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Allow using bytearrays as tags for AES-CBC

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This commit is contained in:
Kovid Goyal 2016-03-21 22:35:51 +05:30
parent 9e18735d07
commit 4412e80d1d
1 changed files with 20 additions and 4 deletions
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24
src/pyj/aes.pyj
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@ -1,6 +1,8 @@
# vim:fileencoding=utf-8
# License: GPL v3 Copyright: 2016, Kovid Goyal <kovid at kovidgoyal.net>
# Internal API {{{
def string_to_bytes_encoder(string):
return TextEncoder('utf-8').encode(string + '')
@ -218,6 +220,7 @@ def random_bytes_secure(sz):
random_bytes = random_bytes_secure if type(window) is not 'undefined' and window.crypto and type(window.crypto.getRandomValues) is 'function' else random_bytes_insecure
if random_bytes is random_bytes_insecure:
print('WARNING: Using insecure RNG for AES')
# }}}
def generate_key(sz):
if not number_of_rounds[sz]:
@ -225,7 +228,11 @@ def generate_key(sz):
return random_bytes(sz)
def generate_tag(sz):
return String.fromCharCode.apply(None, random_bytes(sz or 16))
return random_bytes(sz or 16)
def typed_array_as_js(x):
name = x.constructor.name or 'Uint8Array'
return '(new ' + name + '(' + JSON.stringify(Array.prototype.slice.call(x)) + '))'
class CBC:
@ -235,7 +242,7 @@ class CBC:
@property
def key_as_js(self):
return '(new Uint8Array(' + JSON.stringify(Array.prototype.slice.call(self.key)) + '))'
return typed_array_as_js(self.key)
def encrypt_bytes(self, bytes, tag_bytes):
iv = first_iv = random_bytes(16)
@ -265,10 +272,19 @@ class CBC:
# Uint8Arrays). If the optional tag (a string) is present, it is also
# encrypted along with plaintext.It can be used to ensure message integrity.
# See the __main__ block at the bottom of this file for example usage.
return self.encrypt_bytes(string_to_bytes(plaintext), string_to_bytes(tag) if tag else Uint8Array(0))
if not tag:
tag = Uint8Array(0)
elif type(tag) is 'string':
tag = string_to_bytes(tag)
return self.encrypt_bytes(string_to_bytes(plaintext), tag)
def decrypt(self, output_from_encrypt, tag):
tag_bytes = string_to_bytes(tag) if tag else Uint8Array(0)
if not tag:
tag_bytes = Uint8Array(0)
elif type(tag) is 'string':
tag_bytes = string_to_bytes(tag)
else:
tag_bytes = tag
iv, inputbytes = output_from_encrypt.iv, output_from_encrypt.cipherbytes
offset = 0
outputbytes = Uint8Array(inputbytes.length)