get(), EC_KEY_get0_public_key(public_ec_key.get())))
         return nullptr;

     return ec_key.release();
 }

 const keymaster_key_blob_t* Keymaster0Engine::RsaKeyToBlob(const RSA* rsa) const {
     return reinterpret_cast<keymaster_key_blob_t*>(RSA_get_ex_data(rsa, rsa_index_));
 }

 const keymaster_key_blob_t* Keymaster0Engine::EcKeyToBlob(const EC_KEY* ec_key) const {
     return reinterpret_cast<keymaster_key_blob_t*>(EC_KEY_get_ex_data(ec_key, ec_key_index_));
 }

 /* static */
 int Keymaster0Engine::keyblob_dup(CRYPTO_EX_DATA* /* to */, const CRYPTO_EX_DATA* /* from */,
                                   void** from_d, int /* index */, long /* argl */,
                                   void* /* argp */) {
     keymaster_key_blob_t* blob = reinterpret_cast<keymaster_key_blob_t*>(*from_d);
     if (!blob)
         return 1;
     *from_d = duplicate_blob(*blob);
     if (*from_d)
         return 1;
     return 0;
 }

 /* static */
 void Keymaster0Engine::keyblob_free(void* /* parent */, void* ptr, CRYPTO_EX_DATA* /* data */,
                                     int /* index*/, long /* argl */, void* /* argp */) {
     keymaster_key_blob_t* blob = reinterpret_cast<keymaster_key_blob_t*>(ptr);
     if (blob) {
         delete[] blob->key_material;
         delete blob;
     }
 }

 /* static */
 int Keymaster0Engine::rsa_private_transform(RSA* rsa, uint8_t* out, const uint8_t* in, size_t len) {
     ALOGV("rsa_private_transform(%p, %p, %p, %u)", rsa, out, in, (unsigned)len);

     assert(instance_);
     return instance_->RsaPrivateTransform(rsa, out, in, len);
 }

 /* static */
 int Keymaster0Engine::ecdsa_sign(const uint8_t* digest, size_t digest_len, uint8_t* sig,
                                  unsigned int* sig_len, EC_KEY* ec_key) {
     ALOGV("ecdsa_sign(%p, %u, %p)", digest, (unsigned)digest_len, ec_key);
     assert(instance_);
     return instance_->EcdsaSign(digest, digest_len, sig, sig_len, ec_key);
 }

 bool Keymaster0Engine::Keymaster0Sign(const void* signing_params, const keymaster_key_blob_t& blob,
                                       const uint8_t* data, const size_t data_length,
                                       unique_ptr<uint8_t[], Malloc_Delete>* signature,
                                       size_t* signature_length) const {
     uint8_t* signed_data;
     int err = keymaster0_device_->sign_data(keymaster0_device_, signing_params, blob.key_material,
                                             blob.key_material_size, data, data_length, &signed_data,
                                             signature_length);
     if (err < 0) {
         ALOGE("Keymaster0 signing failed with error %d", err);
         return false;
     }

     signature->reset(signed_data);
     return true;
 }

 EVP_PKEY* Keymaster0Engine::GetKeymaster0PublicKey(const KeymasterKeyBlob& blob) const {
     uint8_t* pub_key_data;
     size_t pub_key_data_length;
     int err = keymaster0_device_->get_keypair_public(keymaster0_device_, blob.key_material,
                                                      blob.key_material_size, &pub_key_data,
                                                      &pub_key_data_length);
     if (err < 0) {
         ALOGE("Error %d extracting public key", err);
         return nullptr;
     }
     unique_ptr<uint8_t, Malloc_Delete> pub_key(pub_key_data);

     const uint8_t* p = pub_key_data;
     return d2i_PUBKEY(nullptr /* allocate new struct */, &p, pub_key_data_length);
 }

 int Keymaster0Engine::RsaPrivateTransform(RSA* rsa, uint8_t* out, const uint8_t* in,
                                           size_t len) const {
     const keymaster_key_blob_t* key_blob = RsaKeyToBlob(rsa);
     if (key_blob == NULL) {
         ALOGE("key had no key_blob!");
         return 0;
     }

     keymaster_rsa_sign_params_t sign_params = {DIGEST_NONE, PADDING_NONE};
     unique_ptr<uint8_t[], Malloc_Delete> signature;
     size_t signature_length;
     if (!Keymaster0Sign(&sign_params, *key_blob, in, len, &signature, &signature_length))
         return 0;
     Eraser eraser(signature.get(), signature_length);

     if (signature_length > len) {
         /* The result of the RSA operation can never be larger than the size of
          * the modulus so we assume that the result has extra zeros on the
          * left. This provides attackers with an oracle, but there's nothing
          * that we can do about it here. */
         memcpy(out, signature.get() + signature_length - len, len);
     } else if (signature_length < len) {
         /* If the keymaster0 implementation returns a short value we assume that
          * it's because it removed leading zeros from the left side. This is
          * bad because it provides attackers with an oracle but we cannot do
          * anything about a broken keymaster0 implementation here. */
         memset(out, 0, len);
         memcpy(out + len - signature_length, signature.get(), signature_length);
     } else {
         memcpy(out, signature.get(), len);
     }

     ALOGV("rsa=%p keystore_rsa_priv_dec successful", rsa);
     return 1;
 }

 int Keymaster0Engine::EcdsaSign(const uint8_t* digest, size_t digest_len, uint8_t* sig,
                                 unsigned int* sig_len, EC_KEY* ec_key) const {
     const keymaster_key_blob_t* key_blob = EcKeyToBlob(ec_key);
     if (key_blob == NULL) {
         ALOGE("key had no key_blob!");
         return 0;
     }

     keymaster_ec_sign_params_t sign_params = {DIGEST_NONE};
     unique_ptr<uint8_t[], Malloc_Delete> signature;
     size_t signature_length;
     if (!Keymaster0Sign(&sign_params, *key_blob, digest, digest_len, &signature, &signature_length))
         return 0;
     Eraser eraser(signature.get(), signature_length);

     if (signature_length == 0) {
         ALOGW("No valid signature returned");
         return 0;
     } else if (signature_length > ECDSA_size(ec_key)) {
         ALOGW("Signature is too large");
         return 0;
     } else {
         memcpy(sig, signature.get(), signature_length);
         *sig_len = signature_length;
     }

     ALOGV("ecdsa_sign(%p, %u, %p) => success", digest, (unsigned)digest_len, ec_key);
     return 1;
 }

 }  // namespace keymaster
	/*
	* Copyright 2015 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.
	*/

	#include "keymaster0_engine.h"

	#include <assert.h>

	#include <memory>

	#define LOG_TAG "Keymaster0Engine"
	#include <cutils/log.h>

	#include "keymaster/android_keymaster_utils.h"

	#include <openssl/ec_key.h>
	#include <openssl/ecdsa.h>

	#include "openssl_utils.h"

	using std::shared_ptr;
	using std::unique_ptr;

	namespace keymaster {

	// int Keymaster0Engine::rsa_index_ = -1;
	// int Keymaster0Engine::ec_key_index_ = -1;
	Keymaster0Engine* Keymaster0Engine::instance_ = nullptr;
	const RSA_METHOD Keymaster0Engine::rsa_method_ = {
	.common =
	{
	0, // references
	1 // is_static
	},
	.app_data = nullptr,
	.init = nullptr,
	.finish = nullptr,
	.size = nullptr,
	.sign = nullptr,
	.verify = nullptr,

	.encrypt = nullptr,
	.sign_raw = nullptr,
	.decrypt = nullptr,
	.verify_raw = nullptr,

	.private_transform = Keymaster0Engine::rsa_private_transform,

	.mod_exp = nullptr,
	.bn_mod_exp = BN_mod_exp_mont,

	.flags = RSA_FLAG_OPAQUE,

	.keygen = nullptr,
	.supports_digest = nullptr,
	};

	const ECDSA_METHOD Keymaster0Engine::ecdsa_method_ = {
	.common =
	{
	0, // references
	1 // is_static
	},
	.app_data = nullptr,
	.init = nullptr,
	.finish = nullptr,
	.group_order_size = nullptr,
	.sign = Keymaster0Engine::ecdsa_sign,
	.verify = nullptr,
	.flags = ECDSA_FLAG_OPAQUE,
	};

	Keymaster0Engine::Keymaster0Engine(const keymaster0_device_t* keymaster0_device)
	: keymaster0_device_(keymaster0_device), engine_(ENGINE_new()), supports_ec_(false) {
	assert(!instance_);
	instance_ = this;

	rsa_index_ = RSA_get_ex_new_index(0 /* argl /, NULL / argp /, NULL / new_func */,
	keyblob_dup, keyblob_free);
	ec_key_index_ = EC_KEY_get_ex_new_index(0 /* argl /, NULL / argp /, NULL / new_func */,
	keyblob_dup, keyblob_free);

	ENGINE_set_RSA_method(engine_, &rsa_method_, sizeof(rsa_method_));

	if ((keymaster0_device_->flags & KEYMASTER_SUPPORTS_EC) != 0) {
	supports_ec_ = true;
	ENGINE_set_ECDSA_method(engine_, &ecdsa_method_, sizeof(ecdsa_method_));
	}
	}

	Keymaster0Engine::~Keymaster0Engine() {
	if (keymaster0_device_)
	keymaster0_device_->common.close(
	reinterpret_cast<hw_device_t>(const_cast<keymaster0_device_t>(keymaster0_device_)));
	ENGINE_free(engine_);
	instance_ = nullptr;
	}

	bool Keymaster0Engine::GenerateRsaKey(uint64_t public_exponent, uint32_t public_modulus,
	KeymasterKeyBlob* key_material) const {
	assert(key_material);
	keymaster_rsa_keygen_params_t params;
	params.public_exponent = public_exponent;
	params.modulus_size = public_modulus;

	uint8_t* key_blob = 0;
	if (keymaster0_device_->generate_keypair(keymaster0_device_, TYPE_RSA, &params, &key_blob,
	&key_material->key_material_size) < 0) {
	ALOGE("Error generating RSA key pair with keymaster0 device");
	return false;
	}
	unique_ptr<uint8_t, Malloc_Delete> key_blob_deleter(key_blob);
	key_material->key_material = dup_buffer(key_blob, key_material->key_material_size);
	return true;
	}

	bool Keymaster0Engine::GenerateEcKey(uint32_t key_size, KeymasterKeyBlob* key_material) const {
	assert(key_material);
	keymaster_ec_keygen_params_t params;
	params.field_size = key_size;

	uint8_t* key_blob = 0;
	if (keymaster0_device_->generate_keypair(keymaster0_device_, TYPE_EC, &params, &key_blob,
	&key_material->key_material_size) < 0) {
	ALOGE("Error generating EC key pair with keymaster0 device");
	return false;
	}
	unique_ptr<uint8_t, Malloc_Delete> key_blob_deleter(key_blob);
	key_material->key_material = dup_buffer(key_blob, key_material->key_material_size);
	return true;
	}

	bool Keymaster0Engine::ImportKey(keymaster_key_format_t key_format,
	const KeymasterKeyBlob& to_import,
	KeymasterKeyBlob* imported_key) const {
	assert(imported_key);
	if (key_format != KM_KEY_FORMAT_PKCS8)
	return false;

	uint8_t* key_blob = 0;
	if (keymaster0_device_->import_keypair(keymaster0_device_, to_import.key_material,
	to_import.key_material_size, &key_blob,
	&imported_key->key_material_size) < 0) {
	ALOGW("Error importing keypair with keymaster0 device");
	return false;
	}
	unique_ptr<uint8_t, Malloc_Delete> key_blob_deleter(key_blob);
	imported_key->key_material = dup_buffer(key_blob, imported_key->key_material_size);
	return true;
	}

	static keymaster_key_blob_t* duplicate_blob(const uint8_t* key_data, size_t key_data_size) {
	unique_ptr<uint8_t[]> key_material_copy(new uint8_t[key_data_size]);
	if (!key_material_copy)
	return nullptr;

	memcpy(key_material_copy.get(), key_data, key_data_size);
	unique_ptr<keymaster_key_blob_t> blob_copy(new keymaster_key_blob_t);
	blob_copy->key_material_size = key_data_size;
	blob_copy->key_material = key_material_copy.release();
	return blob_copy.release();
	}

	inline keymaster_key_blob_t* duplicate_blob(const keymaster_key_blob_t& blob) {
	return duplicate_blob(blob.key_material, blob.key_material_size);
	}

	RSA* Keymaster0Engine::BlobToRsaKey(const KeymasterKeyBlob& blob) const {
	// Create new RSA key (with engine methods) and insert blob
	unique_ptr<RSA, RSA_Delete> rsa(RSA_new_method(engine_));
	if (!rsa)
	return nullptr;

	keymaster_key_blob_t* blob_copy = duplicate_blob(blob);
	if (!blob_copy->key_material \|\| !RSA_set_ex_data(rsa.get(), rsa_index_, blob_copy))
	return nullptr;

	// Copy public key into new RSA key
	unique_ptr<EVP_PKEY, EVP_PKEY_Delete> pkey(GetKeymaster0PublicKey(blob));
	if (!pkey)
	return nullptr;
	unique_ptr<RSA, RSA_Delete> public_rsa(EVP_PKEY_get1_RSA(pkey.get()));
	if (!public_rsa)
	return nullptr;
	rsa->n = BN_dup(public_rsa->n);
	rsa->e = BN_dup(public_rsa->e);
	if (!rsa->n \|\| !rsa->e)
	return nullptr;

	return rsa.release();
	}

	EC_KEY* Keymaster0Engine::BlobToEcKey(const KeymasterKeyBlob& blob) const {
	// Create new EC key (with engine methods) and insert blob
	unique_ptr<EC_KEY, EC_Delete> ec_key(EC_KEY_new_method(engine_));
	if (!ec_key)
	return nullptr;

	keymaster_key_blob_t* blob_copy = duplicate_blob(blob);
	if (!blob_copy->key_material \|\| !EC_KEY_set_ex_data(ec_key.get(), ec_key_index_, blob_copy))
	return nullptr;

	// Copy public key into new EC key
	unique_ptr<EVP_PKEY, EVP_PKEY_Delete> pkey(GetKeymaster0PublicKey(blob));
	if (!pkey)
	return nullptr;

	unique_ptr<EC_KEY, EC_Delete> public_ec_key(EVP_PKEY_get1_EC_KEY(pkey.get()));
	if (!public_ec_key)
	return nullptr;

	if (!EC_KEY_set_group(ec_key.get(), EC_KEY_get0_group(public_ec_key.get())) \|\|
	!EC_KEY_set_public_key(ec_key.get(), EC_KEY_get0_public_key(public_ec_key.get())))
	return nullptr;

	return ec_key.release();
	}

	const keymaster_key_blob_t* Keymaster0Engine::RsaKeyToBlob(const RSA* rsa) const {
	return reinterpret_cast<keymaster_key_blob_t*>(RSA_get_ex_data(rsa, rsa_index_));
	}

	const keymaster_key_blob_t* Keymaster0Engine::EcKeyToBlob(const EC_KEY* ec_key) const {
	return reinterpret_cast<keymaster_key_blob_t*>(EC_KEY_get_ex_data(ec_key, ec_key_index_));
	}

	/* static */
	int Keymaster0Engine::keyblob_dup(CRYPTO_EX_DATA* /* to /, const CRYPTO_EX_DATA /* from */,
	void** from_d, int /* index /, long / argl */,
	void* /* argp */) {
	keymaster_key_blob_t* blob = reinterpret_cast<keymaster_key_blob_t>(from_d);
	if (!blob)
	return 1;
	from_d = duplicate_blob(blob);
	if (*from_d)
	return 1;
	return 0;
	}

	/* static */
	void Keymaster0Engine::keyblob_free(void* /* parent /, void ptr, CRYPTO_EX_DATA* /* data */,
	int /* index/, long / argl /, void /* argp */) {
	keymaster_key_blob_t* blob = reinterpret_cast<keymaster_key_blob_t*>(ptr);
	if (blob) {
	delete[] blob->key_material;
	delete blob;
	}
	}

	/* static */
	int Keymaster0Engine::rsa_private_transform(RSA* rsa, uint8_t* out, const uint8_t* in, size_t len) {
	ALOGV("rsa_private_transform(%p, %p, %p, %u)", rsa, out, in, (unsigned)len);

	assert(instance_);
	return instance_->RsaPrivateTransform(rsa, out, in, len);
	}

	/* static */
	int Keymaster0Engine::ecdsa_sign(const uint8_t* digest, size_t digest_len, uint8_t* sig,
	unsigned int* sig_len, EC_KEY* ec_key) {
	ALOGV("ecdsa_sign(%p, %u, %p)", digest, (unsigned)digest_len, ec_key);
	assert(instance_);
	return instance_->EcdsaSign(digest, digest_len, sig, sig_len, ec_key);
	}

	bool Keymaster0Engine::Keymaster0Sign(const void* signing_params, const keymaster_key_blob_t& blob,
	const uint8_t* data, const size_t data_length,
	unique_ptr<uint8_t[], Malloc_Delete>* signature,
	size_t* signature_length) const {
	uint8_t* signed_data;
	int err = keymaster0_device_->sign_data(keymaster0_device_, signing_params, blob.key_material,
	blob.key_material_size, data, data_length, &signed_data,
	signature_length);
	if (err < 0) {
	ALOGE("Keymaster0 signing failed with error %d", err);
	return false;
	}

	signature->reset(signed_data);
	return true;
	}

	EVP_PKEY* Keymaster0Engine::GetKeymaster0PublicKey(const KeymasterKeyBlob& blob) const {
	uint8_t* pub_key_data;
	size_t pub_key_data_length;
	int err = keymaster0_device_->get_keypair_public(keymaster0_device_, blob.key_material,
	blob.key_material_size, &pub_key_data,
	&pub_key_data_length);
	if (err < 0) {
	ALOGE("Error %d extracting public key", err);
	return nullptr;
	}
	unique_ptr<uint8_t, Malloc_Delete> pub_key(pub_key_data);

	const uint8_t* p = pub_key_data;
	return d2i_PUBKEY(nullptr /* allocate new struct */, &p, pub_key_data_length);
	}

	int Keymaster0Engine::RsaPrivateTransform(RSA* rsa, uint8_t* out, const uint8_t* in,
	size_t len) const {
	const keymaster_key_blob_t* key_blob = RsaKeyToBlob(rsa);
	if (key_blob == NULL) {
	ALOGE("key had no key_blob!");
	return 0;
	}

	keymaster_rsa_sign_params_t sign_params = {DIGEST_NONE, PADDING_NONE};
	unique_ptr<uint8_t[], Malloc_Delete> signature;
	size_t signature_length;
	if (!Keymaster0Sign(&sign_params, *key_blob, in, len, &signature, &signature_length))
	return 0;
	Eraser eraser(signature.get(), signature_length);

	if (signature_length > len) {
	/* The result of the RSA operation can never be larger than the size of
	* the modulus so we assume that the result has extra zeros on the
	* left. This provides attackers with an oracle, but there's nothing
	* that we can do about it here. */
	memcpy(out, signature.get() + signature_length - len, len);
	} else if (signature_length < len) {
	/* If the keymaster0 implementation returns a short value we assume that
	* it's because it removed leading zeros from the left side. This is
	* bad because it provides attackers with an oracle but we cannot do
	* anything about a broken keymaster0 implementation here. */
	memset(out, 0, len);
	memcpy(out + len - signature_length, signature.get(), signature_length);
	} else {
	memcpy(out, signature.get(), len);
	}

	ALOGV("rsa=%p keystore_rsa_priv_dec successful", rsa);
	return 1;
	}

	int Keymaster0Engine::EcdsaSign(const uint8_t* digest, size_t digest_len, uint8_t* sig,
	unsigned int* sig_len, EC_KEY* ec_key) const {
	const keymaster_key_blob_t* key_blob = EcKeyToBlob(ec_key);
	if (key_blob == NULL) {
	ALOGE("key had no key_blob!");
	return 0;
	}

	keymaster_ec_sign_params_t sign_params = {DIGEST_NONE};
	unique_ptr<uint8_t[], Malloc_Delete> signature;
	size_t signature_length;
	if (!Keymaster0Sign(&sign_params, *key_blob, digest, digest_len, &signature, &signature_length))
	return 0;
	Eraser eraser(signature.get(), signature_length);

	if (signature_length == 0) {
	ALOGW("No valid signature returned");
	return 0;
	} else if (signature_length > ECDSA_size(ec_key)) {
	ALOGW("Signature is too large");
	return 0;
	} else {
	memcpy(sig, signature.get(), signature_length);
	*sig_len = signature_length;
	}

	ALOGV("ecdsa_sign(%p, %u, %p) => success", digest, (unsigned)digest_len, ec_key);
	return 1;
	}

	} // namespace keymaster