graphene/Pal/src/host/Linux-SGX/signer/pal-sgx-sign

#!/usr/bin/env python3
# pylint: disable=invalid-name

import argparse
import datetime
import functools
import hashlib
import os
import struct
import subprocess
import sys

sys.path.insert(0, os.path.dirname(os.path.dirname(__file__)))
import generated_offsets as offs # pylint: disable=import-error,wrong-import-position

# pylint: enable=invalid-name

# Default / Architectural Options

ARCHITECTURE = "amd64"

SSAFRAMESIZE = offs.PAGESIZE

DEFAULT_ENCLAVE_SIZE = '256M'
DEFAULT_THREAD_NUM = 4
ENCLAVE_HEAP_MIN = offs.DEFAULT_HEAP_MIN


# Utilities

ZERO_PAGE = bytes(offs.PAGESIZE)


def roundup(addr):
    remaining = addr % offs.PAGESIZE
    if remaining:
        return addr + (offs.PAGESIZE - remaining)
    return addr


def rounddown(addr):
    return addr - addr % offs.PAGESIZE


def parse_size(value):
    scale = 1
    if value.endswith("K"):
        scale = 1024
    if value.endswith("M"):
        scale = 1024 * 1024
    if value.endswith("G"):
        scale = 1024 * 1024 * 1024
    if scale != 1:
        value = value[:-1]
    return int(value, 0) * scale


# Reading / Writing Manifests

def read_manifest(filename):
    manifest = dict()
    manifest_layout = []
    with open(filename, "r") as file:
        for line in file:
            if line == "":
                manifest_layout.append((None, None))
                break

            pound = line.find("#")
            if pound != -1:
                comment = line[pound:].strip()
                line = line[:pound]
            else:
                comment = None

            line = line.strip()
            equal = line.find("=")
            if equal != -1:
                key = line[:equal].strip()
                manifest[key] = line[equal + 1:].strip()
            else:
                key = None

            manifest_layout.append((key, comment))

    return (manifest, manifest_layout)


def exec_sig_manifest(args, manifest):
    if 'exec' not in args or args.get('depend'):
        if 'loader.exec' in manifest:
            exec_url = manifest['loader.exec']
            if not exec_url.startswith('file:'):
                print("executable must be a local file", file=sys.stderr)
                return 1

            exec_path = exec_url[5:]  # strip preceding 'file:'
            if os.path.isabs(exec_path):
                args['exec'] = exec_path
            else:
                args['exec'] = os.path.join(
                    os.path.dirname(args['manifest']), exec_path)

    if 'sgx.sigfile' in manifest:
        args['sigfile'] = resolve_uri(manifest['sgx.sigfile'],
                                      check_exist=False)
    else:
        sigfile = args['output']
        for ext in ['.manifest.sgx.d', '.manifest.sgx', '.manifest']:
            if sigfile.endswith(ext):
                sigfile = sigfile[:-len(ext)]
                break
        args['sigfile'] = sigfile + '.sig'
        manifest['sgx.sigfile'] = 'file:' + os.path.basename(args['sigfile'])

    return 0


def output_manifest(filename, manifest, manifest_layout):
    with open(filename, 'w') as file:
        written = []

        file.write('# DO NOT MODIFY. THIS FILE WAS AUTO-GENERATED.\n\n')

        for (key, comment) in manifest_layout:
            line = ''
            if key is not None:
                line += key + ' = ' + manifest[key]
                written.append(key)
            if comment is not None:
                if line != '':
                    line += ' '
                line += comment
            file.write(line)
            file.write('\n')

        file.write('\n')
        file.write('# Generated by Graphene\n')
        file.write('\n')

        for key in sorted(manifest):
            if key not in written:
                file.write("%s = %s\n" % (key, manifest[key]))


# Loading Enclave Attributes

def get_enclave_attributes(manifest):
    sgx_flags = {
        'FLAG_DEBUG': struct.pack("<Q", offs.SGX_FLAGS_DEBUG),
        'FLAG_MODE64BIT': struct.pack("<Q", offs.SGX_FLAGS_MODE64BIT),
    }

    sgx_xfrms = {
        'XFRM_LEGACY': struct.pack("<Q", offs.SGX_XFRM_LEGACY),
        'XFRM_AVX': struct.pack("<Q", offs.SGX_XFRM_AVX),
        'XFRM_AVX512': struct.pack("<Q", offs.SGX_XFRM_AVX512),
        'XFRM_MPX': struct.pack("<Q", offs.SGX_XFRM_MPX),
    }

    sgx_miscs = {
        'MISC_EXINFO': struct.pack("<L", offs.SGX_MISCSELECT_EXINFO),
    }

    default_attributes = {
        'FLAG_DEBUG',
        'XFRM_LEGACY',
    }

    if ARCHITECTURE == 'amd64':
        default_attributes.add('FLAG_MODE64BIT')

    manifest_options = {
        'debug': 'FLAG_DEBUG',
        'require_avx': 'XFRM_AVX',
        'require_avx512': 'XFRM_AVX512',
        'require_mpx': 'XFRM_MPX',
        'support_exinfo': 'MISC_EXINFO',
    }

    attributes = default_attributes

    for opt in manifest_options:
        key = 'sgx.' + opt
        if key in manifest:
            if manifest[key] == '1':
                attributes.add(manifest_options[opt])
            else:
                attributes.discard(manifest_options[opt])

    flags_raw = struct.pack("<Q", 0)
    xfrms_raw = struct.pack("<Q", 0)
    miscs_raw = struct.pack("<L", 0)

    for attr in attributes:
        if attr in sgx_flags:
            flags_raw = bytes([a | b for a, b in
                               zip(flags_raw, sgx_flags[attr])])
        if attr in sgx_xfrms:
            xfrms_raw = bytes([a | b for a, b in
                               zip(xfrms_raw, sgx_xfrms[attr])])
        if attr in sgx_miscs:
            miscs_raw = bytes([a | b for a, b in
                               zip(miscs_raw, sgx_miscs[attr])])

    return flags_raw, xfrms_raw, miscs_raw


# Generate Checksums / Measurement

def resolve_uri(uri, check_exist=True):
    orig_uri = uri
    if uri.startswith('file:'):
        target = os.path.normpath(uri[5:])
    else:
        target = os.path.normpath(uri)
    if check_exist and not os.path.exists(target):
        raise Exception(
            'Cannot resolve ' + orig_uri + ' or the file does not exist.')
    return target


def get_checksum(filename):
    digest = hashlib.sha256()
    with open(filename, 'rb') as file:
        digest.update(file.read())
    return digest.digest()


def get_trusted_files(manifest, args, check_exist=True, do_checksum=True):
    targets = dict()

    if 'exec' in args:
        targets['exec'] = (args['exec'], resolve_uri(args['exec'],
                                                     check_exist))

    if 'loader.preload' in manifest:
        for i, uri in enumerate(str.split(manifest['loader.preload'], ',')):
            targets['preload' + str(i)] = (uri, resolve_uri(uri, check_exist))

    for (key, val) in manifest.items():
        if not key.startswith('sgx.trusted_files.'):
            continue
        key = key[len('sgx.trusted_files.'):]
        if key in targets:
            raise Exception(
                'repeated key in manifest: sgx.trusted_files.' + key)
        targets[key] = (val, resolve_uri(val, check_exist))

    if do_checksum:
        for (key, val) in targets.items():
            (uri, target) = val
            checksum = get_checksum(target).hex()
            targets[key] = (uri, target, checksum)

    return targets


def get_trusted_children(manifest, check_exist=True, do_checksum=True):
    targets = dict()

    for (key, val) in manifest.items():
        if not key.startswith('sgx.trusted_children.'):
            continue
        key = key[len('sgx.trusted_children.'):]
        if key in targets:
            raise Exception(
                'repeated key in manifest: sgx.trusted_children.' + key)

        target = resolve_uri(val, check_exist)
        if not target.endswith('.sig'):
            target += '.sig'
        if do_checksum:
            sig = open(target, 'rb').read()[
                offs.SGX_ARCH_ENCLAVE_CSS_ENCLAVE_HASH:
                offs.SGX_ARCH_ENCLAVE_CSS_ENCLAVE_HASH + offs.SGX_HASH_SIZE].hex()
            targets[key] = (val, target, sig)
        else:
            targets[key] = (val, target)
    return targets


# Populate Enclave Memory

PAGEINFO_R = 0x1
PAGEINFO_W = 0x2
PAGEINFO_X = 0x4
PAGEINFO_TCS = 0x100
PAGEINFO_REG = 0x200


def get_loadcmds(filename):
    loadcmds = []
    proc = subprocess.Popen(['readelf', '-l', '-W', filename],
                         stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    while True:
        line = proc.stdout.readline()
        if not line:
            break
        line = line.decode()
        stripped = line.strip()
        if not stripped.startswith('LOAD'):
            continue
        tokens = stripped.split()
        if len(tokens) < 6:
            continue
        if len(tokens) >= 7 and tokens[7] == "E":
            tokens[6] += tokens[7]
        prot = 0
        for token in tokens[6]:
            if token == "R":
                prot = prot | 4
            if token == "W":
                prot = prot | 2
            if token == "E":
                prot = prot | 1

        loadcmds.append((int(tokens[1][2:], 16),  # offset
                         int(tokens[2][2:], 16),  # addr
                         int(tokens[4][2:], 16),  # filesize
                         int(tokens[5][2:], 16),  # memsize
                         prot))
    proc.wait()
    if proc.returncode != 0:
        return None
    return loadcmds


class MemoryArea:
    # pylint: disable=too-few-public-methods,too-many-instance-attributes
    def __init__(self, desc, file=None, content=None, addr=None, size=None,
                 flags=None, measure=True):
        # pylint: disable=too-many-arguments
        self.desc = desc
        self.file = file
        self.content = content
        self.addr = addr
        self.size = size
        self.flags = flags
        self.is_binary = False
        self.measure = measure

        if file:
            loadcmds = get_loadcmds(file)
            if loadcmds:
                mapaddr = 0xffffffffffffffff
                mapaddr_end = 0
                for (_, addr_, _, memsize, _) in loadcmds:
                    if rounddown(addr_) < mapaddr:
                        mapaddr = rounddown(addr_)
                    if roundup(addr_ + memsize) > mapaddr_end:
                        mapaddr_end = roundup(addr_ + memsize)

                self.is_binary = True
                self.size = mapaddr_end - mapaddr
                if mapaddr > 0:
                    self.addr = mapaddr
            else:
                self.size = os.stat(file).st_size

        if self.addr is not None:
            self.addr = rounddown(self.addr)
        if self.size is not None:
            self.size = roundup(self.size)


def get_memory_areas(attr, args):
    areas = []
    areas.append(
        MemoryArea('ssa',
                   size=attr['thread_num'] * SSAFRAMESIZE * offs.SSAFRAMENUM,
                   flags=PAGEINFO_R | PAGEINFO_W | PAGEINFO_REG))
    areas.append(MemoryArea('tcs', size=attr['thread_num'] * offs.TCS_SIZE,
                            flags=PAGEINFO_TCS))
    areas.append(MemoryArea('tls', size=attr['thread_num'] * offs.PAGESIZE,
                            flags=PAGEINFO_R | PAGEINFO_W | PAGEINFO_REG))

    for _ in range(attr['thread_num']):
        areas.append(MemoryArea('stack', size=offs.ENCLAVE_STACK_SIZE,
                                flags=PAGEINFO_R | PAGEINFO_W | PAGEINFO_REG))

    areas.append(MemoryArea('pal', file=args['libpal'], flags=PAGEINFO_REG))

    if 'exec' in args:
        areas.append(MemoryArea('exec', file=args['exec'],
                                flags=PAGEINFO_W | PAGEINFO_REG))
    return areas


def find_areas(areas, desc):
    return [area for area in areas if area.desc == desc]


def find_area(areas, desc, allow_none=False):
    matching = find_areas(areas, desc)

    if not matching and allow_none:
        return None

    if len(matching) != 1:
        raise KeyError(
            "Could not find exactly one MemoryArea '{}'".format(desc))

    return matching[0]


def entry_point(elf_path):
    env = os.environ
    env['LC_ALL'] = 'C'
    out = subprocess.check_output(
        ['readelf', '-l', '--', elf_path], env=env)
    for line in out.splitlines():
        line = line.decode()
        if line.startswith("Entry point "):
            return int(line[12:], 0)
    raise ValueError("Could not find entry point of elf file")


def baseaddr():
    if ENCLAVE_HEAP_MIN == 0:
        return offs.ENCLAVE_HIGH_ADDRESS
    return 0


def gen_area_content(attr, areas):
    # pylint: disable=too-many-locals
    manifest_area = find_area(areas, 'manifest')
    exec_area = find_area(areas, 'exec', True)
    pal_area = find_area(areas, 'pal')
    ssa_area = find_area(areas, 'ssa')
    tcs_area = find_area(areas, 'tcs')
    tls_area = find_area(areas, 'tls')
    stacks = find_areas(areas, 'stack')

    tcs_data = bytearray(tcs_area.size)

    def set_tcs_field(t, offset, pack_fmt, value):
        struct.pack_into(pack_fmt, tcs_data, t * offs.TCS_SIZE + offset, value)

    tls_data = bytearray(tls_area.size)

    def set_tls_field(t, offset, value):
        struct.pack_into('<Q', tls_data, t * offs.PAGESIZE + offset, value)

    enclave_heap_max = pal_area.addr - offs.MEMORY_GAP

    # Sanity check that we measure everything except the heap which is zeroed
    # on enclave startup.
    for area in areas:
        if (area.addr + area.size <= ENCLAVE_HEAP_MIN or
                area.addr >= enclave_heap_max or area is exec_area):
            if not area.measure:
                raise ValueError("Memory area, which is not the heap, "
                                 "is not measured")
        elif area.desc != 'free':
            raise ValueError("Unexpected memory area is in heap range")

    for t in range(0, attr['thread_num']):
        ssa_offset = ssa_area.addr + SSAFRAMESIZE * offs.SSAFRAMENUM * t
        ssa = baseaddr() + ssa_offset
        set_tcs_field(t, offs.TCS_OSSA, '<Q', ssa_offset)
        set_tcs_field(t, offs.TCS_NSSA, '<L', offs.SSAFRAMENUM)
        set_tcs_field(t, offs.TCS_OENTRY, '<Q',
                      pal_area.addr + entry_point(pal_area.file))
        set_tcs_field(t, offs.TCS_OGS_BASE, '<Q', tls_area.addr + offs.PAGESIZE * t)
        set_tcs_field(t, offs.TCS_OFS_LIMIT, '<L', 0xfff)
        set_tcs_field(t, offs.TCS_OGS_LIMIT, '<L', 0xfff)

        set_tls_field(t, offs.SGX_COMMON_SELF,
                      tls_area.addr + offs.PAGESIZE * t + baseaddr())
        set_tls_field(t, offs.SGX_ENCLAVE_SIZE, attr['enclave_size'])
        set_tls_field(t, offs.SGX_TCS_OFFSET, tcs_area.addr + offs.TCS_SIZE * t)
        set_tls_field(t, offs.SGX_INITIAL_STACK_OFFSET,
                      stacks[t].addr + stacks[t].size)
        set_tls_field(t, offs.SGX_SSA, ssa)
        set_tls_field(t, offs.SGX_GPR, ssa + SSAFRAMESIZE - offs.SGX_GPR_SIZE)
        set_tls_field(t, offs.SGX_MANIFEST_SIZE,
                      os.stat(manifest_area.file).st_size)
        set_tls_field(t, offs.SGX_HEAP_MIN, baseaddr() + ENCLAVE_HEAP_MIN)
        set_tls_field(t, offs.SGX_HEAP_MAX, baseaddr() + enclave_heap_max)
        if exec_area is not None:
            set_tls_field(t, offs.SGX_EXEC_ADDR, baseaddr() + exec_area.addr)
            set_tls_field(t, offs.SGX_EXEC_SIZE, exec_area.size)

    tcs_area.content = tcs_data
    tls_area.content = tls_data


def populate_memory_areas(attr, areas):
    populating = attr['enclave_size']

    for area in areas:
        if area.addr is not None:
            continue

        area.addr = populating - area.size
        if area.addr < ENCLAVE_HEAP_MIN:
            raise Exception("Enclave size is not large enough")
        populating = max(area.addr - offs.MEMORY_GAP, 0)

    free_areas = []
    for area in areas:
        if area.addr + area.size + offs.MEMORY_GAP < populating:
            addr = area.addr + area.size + offs.MEMORY_GAP
            flags = PAGEINFO_R | PAGEINFO_W | PAGEINFO_X | PAGEINFO_REG
            free_areas.append(
                MemoryArea('free', addr=addr, size=populating - addr,
                           flags=flags, measure=False))
            populating = max(area.addr - offs.MEMORY_GAP, 0)

    if populating > ENCLAVE_HEAP_MIN:
        flags = PAGEINFO_R | PAGEINFO_W | PAGEINFO_X | PAGEINFO_REG
        free_areas.append(
            MemoryArea('free', addr=ENCLAVE_HEAP_MIN,
                       size=populating - ENCLAVE_HEAP_MIN, flags=flags,
                       measure=False))

    gen_area_content(attr, areas)

    return areas + free_areas


def generate_measurement(attr, areas):
    # pylint: disable=too-many-statements,too-many-branches,too-many-locals

    def do_ecreate(digest, size):
        data = struct.pack("<8sLQ44s", b"ECREATE", SSAFRAMESIZE // offs.PAGESIZE,
                           size, b"")
        digest.update(data)

    def do_eadd(digest, offset, flags):
        data = struct.pack("<8sQQ40s", b"EADD", offset, flags, b"")
        digest.update(data)

    def do_eextend(digest, offset, content):
        if len(content) != 256:
            raise ValueError("Exactly 256 bytes expected")

        data = struct.pack("<8sQ48s", b"EEXTEND", offset, b"")
        digest.update(data)
        digest.update(content)

    def include_page(digest, offset, flags, content, measure):
        if len(content) != offs.PAGESIZE:
            raise ValueError("Exactly one page expected")

        do_eadd(digest, offset, flags)
        if measure:
            for i in range(0, offs.PAGESIZE, 256):
                do_eextend(digest, offset + i, content[i:i + 256])

    mrenclave = hashlib.sha256()
    do_ecreate(mrenclave, attr['enclave_size'])

    def print_area(addr, size, flags, desc, measured):
        if flags & PAGEINFO_REG:
            type_ = 'REG'
        if flags & PAGEINFO_TCS:
            type_ = 'TCS'
        prot = ['-', '-', '-']
        if flags & PAGEINFO_R:
            prot[0] = 'R'
        if flags & PAGEINFO_W:
            prot[1] = 'W'
        if flags & PAGEINFO_X:
            prot[2] = 'X'
        prot = ''.join(prot)

        desc = '(' + desc + ')'
        if measured:
            desc += ' measured'

        if size == offs.PAGESIZE:
            print("    %016x [%s:%s] %s" % (addr, type_, prot, desc))
        else:
            print("    %016x-%016lx [%s:%s] %s" %
                  (addr, addr + size, type_, prot, desc))

    def load_file(digest, file, offset, addr, filesize, memsize, desc, flags):
        # pylint: disable=too-many-arguments
        f_addr = rounddown(offset)
        m_addr = rounddown(addr)
        m_size = roundup(addr + memsize) - m_addr

        print_area(m_addr, m_size, flags, desc, True)

        for page in range(m_addr, m_addr + m_size, offs.PAGESIZE):
            start = page - m_addr + f_addr
            end = start + offs.PAGESIZE
            start_zero = b""
            if start < offset:
                if offset - start >= offs.PAGESIZE:
                    start_zero = ZERO_PAGE
                else:
                    start_zero = bytes(offset - start)
            end_zero = b""
            if end > offset + filesize:
                if end - offset - filesize >= offs.PAGESIZE:
                    end_zero = ZERO_PAGE
                else:
                    end_zero = bytes(end - offset - filesize)
            start += len(start_zero)
            end -= len(end_zero)
            if start < end:
                file.seek(start)
                data = file.read(end - start)
            else:
                data = b""
            if len(start_zero + data + end_zero) != offs.PAGESIZE:
                raise Exception("wrong calculation")

            include_page(digest, page, flags, start_zero + data + end_zero, True)

    for area in areas:
        if area.file:
            with open(area.file, 'rb') as file:
                if area.is_binary:
                    loadcmds = get_loadcmds(area.file)
                    if loadcmds:
                        mapaddr = 0xffffffffffffffff
                        for (offset, addr, filesize, memsize,
                             prot) in loadcmds:
                            if rounddown(addr) < mapaddr:
                                mapaddr = rounddown(addr)
                    baseaddr_ = area.addr - mapaddr
                    for (offset, addr, filesize, memsize, prot) in loadcmds:
                        flags = area.flags
                        if prot & 4:
                            flags = flags | PAGEINFO_R
                        if prot & 2:
                            flags = flags | PAGEINFO_W
                        if prot & 1:
                            flags = flags | PAGEINFO_X

                        if flags & PAGEINFO_X:
                            desc = 'code'
                        else:
                            desc = 'data'
                        load_file(mrenclave, file, offset, baseaddr_ + addr,
                                  filesize, memsize, desc, flags)
                else:
                    load_file(mrenclave, file, 0, area.addr,
                              os.stat(area.file).st_size, area.size,
                              area.desc, area.flags)
        else:
            for addr in range(area.addr, area.addr + area.size, offs.PAGESIZE):
                data = ZERO_PAGE
                if area.content is not None:
                    start = addr - area.addr
                    end = start + offs.PAGESIZE
                    data = area.content[start:end]

                include_page(mrenclave, addr, area.flags, data, area.measure)

            print_area(area.addr, area.size, area.flags, area.desc,
                       area.measure)

    return mrenclave.digest()


def generate_sigstruct(attr, args, mrenclave):
    '''Generate Sigstruct.

    field format: (offset, type, value)
    ''' # pylint: disable=too-many-locals

    fields = {
        'header': (offs.SGX_ARCH_ENCLAVE_CSS_HEADER,
                   "<4L", 0x00000006, 0x000000e1, 0x00010000, 0x00000000),
        'module_vendor': (offs.SGX_ARCH_ENCLAVE_CSS_MODULE_VENDOR, "<L", 0x00000000),
        'date': (offs.SGX_ARCH_ENCLAVE_CSS_DATE, "<HBB", attr['year'], attr['month'], attr['day']),
        'header2': (offs.SGX_ARCH_ENCLAVE_CSS_HEADER2,
                    "<4L", 0x00000101, 0x00000060, 0x00000060, 0x00000001),
        'hw_version': (offs.SGX_ARCH_ENCLAVE_CSS_HW_VERSION, "<L", 0x00000000),
        'misc_select': (offs.SGX_ARCH_ENCLAVE_CSS_MISC_SELECT, "4s", attr['misc_select']),
        'misc_mask': (offs.SGX_ARCH_ENCLAVE_CSS_MISC_MASK, "4s", attr['misc_select']),
        'attributes': (offs.SGX_ARCH_ENCLAVE_CSS_ATTRIBUTES, "8s8s", attr['flags'], attr['xfrms']),
        'attribute_mask': (offs.SGX_ARCH_ENCLAVE_CSS_ATTRIBUTE_MASK,
                           "8s8s", attr['flags'], attr['xfrms']),
        'enclave_hash': (offs.SGX_ARCH_ENCLAVE_CSS_ENCLAVE_HASH, "32s", mrenclave),
        'isv_prod_id': (offs.SGX_ARCH_ENCLAVE_CSS_ISV_PROD_ID, "<H", attr['isv_prod_id']),
        'isv_svn': (offs.SGX_ARCH_ENCLAVE_CSS_ISV_SVN, "<H", attr['isv_svn']),
    }

    sign_buffer = bytearray(128 + 128)

    for field in fields.values():
        if field[0] >= offs.SGX_ARCH_ENCLAVE_CSS_MISC_SELECT:
            struct.pack_into(field[1], sign_buffer,
                             field[0] - offs.SGX_ARCH_ENCLAVE_CSS_MISC_SELECT + 128,
                             *field[2:])
        else:
            struct.pack_into(field[1], sign_buffer, field[0], *field[2:])

    proc = subprocess.Popen(
        ['openssl', 'rsa', '-modulus', '-in', args['key'], '-noout'],
        stdout=subprocess.PIPE)
    modulus_out, _ = proc.communicate()
    modulus = bytes.fromhex(modulus_out[8:8+offs.SE_KEY_SIZE*2].decode())
    modulus = bytes(reversed(modulus))

    proc = subprocess.Popen(
        ['openssl', 'sha256', '-binary', '-sign', args['key']],
        stdin=subprocess.PIPE, stdout=subprocess.PIPE)
    signature, _ = proc.communicate(sign_buffer)
    signature = signature[::-1]

    modulus_int = int.from_bytes(modulus, byteorder='little')
    signature_int = int.from_bytes(signature, byteorder='little')

    tmp1 = signature_int * signature_int
    q1_int = tmp1 // modulus_int
    tmp2 = tmp1 % modulus_int
    q2_int = tmp2 * signature_int // modulus_int

    q1 = q1_int.to_bytes(384, byteorder='little') # pylint: disable=invalid-name
    q2 = q2_int.to_bytes(384, byteorder='little') # pylint: disable=invalid-name

    fields.update({
        'modulus': (offs.SGX_ARCH_ENCLAVE_CSS_MODULUS, "384s", modulus),
        'exponent': (offs.SGX_ARCH_ENCLAVE_CSS_EXPONENT, "<L", 3),
        'signature': (offs.SGX_ARCH_ENCLAVE_CSS_SIGNATURE, "384s", signature),

        'q1': (offs.SGX_ARCH_ENCLAVE_CSS_Q1, "384s", q1),
        'q2': (offs.SGX_ARCH_ENCLAVE_CSS_Q2, "384s", q2),
    })

    buffer = bytearray(offs.SGX_ARCH_ENCLAVE_CSS_SIZE)

    for field in fields.values():
        struct.pack_into(field[1], buffer, field[0], *field[2:])

    return buffer


# Main Program

argparser = argparse.ArgumentParser(
    epilog='With sign mode(without -depend), libpal and key are also required')
argparser.add_argument('--output', '-output', metavar='OUTPUT',
                       type=str, required=True,
                       help='Output .manifest.sgx file '
                            '(manifest augmented with autogenerated fields)')
argparser.add_argument('--libpal', '-libpal', metavar='LIBPAL',
                       type=str, required=False,
                       help='Input libpal file '
                            '(required as part of the enclave measurement)')
argparser.add_argument('--key', '-key', metavar='KEY',
                       type=str, required=False,
                       help='specify signing key(.pem) file')
argparser.add_argument('--manifest', '-manifest', metavar='MANIFEST',
                       type=str, required=True,
                       help='Input .manifest file '
                            '(user-prepared manifest template)')
argparser.add_argument('--exec', '-exec', metavar='EXEC',
                       type=str, required=False,
                       help='Input executable file '
                            '(required as part of the enclave measurement)')
argparser.add_argument('--depend', '-depend',
                       action='store_true', required=False,
                       help='Generate dependency for Makefile')


def parse_args(args):
    args = argparser.parse_args(args)
    args_dict = {
        'output': args.output,
        'libpal': args.libpal,
        'key': args.key,
        'manifest': args.manifest,
    }
    if args.exec is not None:
        args_dict['exec'] = args.exec
    if args.depend:
        args_dict['depend'] = True
    else:
        # libpal and key are required
        if args.libpal is None or args.key is None:
            argparser.error("libpal and key are also required to sign")
            return None

    return args_dict


def main_sign(args):
    # pylint: disable=too-many-statements,too-many-branches,too-many-locals
    manifest, manifest_layout = read_manifest(args['manifest'])

    if exec_sig_manifest(args, manifest) != 0:
        return 1

    # Get attributes from manifest
    attr = dict()

    parse_int = functools.partial(int, base=0)

    for key, default, parse, attr_key in [
            ('enclave_size', DEFAULT_ENCLAVE_SIZE, parse_size, 'enclave_size'),
            ('thread_num', str(DEFAULT_THREAD_NUM), parse_int, 'thread_num'),
            ('isvprodid', '0', parse_int, 'isv_prod_id'),
            ('isvsvn', '0', parse_int, 'isv_svn'),
    ]:
        attr[attr_key] = parse(manifest.setdefault('sgx.' + key, default))

    (attr['flags'], attr['xfrms'], attr['misc_select']) = get_enclave_attributes(manifest)

    today = datetime.date.today()
    attr['year'] = today.year
    attr['month'] = today.month
    attr['day'] = today.day

    print("Attributes:")
    print("    size:        %d" % attr['enclave_size'])
    print("    thread_num:  %d" % attr['thread_num'])
    print("    isv_prod_id: %d" % attr['isv_prod_id'])
    print("    isv_svn:     %d" % attr['isv_svn'])
    print("    attr.flags:  %016x" % int.from_bytes(attr['flags'], byteorder='big'))
    print("    attr.xfrm:   %016x" % int.from_bytes(attr['xfrms'], byteorder='big'))
    print("    misc_select: %08x" % int.from_bytes(attr['misc_select'], byteorder='big'))
    print("    date:        %d-%02d-%02d" % (attr['year'], attr['month'], attr['day']))

    # Check client info for remote attestation
    # (if sgx.ra_client.spid is provided)
    print("Attestation:")
    if 'sgx.ra_client_spid' in manifest and manifest['sgx.ra_client_spid']:
        print("    spid:     " + manifest['sgx.ra_client_spid'])
        if 'sgx.ra_client_key' in manifest and manifest['sgx.ra_client_key']:
            print("    key:   " + manifest['sgx.ra_client_key'])
        else:
            print("    *** sgx.ra_client_key not specified ***")
            return 1
        if 'sgx.ra_client_linkable' in manifest:
            print("    linkable: " + manifest['sgx.ra_client_linkable'])
        else:
            print("    linkable: 0")
    else:
        print("    *** Client info is not specified. Graphene will not perform"
              " remote attestation before execution. Please provide"
              " sgx.ra_client_spid and sgx.ra_client_key in the manifest. ***")

    # Get trusted checksums and measurements
    print("Trusted files:")
    for key, val in get_trusted_files(manifest, args).items():
        (uri, _, checksum) = val
        print("    %s %s" % (checksum, uri))
        manifest['sgx.trusted_checksum.' + key] = checksum

    print("Trusted children:")
    for key, val in get_trusted_children(manifest).items():
        (uri, _, mrenclave) = val
        print("    %s %s" % (mrenclave, uri))
        manifest['sgx.trusted_mrenclave.' + key] = mrenclave

    # Try populate memory areas
    memory_areas = get_memory_areas(attr, args)

    if manifest.get('sgx.static_address', None) is None:
        # If static_address is not specified explicitly, deduce from executable
        if any([a.addr is not None for a in memory_areas]):
            manifest['sgx.static_address'] = '1'
        else:
            global ENCLAVE_HEAP_MIN # pylint: disable=global-statement
            ENCLAVE_HEAP_MIN = 0
            manifest['sgx.static_address'] = '0'

    if manifest.get('sgx.allow_file_creation', None) is None:
        manifest['sgx.allow_file_creation'] = '0'

    output_manifest(args['output'], manifest, manifest_layout)

    memory_areas = [
        MemoryArea('manifest', file=args['output'],
                   flags=PAGEINFO_R | PAGEINFO_REG)
        ] + memory_areas

    memory_areas = populate_memory_areas(attr, memory_areas)

    print("Memory:")
    # Generate measurement
    mrenclave = generate_measurement(attr, memory_areas)
    print("Measurement:")
    print("    %s" % mrenclave.hex())

    # Generate sigstruct
    open(args['sigfile'], 'wb').write(
        generate_sigstruct(attr, args, mrenclave))
    return 0


def make_depend(args):
    manifest_file = args['manifest']
    output = args['output']

    (manifest, _) = read_manifest(manifest_file)
    if exec_sig_manifest(args, manifest) != 0:
        return 1

    dependencies = set()
    for filename in get_trusted_files(manifest, args, check_exist=False,
                                      do_checksum=False).values():
        dependencies.add(filename[1])
    for filename in get_trusted_children(manifest, check_exist=False,
                                         do_checksum=False).values():
        dependencies.add(filename[1])

    with open(output, 'w') as file:
        manifest_sgx = output
        if manifest_sgx.endswith('.d'):
            manifest_sgx = manifest_sgx[:-len('.d')]
        file.write('%s %s:' % (manifest_sgx, args['sigfile']))
        for filename in dependencies:
            file.write(' \\\n\t%s' % filename)
        file.write('\n')

    return 0


def main(args=None):
    args = parse_args(args)
    if args is None:
        return 1

    if args.get('depend'):
        return make_depend(args)
    return main_sign(args)


if __name__ == "__main__":
    sys.exit(main())