path: root/crypto/ext4crypt/Decrypt.cpp

/*
 * Copyright (C) 2016 The Team Win Recovery 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 "Decrypt.h"
#include "Ext4Crypt.h"

#include <map>
#include <string>

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/types.h>

#ifndef HAVE_LIBKEYUTILS
#include "key_control.h"
#else
#include <keyutils.h>
#endif

#ifdef HAVE_SYNTH_PWD_SUPPORT
#include "Weaver1.h"
#include "cutils/properties.h"

#include <openssl/sha.h>
#include <openssl/aes.h>
#include <openssl/evp.h>
#include <openssl/rand.h>

#include <dirent.h>
#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <sys/types.h>
#include <fstream>

#include <ext4_utils/ext4_crypt.h>

#include <keystore/IKeystoreService.h>
#include <binder/IPCThreadState.h>
#include <binder/IServiceManager.h>

#include <keystore/keystore.h>
#include <keystore/authorization_set.h>

#include <algorithm>
extern "C" {
#include "crypto_scrypt.h"
}
#else
#include "ext4_crypt.h"
#endif //ifdef HAVE_SYNTH_PWD_SUPPORT

#ifdef HAVE_GATEKEEPER1
#include <android/hardware/gatekeeper/1.0/IGatekeeper.h>
#else
#include <hardware/gatekeeper.h>
#endif
#include "HashPassword.h"

#include <android-base/file.h>

// Store main DE raw ref / policy
extern std::string de_raw_ref;
extern std::map<userid_t, std::string> s_de_key_raw_refs;
extern std::map<userid_t, std::string> s_ce_key_raw_refs;

static bool lookup_ref_key_internal(std::map<userid_t, std::string>& key_map, const char* policy, userid_t* user_id) {
    for (std::map<userid_t, std::string>::iterator it=key_map.begin(); it!=key_map.end(); ++it) {
        if (strncmp(it->second.c_str(), policy, it->second.size()) == 0) {
            *user_id = it->first;
            return true;
        }
    }
    return false;
}

extern "C" bool lookup_ref_key(const char* policy, char* policy_type) {
    userid_t user_id = 0;
    if (strncmp(de_raw_ref.c_str(), policy, de_raw_ref.size()) == 0) {
        strcpy(policy_type, "1DK");
        return true;
    }
    if (!lookup_ref_key_internal(s_de_key_raw_refs, policy, &user_id)) {
        if (!lookup_ref_key_internal(s_ce_key_raw_refs, policy, &user_id)) {
            return false;
		} else
		    sprintf(policy_type, "1CE%d", user_id);
    } else
        sprintf(policy_type, "1DE%d", user_id);
    return true;
}

extern "C" bool lookup_ref_tar(const char* policy_type, char* policy) {
    if (strncmp(policy_type, "1", 1) != 0) {
        printf("Unexpected version %c\n", policy_type[0]);
        return false;
    }
    const char* ptr = policy_type + 1; // skip past the version number
    if (strncmp(ptr, "DK", 2) == 0) {
        strncpy(policy, de_raw_ref.data(), de_raw_ref.size());
        return true;
    }
    userid_t user_id = atoi(ptr + 2);
    std::string raw_ref;
    if (*ptr == 'D') {
        if (lookup_key_ref(s_de_key_raw_refs, user_id, &raw_ref)) {
            strncpy(policy, raw_ref.data(), raw_ref.size());
        } else
            return false;
    } else if (*ptr == 'C') {
        if (lookup_key_ref(s_ce_key_raw_refs, user_id, &raw_ref)) {
            strncpy(policy, raw_ref.data(), raw_ref.size());
        } else
            return false;
    } else {
        printf("unknown policy type '%s'\n", policy_type);
        return false;
    }
    return true;
}

#ifndef HAVE_GATEKEEPER1
int gatekeeper_device_initialize(gatekeeper_device_t **dev) {
	int ret;
	const hw_module_t *mod;
	ret = hw_get_module_by_class(GATEKEEPER_HARDWARE_MODULE_ID, NULL, &mod);

	if (ret!=0) {
		printf("failed to get hw module\n");
		return ret;
	}

	ret = gatekeeper_open(mod, dev);

	if (ret!=0)
		printf("failed to open gatekeeper\n");
	return ret;
}
#endif //ifndef HAVE_GATEKEEPER1

bool Decrypt_DE() {
	if (!e4crypt_initialize_global_de()) { // this deals with the overarching device encryption
		printf("e4crypt_initialize_global_de returned fail\n");
		return false;
	}
	if (!e4crypt_init_user0()) {
		printf("e4crypt_init_user0 returned fail\n");
		return false;
	}
	return true;
}

#ifdef HAVE_SYNTH_PWD_SUPPORT
// Crappy functions for debugging, please ignore unless you need to debug
/*void output_hex(const std::string& in) {
	const char *buf = in.data();
	char hex[in.size() * 2 + 1];
	unsigned int index;
	for (index = 0; index < in.size(); index++)
		sprintf(&hex[2 * index], "%02X", buf[index]);
	printf("%s", hex);
}

void output_hex(const char* buf, const int size) {
	char hex[size * 2 + 1];
	int index;
	for (index = 0; index < size; index++)
		sprintf(&hex[2 * index], "%02X", buf[index]);
	printf("%s", hex);
}

void output_hex(const unsigned char* buf, const int size) {
	char hex[size * 2 + 1];
	int index;
	for (index = 0; index < size; index++)
		sprintf(&hex[2 * index], "%02X", buf[index]);
	printf("%s", hex);
}

void output_hex(std::vector<uint8_t>* vec) {
	char hex[3];
	unsigned int index;
	for (index = 0; index < vec->size(); index++) {
		sprintf(&hex[0], "%02X", vec->at(index));
		printf("%s", hex);
	}
}*/

/* An alternative is to use:
 * sqlite3 /data/system/locksettings.db "SELECT value FROM locksettings WHERE name='sp-handle' AND user=0;"
 * but we really don't want to include the 1.1MB libsqlite in TWRP. We scan the spblob folder for the
 * password data file (*.pwd) and get the handle from the filename instead. This is a replacement for
 * https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/services/core/java/com/android/server/locksettings/LockSettingsService.java#2017
 * We never use this data as an actual long. We always use it as a string. */
bool Find_Handle(const std::string& spblob_path, std::string& handle_str) {
	DIR* dir = opendir(spblob_path.c_str());
	if (!dir) {
		printf("Error opening '%s'\n", spblob_path.c_str());
		return false;
	}

	struct dirent* de = 0;

	while ((de = readdir(dir)) != 0) {
		if (strcmp(de->d_name, ".") == 0 || strcmp(de->d_name, "..") == 0)
			continue;
		size_t len = strlen(de->d_name);
		if (len <= 4)
			continue;
		char* p = de->d_name;
		p += len - 4;
		if (strncmp(p, ".pwd", 4) == 0) {
			handle_str = de->d_name;
			handle_str = handle_str.substr(0, len - 4);
			//*handle = strtoull(handle_str.c_str(), 0 , 16);
			closedir(dir);
			return true;
		}
	}
	closedir(dir);
	return false;
}

// The password data is stored in big endian and has to be swapped on little endian ARM
template <class T>
void endianswap(T *objp) {
	unsigned char *memp = reinterpret_cast<unsigned char*>(objp);
	std::reverse(memp, memp + sizeof(T));
}

/* This is the structure of the data in the password data (*.pwd) file which the structure can be found
 * https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/services/core/java/com/android/server/locksettings/SyntheticPasswordManager.java#187 */
struct password_data_struct {
	int password_type;
	unsigned char scryptN;
	unsigned char scryptR;
	unsigned char scryptP;
	int salt_len;
	void* salt;
	int handle_len;
	void* password_handle;
};

/* C++ replacement for
 * https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/services/core/java/com/android/server/locksettings/SyntheticPasswordManager.java#764 */
bool Get_Password_Data(const std::string& spblob_path, const std::string& handle_str, password_data_struct *pwd) {
	std::string pwd_file = spblob_path + handle_str + ".pwd";
	std::string pwd_data;
	if (!android::base::ReadFileToString(pwd_file, &pwd_data)) {
		printf("Failed to read '%s'\n", pwd_file.c_str());
		return false;
	}
	//output_hex(pwd_data.data(), pwd_data.size());printf("\n");
	const int* intptr = (const int*)pwd_data.data();
	pwd->password_type = *intptr;
	endianswap(&pwd->password_type);
	//printf("password type %i\n", pwd->password_type); // 2 was PIN, 1 for pattern, 2 also for password, -1 for default password
	const unsigned char* byteptr = (const unsigned char*)pwd_data.data() + sizeof(int);
	pwd->scryptN = *byteptr;
	byteptr++;
	pwd->scryptR = *byteptr;
	byteptr++;
	pwd->scryptP = *byteptr;
	byteptr++;
	intptr = (const int*)byteptr;
	pwd->salt_len = *intptr;
	endianswap(&pwd->salt_len);
	if (pwd->salt_len != 0) {
		pwd->salt = malloc(pwd->salt_len);
		if (!pwd->salt) {
			printf("Get_Password_Data malloc salt\n");
			return false;
		}
		memcpy(pwd->salt, intptr + 1, pwd->salt_len);
	} else {
		printf("Get_Password_Data salt_len is 0\n");
		return false;
	}
	return true;
}

/* C++ replacement for
 * https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/services/core/java/com/android/server/locksettings/SyntheticPasswordManager.java#765
 * called here
 * https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/services/core/java/com/android/server/locksettings/SyntheticPasswordManager.java#1050 */
bool Get_Password_Token(const password_data_struct *pwd, const std::string& Password, unsigned char* password_token) {
	if (!password_token) {
		printf("password_token is null\n");
		return false;
	}
	unsigned int N = 1 << pwd->scryptN;
	unsigned int r = 1 << pwd->scryptR;
	unsigned int p = 1 << pwd->scryptP;
	//printf("N %i r %i p %i\n", N, r, p);
	int ret = crypto_scrypt(reinterpret_cast<const uint8_t*>(Password.data()), Password.size(),
                          reinterpret_cast<const uint8_t*>(pwd->salt), pwd->salt_len,
                          N, r, p,
                          password_token, 32);
	if (ret != 0) {
		printf("scrypt error\n");
		return false;
	}
	return true;
}

// Data structure for the *.weaver file, see Get_Weaver_Data below
struct weaver_data_struct {
	unsigned char version;
	int slot;
};

/* C++ replacement for
 * https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/services/core/java/com/android/server/locksettings/SyntheticPasswordManager.java#501
 * called here
 * https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/services/core/java/com/android/server/locksettings/SyntheticPasswordManager.java#768 */
bool Get_Weaver_Data(const std::string& spblob_path, const std::string& handle_str, weaver_data_struct *wd) {
	std::string weaver_file = spblob_path + handle_str + ".weaver";
	std::string weaver_data;
	if (!android::base::ReadFileToString(weaver_file, &weaver_data)) {
		printf("Failed to read '%s'\n", weaver_file.c_str());
		return false;
	}
	//output_hex(weaver_data.data(), weaver_data.size());printf("\n");
	const unsigned char* byteptr = (const unsigned char*)weaver_data.data();
	wd->version = *byteptr;
	//printf("weaver version %i\n", wd->version);
	const int* intptr = (const int*)weaver_data.data() + sizeof(unsigned char);
	wd->slot = *intptr;
	//endianswap(&wd->slot); not needed
	//printf("weaver slot %i\n", wd->slot);
	return true;
}

namespace android {

// On Android 8.0 for some reason init can't seem to completely stop keystore
// so we have to kill it too if it doesn't die on its own.
static void kill_keystore() {
    DIR* dir = opendir("/proc");
    if (dir) {
        struct dirent* de = 0;

        while ((de = readdir(dir)) != 0) {
            if (strcmp(de->d_name, ".") == 0 || strcmp(de->d_name, "..") == 0)
                continue;

            int pid = -1;
            int ret = sscanf(de->d_name, "%d", &pid);

            if (ret == 1) {
                char cmdpath[PATH_MAX];
                sprintf(cmdpath, "/proc/%d/cmdline", pid);

                FILE* file = fopen(cmdpath, "r");
                size_t task_size = PATH_MAX;
                char task[PATH_MAX];
                char* p = task;
                if (getline(&p, &task_size, file) > 0) {
                    if (strstr(task, "keystore") != 0) {
                        printf("keystore pid %d found, sending kill.\n", pid);
                        kill(pid, SIGINT);
                        usleep(5000);
                        kill(pid, SIGKILL);
                    }
                }
                fclose(file);
            }
        }
        closedir(dir);
    }
}

// The keystore holds a file open on /data so we have to stop / kill it
// if we want to be able to unmount /data for things like formatting.
static void stop_keystore() {
    printf("Stopping keystore...\n");
    property_set("ctl.stop", "keystore");
    usleep(5000);
    kill_keystore();
}

/* These next 2 functions try to get the keystore service 50 times because
 * the keystore is not always ready when TWRP boots */
sp<IBinder> getKeystoreBinder() {
	sp<IServiceManager> sm = defaultServiceManager();
    return sm->getService(String16("android.security.keystore"));
}

sp<IBinder> getKeystoreBinderRetry() {
	printf("Starting keystore...\n");
    property_set("ctl.start", "keystore");
	int retry_count = 50;
	sp<IBinder> binder = getKeystoreBinder();
	while (binder == NULL && retry_count) {
		printf("Waiting for keystore service... %i\n", retry_count--);
		sleep(1);
		binder = getKeystoreBinder();
	}
	return binder;
}

namespace keystore {

#define SYNTHETIC_PASSWORD_VERSION 1
#define SYNTHETIC_PASSWORD_PASSWORD_BASED 0
#define SYNTHETIC_PASSWORD_KEY_PREFIX "USRSKEY_synthetic_password_"

/* The keystore alias subid is sometimes the same as the handle, but not always.
 * In the case of handle 0c5303fd2010fe29, the alias subid used c5303fd2010fe29
 * without the leading 0. We could try to parse the data from a previous
 * keystore request, but I think this is an easier solution because there
 * is little to no documentation on the format of data we get back from
 * the keystore in this instance. We also want to copy everything to a temp
 * folder so that any key upgrades that might take place do not actually
 * upgrade the keys on the data partition. We rename all 1000 uid files to 0
 * to pass the keystore permission checks. */
bool Find_Keystore_Alias_SubID_And_Prep_Files(const userid_t user_id, std::string& keystoreid) {
	char path_c[PATH_MAX];
	sprintf(path_c, "/data/misc/keystore/user_%d", user_id);
	char user_dir[PATH_MAX];
	sprintf(user_dir, "user_%d", user_id);
	std::string source_path = "/data/misc/keystore/";
	source_path += user_dir;

	mkdir("/tmp/misc", 0755);
	mkdir("/tmp/misc/keystore", 0755);
	std::string destination_path = "/tmp/misc/keystore/";
	destination_path += user_dir;
	if (mkdir(destination_path.c_str(), 0755) && errno != EEXIST) {
		printf("failed to mkdir '%s' %s\n", destination_path.c_str(), strerror(errno));
		return false;
	}
	destination_path += "/";

	DIR* dir = opendir(source_path.c_str());
	if (!dir) {
		printf("Error opening '%s'\n", source_path.c_str());
		return false;
	}
	source_path += "/";

	struct dirent* de = 0;
	size_t prefix_len = strlen(SYNTHETIC_PASSWORD_KEY_PREFIX);
	bool found_subid = false;

	while ((de = readdir(dir)) != 0) {
		if (strcmp(de->d_name, ".") == 0 || strcmp(de->d_name, "..") == 0)
			continue;
		if (!found_subid) {
			size_t len = strlen(de->d_name);
			if (len <= prefix_len)
				continue;
			if (!strstr(de->d_name, SYNTHETIC_PASSWORD_KEY_PREFIX))
				continue;
			std::string file = de->d_name;
			std::size_t found = file.find_last_of("_");
			if (found != std::string::npos) {
				keystoreid = file.substr(found + 1);
				printf("keystoreid: '%s'\n", keystoreid.c_str());
				found_subid = true;
			}
		}
		std::string src = source_path;
		src += de->d_name;
		std::ifstream srcif(src.c_str(), std::ios::binary);
		std::string dst = destination_path;
		dst += de->d_name;
		std::size_t source_uid = dst.find("1000");
		if (source_uid != std::string::npos)
			dst.replace(source_uid, 4, "0");
		std::ofstream dstof(dst.c_str(), std::ios::binary);
		printf("copying '%s' to '%s'\n", src.c_str(), dst.c_str());
		dstof << srcif.rdbuf();
		srcif.close();
		dstof.close();
	}
	closedir(dir);
	return found_subid;
}

/* C++ replacement for function of the same name
 * https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/services/core/java/com/android/server/locksettings/SyntheticPasswordManager.java#867
 * returning an empty string indicates an error */
std::string unwrapSyntheticPasswordBlob(const std::string& spblob_path, const std::string& handle_str, const userid_t user_id, const void* application_id, const size_t application_id_size) {
	std::string disk_decryption_secret_key = "";

	std::string keystore_alias_subid;
	if (!Find_Keystore_Alias_SubID_And_Prep_Files(user_id, keystore_alias_subid)) {
		printf("failed to scan keystore alias subid and prep keystore files\n");
		return disk_decryption_secret_key;
	}

	// First get the keystore service
    sp<IBinder> binder = getKeystoreBinderRetry();
	sp<IKeystoreService> service = interface_cast<IKeystoreService>(binder);
	if (service == NULL) {
		printf("error: could not connect to keystore service\n");
		return disk_decryption_secret_key;
	}

	// Read the data from the .spblob file per: https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/services/core/java/com/android/server/locksettings/SyntheticPasswordManager.java#869
	std::string spblob_file = spblob_path + handle_str + ".spblob";
	std::string spblob_data;
	if (!android::base::ReadFileToString(spblob_file, &spblob_data)) {
		printf("Failed to read '%s'\n", spblob_file.c_str());
		return disk_decryption_secret_key;
	}
	const unsigned char* byteptr = (const unsigned char*)spblob_data.data();
	if (*byteptr != SYNTHETIC_PASSWORD_VERSION) {
		printf("SYNTHETIC_PASSWORD_VERSION does not match\n");
		return disk_decryption_secret_key;
	}
	byteptr++;
	if (*byteptr != SYNTHETIC_PASSWORD_PASSWORD_BASED) {
		printf("spblob data is not SYNTHETIC_PASSWORD_PASSWORD_BASED\n");
		return disk_decryption_secret_key;
	}
	byteptr++; // Now we're pointing to the blob data itself
	/* We're now going to handle decryptSPBlob: https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/services/core/java/com/android/server/locksettings/SyntheticPasswordCrypto.java#115
	 * Called from https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/services/core/java/com/android/server/locksettings/SyntheticPasswordManager.java#879
	 * This small function ends up being quite a headache. The call to get data from the keystore basically is not needed in TWRP at this time.
	 * The keystore data seems to be the serialized data from an entire class in Java. Specifically I think it represents:
	 * https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/keystore/java/android/security/keystore/AndroidKeyStoreCipherSpiBase.java
	 * or perhaps
	 * https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/keystore/java/android/security/keystore/AndroidKeyStoreAuthenticatedAESCipherSpi.java
	 * but the only things we "need" from this keystore are a user ID and the keyAlias which ends up being USRSKEY_synthetic_password_{handle_str}
	 * the latter of which we already have. We may need to figure out how to get the user ID if we ever support decrypting mulitple users.
	 * There are 2 calls to a Java decrypt funcion that is overloaded. These 2 calls go in completely different directions despite the seemingly
	 * similar use of decrypt() and decrypt parameters. To figure out where things were going, I added logging to:
	 * https://android.googlesource.com/platform/libcore/+/android-8.0.0_r23/ojluni/src/main/java/javax/crypto/Cipher.java#2575
	 * Logger.global.severe("Cipher tryCombinations " + prov.getName() + " - " + prov.getInfo());
	 * To make logging work in libcore, import java.util.logging.Logger; and either set a better logging level or modify the framework to log everything
	 * regardless of logging level. This will give you some strings that you can grep for and find the actual crypto provider in use. In our case there were
	 * 2 different providers in use. The first stage to get the intermediate key used:
	 * https://android.googlesource.com/platform/external/conscrypt/+/android-8.0.0_r23/common/src/main/java/org/conscrypt/OpenSSLProvider.java
	 * which is a pretty straight-forward OpenSSL implementation of AES/GCM/NoPadding. */
	// First we personalize as seen https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/services/core/java/com/android/server/locksettings/SyntheticPasswordCrypto.java#102
	void* personalized_application_id = PersonalizedHashBinary(PERSONALISATION_APPLICATION_ID, (const char*)application_id, application_id_size);
	if (!personalized_application_id) {
		printf("malloc personalized_application_id\n");
		return disk_decryption_secret_key;
	}
	//printf("personalized application id: "); output_hex((unsigned char*)personalized_application_id, SHA512_DIGEST_LENGTH); printf("\n");
	// Now we'll decrypt using openssl AES/GCM/NoPadding
	OpenSSL_add_all_ciphers();
	int actual_size=0, final_size=0;
    EVP_CIPHER_CTX *d_ctx = EVP_CIPHER_CTX_new();
    const unsigned char* iv = (const unsigned char*)byteptr; // The IV is the first 12 bytes of the spblob
    //printf("iv: "); output_hex((const unsigned char*)iv, 12); printf("\n");
    const unsigned char* cipher_text = (const unsigned char*)byteptr + 12; // The cipher text comes immediately after the IV
    //printf("cipher_text: "); output_hex((const unsigned char*)cipher_text, spblob_data.size() - 2 - 12); printf("\n");
    const unsigned char* key = (const unsigned char*)personalized_application_id; // The key is the now personalized copy of the application ID
    //printf("key: "); output_hex((const unsigned char*)key, 32); printf("\n");
    EVP_DecryptInit(d_ctx, EVP_aes_256_gcm(), key, iv);
    std::vector<unsigned char> intermediate_key;
    intermediate_key.resize(spblob_data.size() - 2 - 12, '\0');
    EVP_DecryptUpdate(d_ctx, &intermediate_key[0], &actual_size, cipher_text, spblob_data.size() - 2 - 12);
    unsigned char tag[AES_BLOCK_SIZE];
    EVP_CIPHER_CTX_ctrl(d_ctx, EVP_CTRL_GCM_SET_TAG, 16, tag);
    EVP_DecryptFinal_ex(d_ctx, &intermediate_key[actual_size], &final_size);
    EVP_CIPHER_CTX_free(d_ctx);
    free(personalized_application_id);
    //printf("spblob_data size: %lu actual_size %i, final_size: %i\n", spblob_data.size(), actual_size, final_size);
    intermediate_key.resize(actual_size + final_size - 16, '\0');// not sure why we have to trim the size by 16 as I don't see where this is done in Java side
    //printf("intermediate key: "); output_hex((const unsigned char*)intermediate_key.data(), intermediate_key.size()); printf("\n");

	int32_t ret;

	/* We only need a keyAlias which is USRSKEY_synthetic_password_b6f71045af7bd042 which we find and a uid which is -1 or 1000, I forget which
	 * as the key data will be read again by the begin function later via the keystore.
	 * The data is in a hidl_vec format which consists of a type and a value. */
	/*::keystore::hidl_vec<uint8_t> data;
	std::string keystoreid = SYNTHETIC_PASSWORD_KEY_PREFIX;
	keystoreid += handle_str;

	ret = service->get(String16(keystoreid.c_str()), user_id, &data);
	if (ret < 0) {
		printf("Could not connect to keystore service %i\n", ret);
		return disk_decryption_secret_key;
	} else if (ret != 1 /*android::keystore::ResponseCode::NO_ERROR*//*) {
		printf("keystore error: (%d)\n", /*responses[ret],*//* ret);
		return disk_decryption_secret_key;
	} else {
		printf("keystore returned: "); output_hex(&data[0], data.size()); printf("\n");
	}*/

	// Now we'll break up the intermediate key into the IV (first 12 bytes) and the cipher text (the rest of it).
	std::vector<unsigned char> nonce = intermediate_key;
	nonce.resize(12);
	intermediate_key.erase (intermediate_key.begin(),intermediate_key.begin()+12);
	//printf("nonce: "); output_hex((const unsigned char*)nonce.data(), nonce.size()); printf("\n");
	//printf("cipher text: "); output_hex((const unsigned char*)intermediate_key.data(), intermediate_key.size()); printf("\n");

	/* Now we will begin the second decrypt call found in
	 * https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/services/core/java/com/android/server/locksettings/SyntheticPasswordCrypto.java#122
	 * This time we will use https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/keystore/java/android/security/keystore/AndroidKeyStoreCipherSpiBase.java
	 * and https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/keystore/java/android/security/keystore/AndroidKeyStoreAuthenticatedAESCipherSpi.java
	 * First we set some algorithm parameters as seen in two places:
	 * https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/keystore/java/android/security/keystore/AndroidKeyStoreAuthenticatedAESCipherSpi.java#297
	 * https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/keystore/java/android/security/keystore/AndroidKeyStoreAuthenticatedAESCipherSpi.java#216 */
	size_t maclen = 128;
	::keystore::AuthorizationSetBuilder begin_params;
	begin_params.Authorization(::keystore::TAG_ALGORITHM, ::keystore::Algorithm::AES);
	begin_params.Authorization(::keystore::TAG_BLOCK_MODE, ::keystore::BlockMode::GCM);
    begin_params.Padding(::keystore::PaddingMode::NONE);
    begin_params.Authorization(::keystore::TAG_NONCE, nonce);
    begin_params.Authorization(::keystore::TAG_MAC_LENGTH, maclen);
	//keymasterArgs.addEnum(KeymasterDefs.KM_TAG_ALGORITHM, KeymasterDefs.KM_ALGORITHM_AES);
	//keymasterArgs.addEnum(KeymasterDefs.KM_TAG_BLOCK_MODE, mKeymasterBlockMode);
	//keymasterArgs.addEnum(KeymasterDefs.KM_TAG_PADDING, mKeymasterPadding);
	//keymasterArgs.addUnsignedInt(KeymasterDefs.KM_TAG_MAC_LENGTH, mTagLengthBits);
	::keystore::hidl_vec<uint8_t> entropy; // No entropy is needed for decrypt
	entropy.resize(0);
	std::string keystore_alias = SYNTHETIC_PASSWORD_KEY_PREFIX;
	keystore_alias += keystore_alias_subid;
	String16 keystore_alias16(keystore_alias.c_str());
	::keystore::KeyPurpose purpose = ::keystore::KeyPurpose::DECRYPT;
	OperationResult begin_result;
	// These parameters are mostly driven by the cipher.init call https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/services/core/java/com/android/server/locksettings/SyntheticPasswordCrypto.java#63
	service->begin(binder, keystore_alias16, purpose, true, begin_params.hidl_data(), entropy, -1, &begin_result);
	ret = begin_result.resultCode;
	if (ret != 1 /*android::keystore::ResponseCode::NO_ERROR*/) {
		printf("keystore begin error: (%d)\n", /*responses[ret],*/ ret);
		return disk_decryption_secret_key;
	} else {
		//printf("keystore begin operation successful\n");
	}
	::keystore::hidl_vec<::keystore::KeyParameter> empty_params;
	empty_params.resize(0);
	OperationResult update_result;
	// The cipher.doFinal call triggers an update to the keystore followed by a finish https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/services/core/java/com/android/server/locksettings/SyntheticPasswordCrypto.java#64
	// See also https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/keystore/java/android/security/keystore/KeyStoreCryptoOperationChunkedStreamer.java#208
	service->update(begin_result.token, empty_params, intermediate_key, &update_result);
	ret = update_result.resultCode;
	if (ret != 1 /*android::keystore::ResponseCode::NO_ERROR*/) {
		printf("keystore update error: (%d)\n", /*responses[ret],*/ ret);
		return disk_decryption_secret_key;
	} else {
		//printf("keystore update operation successful\n");
		//printf("keystore update returned: "); output_hex(&update_result.data[0], update_result.data.size()); printf("\n"); // this ends up being the synthetic password
	}
	// We must use the data in update_data.data before we call finish below or the data will be gone
	// The payload data from the keystore update is further personalized at https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/services/core/java/com/android/server/locksettings/SyntheticPasswordManager.java#153
	// We now have the disk decryption key!
	disk_decryption_secret_key = PersonalizedHash(PERSONALIZATION_FBE_KEY, (const char*)&update_result.data[0], update_result.data.size());
	//printf("disk_decryption_secret_key: '%s'\n", disk_decryption_secret_key.c_str());
	::keystore::hidl_vec<uint8_t> signature;
	OperationResult finish_result;
	service->finish(begin_result.token, empty_params, signature, entropy, &finish_result);
	ret = finish_result.resultCode;
	if (ret != 1 /*android::keystore::ResponseCode::NO_ERROR*/) {
		printf("keystore finish error: (%d)\n", /*responses[ret],*/ ret);
		return disk_decryption_secret_key;
	} else {
		//printf("keystore finish operation successful\n");
	}
	stop_keystore();
	return disk_decryption_secret_key;
}

}}

#define PASSWORD_TOKEN_SIZE 32

bool Free_Return(bool retval, void* weaver_key, void* pwd_salt) {
	if (weaver_key)
		free(weaver_key);
	if (pwd_salt)
		free(pwd_salt);
	return retval;
}

/* Decrypt_User_Synth_Pass is the TWRP C++ equivalent to spBasedDoVerifyCredential
 * https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/services/core/java/com/android/server/locksettings/LockSettingsService.java#1998 */
bool Decrypt_User_Synth_Pass(const userid_t user_id, const std::string& Password) {
	bool retval = false;
	void* weaver_key = NULL;
	password_data_struct pwd;
	pwd.salt = NULL;

	std::string secret; // this will be the disk decryption key that is sent to vold
	std::string token = "!"; // there is no token used for this kind of decrypt, key escrow is handled by weaver
	int flags = FLAG_STORAGE_DE;
    if (user_id == 0)
		flags = FLAG_STORAGE_DE;
	else
		flags = FLAG_STORAGE_CE;
	char spblob_path_char[PATH_MAX];
	sprintf(spblob_path_char, "/data/system_de/%d/spblob/", user_id);
	std::string spblob_path = spblob_path_char;
	long handle = 0;
	std::string handle_str;
	// Get the handle: https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/services/core/java/com/android/server/locksettings/LockSettingsService.java#2017
	if (!Find_Handle(spblob_path, handle_str)) {
		printf("Error getting handle\n");
		return Free_Return(retval, weaver_key, pwd.salt);
	}
	printf("Handle is '%s'\n", handle_str.c_str());
	// Now we begin driving unwrapPasswordBasedSyntheticPassword from: https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/services/core/java/com/android/server/locksettings/SyntheticPasswordManager.java#758
	// First we read the password data which contains scrypt parameters
	if (!Get_Password_Data(spblob_path, handle_str, &pwd)) {
		printf("Failed to Get_Password_Data\n");
		return Free_Return(retval, weaver_key, pwd.salt);
	}
	//printf("pwd N %i R %i P %i salt ", pwd.scryptN, pwd.scryptR, pwd.scryptP); output_hex((char*)pwd.salt, pwd.salt_len); printf("\n");
	unsigned char password_token[PASSWORD_TOKEN_SIZE];
	//printf("Password: '%s'\n", Password.c_str());
	// The password token is the password scrypted with the parameters from the password data file
	if (!Get_Password_Token(&pwd, Password, &password_token[0])) {
		printf("Failed to Get_Password_Token\n");
		return Free_Return(retval, weaver_key, pwd.salt);
	}
	//output_hex(&password_token[0], PASSWORD_TOKEN_SIZE);printf("\n");
	// BEGIN PIXEL 2 WEAVER
	// Get the weaver data from the .weaver file which tells us which slot to use when we ask weaver for the escrowed key
	// https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/services/core/java/com/android/server/locksettings/SyntheticPasswordManager.java#768
	weaver_data_struct wd;
	if (!Get_Weaver_Data(spblob_path, handle_str, &wd)) {
		printf("Failed to get weaver data\n");
		// Fail over to gatekeeper path for Pixel 1???
		return Free_Return(retval, weaver_key, pwd.salt);
	}
	// The weaver key is the the password token prefixed with "weaver-key" padded to 128 with nulls with the password token appended then SHA512
	// https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/services/core/java/com/android/server/locksettings/SyntheticPasswordManager.java#1059
	weaver_key = PersonalizedHashBinary(PERSONALISATION_WEAVER_KEY, (char*)&password_token[0], PASSWORD_TOKEN_SIZE);
	if (!weaver_key) {
		printf("malloc error getting weaver_key\n");
		return Free_Return(retval, weaver_key, pwd.salt);
	}
	// Now we start driving weaverVerify: https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/services/core/java/com/android/server/locksettings/SyntheticPasswordManager.java#343
	// Called from https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/services/core/java/com/android/server/locksettings/SyntheticPasswordManager.java#776
	android::vold::Weaver weaver;
    if (!weaver) {
		printf("Failed to get weaver service\n");
		return Free_Return(retval, weaver_key, pwd.salt);
	}
	// Get the key size from weaver service
	uint32_t weaver_key_size = 0;
	if (!weaver.GetKeySize(&weaver_key_size)) {
		printf("Failed to get weaver key size\n");
		return Free_Return(retval, weaver_key, pwd.salt);
	} else {
		//printf("weaver key size is %u\n", weaver_key_size);
	}
	//printf("weaver key: "); output_hex((unsigned char*)weaver_key, weaver_key_size); printf("\n");
	// Send the slot from the .weaver file, the computed weaver key, and get the escrowed key data
	std::vector<uint8_t> weaver_payload;
	// TODO: we should return more information about the status including time delays before the next retry
	if (!weaver.WeaverVerify(wd.slot, weaver_key, &weaver_payload)) {
		printf("failed to weaver verify\n");
		return Free_Return(retval, weaver_key, pwd.salt);
	}
	//printf("weaver payload: "); output_hex(&weaver_payload); printf("\n");
	// Done with weaverVerify
	// Now we will compute the application ID
	// https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/services/core/java/com/android/server/locksettings/SyntheticPasswordManager.java#964
	// Called from https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/services/core/java/com/android/server/locksettings/SyntheticPasswordManager.java#780
	// The escrowed weaver key data is prefixed with "weaver-pwd" padded to 128 with nulls with the weaver payload appended then SHA512
	void* weaver_secret = PersonalizedHashBinary(PERSONALISATION_WEAVER_PASSWORD, (const char*)weaver_payload.data(), weaver_payload.size());
	//printf("weaver secret: "); output_hex((unsigned char*)weaver_secret, SHA512_DIGEST_LENGTH); printf("\n");
	// The application ID is the password token and weaver secret appended to each other
	char application_id[PASSWORD_TOKEN_SIZE + SHA512_DIGEST_LENGTH];
	memcpy((void*)&application_id[0], (void*)&password_token[0], PASSWORD_TOKEN_SIZE);
	memcpy((void*)&application_id[PASSWORD_TOKEN_SIZE], weaver_secret, SHA512_DIGEST_LENGTH);
	//printf("application ID: "); output_hex((unsigned char*)application_id, PASSWORD_TOKEN_SIZE + SHA512_DIGEST_LENGTH); printf("\n");
	// END PIXEL 2 WEAVER
	// Now we will handle https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/services/core/java/com/android/server/locksettings/SyntheticPasswordManager.java#816
	// Plus we will include the last bit that computes the disk decrypt key found in:
	// https://android.googlesource.com/platform/frameworks/base/+/android-8.0.0_r23/services/core/java/com/android/server/locksettings/SyntheticPasswordManager.java#153
	secret = android::keystore::unwrapSyntheticPasswordBlob(spblob_path, handle_str, user_id, (const void*)&application_id[0], PASSWORD_TOKEN_SIZE + SHA512_DIGEST_LENGTH);
	if (!secret.size()) {
		printf("failed to unwrapSyntheticPasswordBlob\n");
		return Free_Return(retval, weaver_key, pwd.salt);
	}
	if (!e4crypt_unlock_user_key(user_id, 0, token.c_str(), secret.c_str())) {
		printf("e4crypt_unlock_user_key returned fail\n");
		return Free_Return(retval, weaver_key, pwd.salt);
	}
	if (!e4crypt_prepare_user_storage(nullptr, user_id, 0, flags)) {
		printf("failed to e4crypt_prepare_user_storage\n");
		return Free_Return(retval, weaver_key, pwd.salt);
	}
	printf("Decrypted Successfully!\n");
	retval = true;
	return Free_Return(retval, weaver_key, pwd.salt);
}
#endif //HAVE_SYNTH_PWD_SUPPORT

int Get_Password_Type(const userid_t user_id, std::string& filename) {
	struct stat st;
	char spblob_path_char[PATH_MAX];
	sprintf(spblob_path_char, "/data/system_de/%d/spblob/", user_id);
	if (stat(spblob_path_char, &st) == 0) {
#ifdef HAVE_SYNTH_PWD_SUPPORT
		printf("Using synthetic password method\n");
		std::string spblob_path = spblob_path_char;
		std::string handle_str;
		if (!Find_Handle(spblob_path, handle_str)) {
			printf("Error getting handle\n");
			return 0;
		}
		printf("Handle is '%s'\n", handle_str.c_str());
		password_data_struct pwd;
		if (!Get_Password_Data(spblob_path, handle_str, &pwd)) {
			printf("Failed to Get_Password_Data\n");
			return 0;
		}
		if (pwd.password_type == 1) // In Android this means pattern
			return 2; // In TWRP this means pattern
		else if (pwd.password_type == 2) // In Android this means PIN or password
			return 1; // In TWRP this means PIN or password
		return 0; // We'll try the default password
#else
		printf("Synthetic password support not present in TWRP\n");
		return -1;
#endif
	}
	std::string path;
    if (user_id == 0) {
		path = "/data/system/";
	} else {
		char user_id_str[5];
		sprintf(user_id_str, "%i", user_id);
		path = "/data/system/users/";
		path += user_id_str;
		path += "/";
	}
	filename = path + "gatekeeper.password.key";
	if (stat(filename.c_str(), &st) == 0 && st.st_size > 0)
		return 1;
	filename = path + "gatekeeper.pattern.key";
	if (stat(filename.c_str(), &st) == 0 && st.st_size > 0)
		return 2;
	printf("Unable to locate gatekeeper password file '%s'\n", filename.c_str());
	filename = "";
	return 0;
}

bool Decrypt_User(const userid_t user_id, const std::string& Password) {
    uint8_t *auth_token;
    uint32_t auth_token_len;
    int ret;

    struct stat st;
    if (user_id > 9999) {
		printf("user_id is too big\n");
		return false;
	}
    std::string filename;
    bool Default_Password = (Password == "!");
    if (Get_Password_Type(user_id, filename) == 0 && !Default_Password) {
		printf("Unknown password type\n");
		return false;
	}
    int flags = FLAG_STORAGE_DE;
    if (user_id == 0)
		flags = FLAG_STORAGE_DE;
	else
		flags = FLAG_STORAGE_CE;
	if (Default_Password) {
		if (!e4crypt_unlock_user_key(user_id, 0, "!", "!")) {
			printf("e4crypt_unlock_user_key returned fail\n");
			return false;
		}
		if (!e4crypt_prepare_user_storage(nullptr, user_id, 0, flags)) {
			printf("failed to e4crypt_prepare_user_storage\n");
			return false;
		}
		printf("Decrypted Successfully!\n");
		return true;
	}
	if (stat("/data/system_de/0/spblob", &st) == 0) {
#ifdef HAVE_SYNTH_PWD_SUPPORT
		printf("Using synthetic password method\n");
		return Decrypt_User_Synth_Pass(user_id, Password);
#else
		printf("Synthetic password support not present in TWRP\n");
		return false;
#endif
	}
	printf("password filename is '%s'\n", filename.c_str());
	if (stat(filename.c_str(), &st) != 0) {
		printf("error stat'ing key file: %s\n", strerror(errno));
		return false;
	}
	std::string handle;
    if (!android::base::ReadFileToString(filename, &handle)) {
		printf("Failed to read '%s'\n", filename.c_str());
		return false;
	}
    bool should_reenroll;
#ifdef HAVE_GATEKEEPER1
	bool request_reenroll = false;
	android::sp<android::hardware::gatekeeper::V1_0::IGatekeeper> gk_device;
	gk_device = ::android::hardware::gatekeeper::V1_0::IGatekeeper::getService();
	if (gk_device == nullptr)
		return false;
	android::hardware::hidl_vec<uint8_t> curPwdHandle;
	curPwdHandle.setToExternal(const_cast<uint8_t *>((const uint8_t *)handle.c_str()), st.st_size);
	android::hardware::hidl_vec<uint8_t> enteredPwd;
	enteredPwd.setToExternal(const_cast<uint8_t *>((const uint8_t *)Password.c_str()), Password.size());

	android::hardware::Return<void> hwRet =
		gk_device->verify(user_id, 0 /* challange */,
						  curPwdHandle,
						  enteredPwd,
						  [&ret, &request_reenroll, &auth_token, &auth_token_len]
							(const android::hardware::gatekeeper::V1_0::GatekeeperResponse &rsp) {
								ret = static_cast<int>(rsp.code); // propagate errors
								if (rsp.code >= android::hardware::gatekeeper::V1_0::GatekeeperStatusCode::STATUS_OK) {
									auth_token = new uint8_t[rsp.data.size()];
									auth_token_len = rsp.data.size();
									memcpy(auth_token, rsp.data.data(), auth_token_len);
									request_reenroll = (rsp.code == android::hardware::gatekeeper::V1_0::GatekeeperStatusCode::STATUS_REENROLL);
									ret = 0; // all success states are reported as 0
								} else if (rsp.code == android::hardware::gatekeeper::V1_0::GatekeeperStatusCode::ERROR_RETRY_TIMEOUT && rsp.timeout > 0) {
									ret = rsp.timeout;
								}
							}
						 );
	if (!hwRet.isOk()) {
		return false;
	}
#else
	gatekeeper_device_t *gk_device;
	ret = gatekeeper_device_initialize(&gk_device);
    if (ret!=0)
		return false;
    ret = gk_device->verify(gk_device, user_id, 0, (const uint8_t *)handle.c_str(), st.st_size,
                (const uint8_t *)Password.c_str(), (uint32_t)Password.size(), &auth_token, &auth_token_len,
                &should_reenroll);
    if (ret !=0) {
		printf("failed to verify\n");
		return false;
	}
#endif
	char token_hex[(auth_token_len*2)+1];
	token_hex[(auth_token_len*2)] = 0;
	uint32_t i;
	for (i=0;i<auth_token_len;i++) {
		sprintf(&token_hex[2*i], "%02X", auth_token[i]);
	}
	// The secret is "Android FBE credential hash" plus appended 0x00 to reach 128 bytes then append the user's password then feed that to sha512sum
	std::string secret = HashPassword(Password);
	if (!e4crypt_unlock_user_key(user_id, 0, token_hex, secret.c_str())) {
		printf("e4crypt_unlock_user_key returned fail\n");
		return false;
	}
	if (!e4crypt_prepare_user_storage(nullptr, user_id, 0, flags)) {
		printf("failed to e4crypt_prepare_user_storage\n");
		return false;
	}
	printf("Decrypted Successfully!\n");
	return true;
}