diff options
Diffstat (limited to 'docs/hazmat')
| -rw-r--r-- | docs/hazmat/primitives/padding.rst | 8 | ||||
| -rw-r--r-- | docs/hazmat/primitives/symmetric-encryption.rst | 12 |
2 files changed, 19 insertions, 1 deletions
diff --git a/docs/hazmat/primitives/padding.rst b/docs/hazmat/primitives/padding.rst index aebb4d4d..4d79ac8f 100644 --- a/docs/hazmat/primitives/padding.rst +++ b/docs/hazmat/primitives/padding.rst @@ -25,8 +25,14 @@ multiple of the block size. >>> padder = padding.PKCS7(128).padder() >>> padder.update(b"1111111111") '' - >>> padder.finalize() + >>> padded_data = padder.finalize() + >>> padded_data '1111111111\x06\x06\x06\x06\x06\x06' + >>> unpadder = padding.PKCS7(128).unpadder() + >>> unpadder.update(padded_data) + '' + >>> unpadder.finalize() + '1111111111' :param block_size: The size of the block in bits that the data is being padded to. diff --git a/docs/hazmat/primitives/symmetric-encryption.rst b/docs/hazmat/primitives/symmetric-encryption.rst index f63ad90a..4ab91408 100644 --- a/docs/hazmat/primitives/symmetric-encryption.rst +++ b/docs/hazmat/primitives/symmetric-encryption.rst @@ -86,6 +86,15 @@ an "encrypt-then-MAC" formulation as `described by Colin Percival`_. everything into the context. Once that is done call ``finalize()`` to finish the operation and obtain the remainder of the data. + Block ciphers require that plaintext or ciphertext always be a multiple of + their block size, because of that **padding** is often required to make a + message the correct size. ``CipherContext`` will not automatically apply + any padding; you'll need to add your own. For block ciphers the reccomended + padding is :class:`cryptography.hazmat.primitives.padding.PKCS7`. If you + are using a stream cipher mode (such as + :class:`cryptography.hazmat.primitives.modes.CTR`) you don't have to worry + about this. + .. method:: update(data) :param bytes data: The data you wish to pass into the context. @@ -101,6 +110,9 @@ an "encrypt-then-MAC" formulation as `described by Colin Percival`_. .. method:: finalize() :return bytes: Returns the remainder of the data. + :raises ValueError: This is raised when the data provided isn't + correctly padded to be a multiple of the + algorithm's block size. Once ``finalize`` is called this object can no longer be used and :meth:`update` and :meth:`finalize` will raise |