def decrypt(raw, password, salt_mask, key_sz, key_iter, hmac_key_sz,
hmac_key_iter, page_sz, iv_sz, reserve_sz, hmac_sz):
dec = b'SQLite format 3\0'
# derive key
salt_sz = 16
salt = raw[:salt_sz]
key, hmac_key = util.key_derive(salt, password, salt_mask, key_sz,
key_iter, hmac_key_sz, hmac_key_iter)
# decrypt file header, try with default page size
page_sz, reserve_sz = decrypt_page_header(raw, key, salt_sz, page_sz,
iv_sz, reserve_sz)
if page_sz < 0 or reserve_sz < 0:
raise RuntimeError('failed to decide page size or reserve size.')
# decrypt pages
for i in range(0, int(len(raw) / 1024)):
page = util.get_page(raw, page_sz, i + 1)
if i == 0:
# skip salt
page = page[salt_sz:]
page_content = page[:-reserve_sz]
reserve = page[-reserve_sz:]
iv = reserve[:iv_sz]
# check hmac
hmac_old = reserve[iv_sz:iv_sz + hmac_sz]
hmac_new = util.generate_hmac(hmac_key, page_content + iv, i + 1)
if not hmac_old == hmac_new:
raise RuntimeError('hmac check failed in page %d.' % (i + 1))
# decrypt content
page_dec = util.decrypt(page_content, key, iv)
dec += page_dec + util.random_bytes(reserve_sz)
return dec
def decrypt(raw, password, salt_mask, key_sz, key_iter, hmac_key_sz, hmac_key_iter, page_sz, iv_sz, reserve_sz, hmac_sz):
dec = b'SQLite format 3\0'
# derive key
salt_sz = 16
salt = raw[:salt_sz]
key, hmac_key = util.key_derive(salt, password, salt_mask, key_sz, key_iter, hmac_key_sz, hmac_key_iter)
# decrypt file header, try with default page size
page_sz, reserve_sz = decrypt_page_header(raw, key, salt_sz, page_sz, iv_sz, reserve_sz)
if page_sz < 0 or reserve_sz < 0:
raise RuntimeError('failed to decide page size or reserve size.')
# decrypt pages
for i in range(0, int(len(raw) / 1024)):
page = util.get_page(raw, page_sz, i + 1)
if i == 0:
# skip salt
page = page[salt_sz:]
page_content = page[:-reserve_sz]
reserve = page[-reserve_sz:]
iv = reserve[:iv_sz]
# check hmac
hmac_old = reserve[iv_sz:iv_sz+hmac_sz]
hmac_new = util.generate_hmac(hmac_key, page_content + iv, i + 1)
if not hmac_old == hmac_new:
raise RuntimeError('hmac check failed in page %d.' % (i+1))
# decrypt content
page_dec = util.decrypt(page_content, key, iv)
dec += page_dec + util.random_bytes(reserve_sz)
return dec
def fast_stream_decrypt(filename_in: str, password: bytearray,
filename_out: str):
with open(filename_in,
'rb') as enc, open(filename_out,
'wb',
buffering=config.page_sz * 16) as dec:
enc_size = os.path.getsize(enc.name)
dec.write(config.header)
first_page = enc.read(config.page_sz)
# derive key
salt_sz = 16
salt = first_page[:salt_sz]
key, hmac_key = util.key_derive(salt, password, config.salt_mask,
config.key_sz, config.key_iter,
config.hmac_key_sz,
config.hmac_key_iter)
# decrypt file header, try with default page size
page_sz, reserve_sz = decrypt_page_header(first_page, key, salt_sz,
config.page_sz, config.iv_sz,
config.reserve_sz)
if page_sz < 0 or reserve_sz < 0:
raise RuntimeError('failed to decide page size or reserve size.')
enc.seek(0)
for i in tqdm(range(0, int(enc_size / 1024))):
page = enc.read(config.page_sz)
if i == 0:
page = page[salt_sz:]
page_content = page[:-reserve_sz]
reserve = page[-reserve_sz:]
iv = reserve[:config.iv_sz]
dec.write(util.decrypt(page_content, key, iv))
dec.write(util.random_bytes(reserve_sz))
dec.flush()
def decrypt_by_reserve_size(first_page_without_salt, key, iv_sz, reserve_sz):
"""Decrypt page content using specified reserve size"""
reserve = first_page_without_salt[-reserve_sz:]
iv = reserve[:iv_sz]
return util.decrypt(first_page_without_salt, key, iv)
def decrypt_by_reserve_size(first_page_without_salt, key, iv_sz, reserve_sz):
"""Decrypt page content using specified reserve size"""
reserve = first_page_without_salt[-reserve_sz:]
iv = reserve[:iv_sz]
return util.decrypt(first_page_without_salt, key, iv)