#!/usr/bin/env python
# @ SingleSign.py
# Single signing script
#
# Copyright (c) 2020 - 2021, Intel Corporation. All rights reserved.<BR>
# SPDX-License-Identifier: BSD-2-Clause-Patent
#
##

import os
import sys
import re
import shutil
import subprocess

SIGNING_KEY = {
    # Key Id                                | Key File Name start |
    # =================================================================
    # KEY_ID_MASTER is used for signing Slimboot Key Hash Manifest \
    # container (KEYH Component)
    "KEY_ID_MASTER_RSA2048": "MasterTestKey_Priv_RSA2048.pem",
    "KEY_ID_MASTER_RSA3072": "MasterTestKey_Priv_RSA3072.pem",

    # KEY_ID_CFGDATA is used for signing external Config data blob)
    "KEY_ID_CFGDATA_RSA2048": "ConfigTestKey_Priv_RSA2048.pem",
    "KEY_ID_CFGDATA_RSA3072": "ConfigTestKey_Priv_RSA3072.pem",

    # KEY_ID_FIRMWAREUPDATE is used for signing capsule firmware update image)
    "KEY_ID_FIRMWAREUPDATE_RSA2048": "FirmwareUpdateTestKey_Priv_RSA2048.pem",
    "KEY_ID_FIRMWAREUPDATE_RSA3072": "FirmwareUpdateTestKey_Priv_RSA3072.pem",

    # KEY_ID_CONTAINER is used for signing container header with mono signature
    "KEY_ID_CONTAINER_RSA2048": "ContainerTestKey_Priv_RSA2048.pem",
    "KEY_ID_CONTAINER_RSA3072": "ContainerTestKey_Priv_RSA3072.pem",

    # CONTAINER_COMP1_KEY_ID is used for signing container components
    "KEY_ID_CONTAINER_COMP_RSA2048": "ContainerCompTestKey_Priv_RSA2048.pem",
    "KEY_ID_CONTAINER_COMP_RSA3072": "ContainerCompTestKey_Priv_RSA3072.pem",

    # KEY_ID_OS1_PUBLIC, KEY_ID_OS2_PUBLIC is used for referencing \
    # Boot OS public keys
    "KEY_ID_OS1_PUBLIC_RSA2048": "OS1_TestKey_Pub_RSA2048.pem",
    "KEY_ID_OS1_PUBLIC_RSA3072": "OS1_TestKey_Pub_RSA3072.pem",

    "KEY_ID_OS2_PUBLIC_RSA2048": "OS2_TestKey_Pub_RSA2048.pem",
    "KEY_ID_OS2_PUBLIC_RSA3072": "OS2_TestKey_Pub_RSA3072.pem",

    }

MESSAGE_SBL_KEY_DIR = """!!! PRE-REQUISITE: Path to SBL_KEY_DIR has.
to be set with SBL KEYS DIRECTORY !!! \n!!! Generate keys.
using GenerateKeys.py available in BootloaderCorePkg/Tools.
directory !!! \n !!! Run $python.
BootloaderCorePkg/Tools/GenerateKeys.py -k $PATH_TO_SBL_KEY_DIR !!!\n
!!! Set SBL_KEY_DIR environ with path to SBL KEYS DIR !!!\n"
!!! Windows $set SBL_KEY_DIR=$PATH_TO_SBL_KEY_DIR !!!\n
!!! Linux $export SBL_KEY_DIR=$PATH_TO_SBL_KEY_DIR !!!\n"""


def get_openssl_path():
    if os.name == 'nt':
        if 'OPENSSL_PATH' not in os.environ:
            openssl_dir = "C:\\Openssl\\bin\\"
            if os.path.exists(openssl_dir):
                os.environ['OPENSSL_PATH'] = openssl_dir
            else:
                os.environ['OPENSSL_PATH'] = "C:\\Openssl\\"
                if 'OPENSSL_CONF' not in os.environ:
                    openssl_cfg = "C:\\Openssl\\openssl.cfg"
                    if os.path.exists(openssl_cfg):
                        os.environ['OPENSSL_CONF'] = openssl_cfg
        openssl = os.path.join(
                    os.environ.get('OPENSSL_PATH', ''),
                    'openssl.exe')
    else:
        # Get openssl path for Linux cases
        openssl = shutil.which('openssl')

    return openssl


def run_process(arg_list, print_cmd=False, capture_out=False):
    sys.stdout.flush()
    if print_cmd:
        print(' '.join(arg_list))

    exc = None
    result = 0
    output = ''
    try:
        if capture_out:
            output = subprocess.check_output(arg_list).decode()
        else:
            result = subprocess.call(arg_list)
    except Exception as ex:
        result = 1
        exc = ex

    if result:
        if not print_cmd:
            print('Error in running process:\n  %s' % ' '.join(arg_list))
        if exc is None:
            sys.exit(1)
        else:
            raise exc

    return output


def check_file_pem_format(priv_key):
    # Check for file .pem format
    key_name = os.path.basename(priv_key)
    if os.path.splitext(key_name)[1] == ".pem":
        return True
    else:
        return False


def get_key_id(priv_key):
    # Extract base name if path is provided.
    key_name = os.path.basename(priv_key)
    # Check for KEY_ID in key naming.
    if key_name.startswith('KEY_ID'):
        return key_name
    else:
        return None


def get_sbl_key_dir():
    # Check Key store setting SBL_KEY_DIR path
    if 'SBL_KEY_DIR' not in os.environ:
        exception_string = "ERROR: SBL_KEY_DIR is not defined." \
                        " Set SBL_KEY_DIR with SBL Keys directory!!\n"
        raise Exception(exception_string + MESSAGE_SBL_KEY_DIR)

    sbl_key_dir = os.environ.get('SBL_KEY_DIR')
    if not os.path.exists(sbl_key_dir):
        exception_string = "ERROR:SBL_KEY_DIR set " + sbl_key_dir \
                        + " is not valid." \
                        " Set the correct SBL_KEY_DIR path !!\n" \
                        + MESSAGE_SBL_KEY_DIR
        raise Exception(exception_string)
    else:
        return sbl_key_dir


def get_key_from_store(in_key):

    # Check in_key is path to  key
    if os.path.exists(in_key):
        return in_key

    # Get Slimboot key dir path
    sbl_key_dir = get_sbl_key_dir()

    # Extract if in_key is key_id
    priv_key = get_key_id(in_key)
    if priv_key is not None:
        if (priv_key in SIGNING_KEY):
            # Generate key file name from key id
            priv_key_file = SIGNING_KEY[priv_key]
        else:
            exception_string = "KEY_ID" + priv_key + "is not found " \
                            "is not found in supported KEY IDs!!"
            raise Exception(exception_string)
    elif check_file_pem_format(in_key):
        # check if file name is provided in pem format
        priv_key_file = in_key
    else:
        priv_key_file = None
        raise Exception('key provided %s is not valid!' % in_key)

    # Create a file path
    # Join Key Dir and priv_key_file
    try:
        priv_key = os.path.join(sbl_key_dir, priv_key_file)
    except Exception:
        raise Exception('priv_key is not found %s!' % priv_key)

    # Check for priv_key construted based on KEY ID exists in specified path
    if not os.path.isfile(priv_key):
        exception_string = "!!! ERROR: Key file corresponding to" \
                        + in_key + "do not exist in Sbl key " \
                        "directory at" + sbl_key_dir + "!!! \n" \
                        + MESSAGE_SBL_KEY_DIR
        raise Exception(exception_string)

    return priv_key

#
# Sign an file using openssl
#
# priv_key   [Input]        Key Id or Path to Private key
# hash_type  [Input]        Signing hash
# sign_scheme[Input]        Sign/padding scheme
# in_file    [Input]        Input file to be signed
# out_file   [Input/Output] Signed data file
#


def single_sign_file(priv_key, hash_type, sign_scheme, in_file, out_file):

    _hash_type_string = {
        "SHA2_256": 'sha256',
        "SHA2_384": 'sha384',
        "SHA2_512": 'sha512',
    }

    _hash_digest_Size = {
        # Hash_string : Hash_Size
        "SHA2_256": 32,
        "SHA2_384": 48,
        "SHA2_512": 64,
        "SM3_256": 32,
    }

    _sign_scheme_string = {
        "RSA_PKCS1": 'pkcs1',
        "RSA_PSS": 'pss',
    }

    priv_key = get_key_from_store(priv_key)

    # Temporary files to store hash generated
    hash_file_tmp = out_file+'.hash.tmp'
    hash_file = out_file+'.hash'

    # Generate hash using openssl dgst in hex format
    cmdargs = [get_openssl_path(),
               'dgst',
               '-'+'%s' % _hash_type_string[hash_type],
               '-out', '%s' % hash_file_tmp, '%s' % in_file]
    run_process(cmdargs)

    # Extract hash form dgst command output and convert to ascii
    with open(hash_file_tmp, 'r') as fin:
        hashdata = fin.read()
    fin.close()

    try:
        hashdata = hashdata.rsplit('=', 1)[1].strip()
    except Exception:
        raise Exception('Hash Data not found for signing!')

    if len(hashdata) != (_hash_digest_Size[hash_type] * 2):
        raise Exception('Hash Data size do match with for hash type!')

    hashdata_bytes = bytearray.fromhex(hashdata)
    open(hash_file, 'wb').write(hashdata_bytes)

    print("Key used for Singing %s !!" % priv_key)

    # sign using Openssl pkeyutl
    cmdargs = [get_openssl_path(),
               'pkeyutl', '-sign', '-in', '%s' % hash_file,
               '-inkey', '%s' % priv_key, '-out',
               '%s' % out_file, '-pkeyopt',
               'digest:%s' % _hash_type_string[hash_type],
               '-pkeyopt', 'rsa_padding_mode:%s' %
               _sign_scheme_string[sign_scheme]]

    run_process(cmdargs)

    return

#
# Extract public key using openssl
#
# in_key        [Input]         Private key or public key in pem format
# pub_key_file  [Input/Output]  Public Key to a file
#
# return        keydata (mod, exp) in bin format
#


def single_sign_gen_pub_key(in_key, pub_key_file=None):

    in_key = get_key_from_store(in_key)

    # Expect key to be in PEM format
    is_prv_key = False
    cmdline = [get_openssl_path(), 'rsa', '-pubout', '-text', '-noout',
               '-in', '%s' % in_key]
    # Check if it is public key or private key
    text = open(in_key, 'r').read()
    if '-BEGIN RSA PRIVATE KEY-' in text:
        is_prv_key = True
    elif '-BEGIN PUBLIC KEY-' in text:
        cmdline.extend(['-pubin'])
    else:
        raise Exception('Unknown key format "%s" !' % in_key)

    if pub_key_file:
        cmdline.extend(['-out', '%s' % pub_key_file])
        capture = False
    else:
        capture = True

    output = run_process(cmdline, capture_out=capture)
    if not capture:
        output = text = open(pub_key_file, 'r').read()
    data = output.replace('\r', '')
    data = data.replace('\n', '')
    data = data.replace('  ', '')

    # Extract the modulus
    if is_prv_key:
        match = re.search('modulus(.*)publicExponent:\\s+(\\d+)\\s+', data)
    else:
        match = re.search('Modulus(?:.*?):(.*)Exponent:\\s+(\\d+)\\s+', data)
    if not match:
        raise Exception('Public key not found!')
    modulus = match.group(1).replace(':', '')
    exponent = int(match.group(2))

    mod = bytearray.fromhex(modulus)
    # Remove the '00' from the front if the MSB is 1
    if mod[0] == 0 and (mod[1] & 0x80):
        mod = mod[1:]
    exp = bytearray.fromhex('{:08x}'.format(exponent))

    keydata = mod + exp

    return keydata