diff options
Diffstat (limited to 'docs/hazmat')
-rw-r--r-- | docs/hazmat/primitives/index.rst | 1 | ||||
-rw-r--r-- | docs/hazmat/primitives/padding.rst | 44 |
2 files changed, 45 insertions, 0 deletions
diff --git a/docs/hazmat/primitives/index.rst b/docs/hazmat/primitives/index.rst index 3927f3f0..ee1e251c 100644 --- a/docs/hazmat/primitives/index.rst +++ b/docs/hazmat/primitives/index.rst @@ -14,3 +14,4 @@ Primitives cryptographic-hashes hmac symmetric-encryption + padding diff --git a/docs/hazmat/primitives/padding.rst b/docs/hazmat/primitives/padding.rst new file mode 100644 index 00000000..995ed9f3 --- /dev/null +++ b/docs/hazmat/primitives/padding.rst @@ -0,0 +1,44 @@ +.. danger:: + + This is a "Hazardous Materials" module. You should **ONLY** use it if + you're 100% absolutely sure that you know what you're doing because this + module is full of land mines, dragons, and dinosaurs with laser guns. + + +Padding +======= + + +Padding is a way to take data that may or may not be be a multiple of the block +size for a cipher and extend it out so that it is. This is required for many +block cipher modes as they require the data to be encrypted to be an exact +multiple of the block size. + + +.. class:: cryptography.primitives.padding.PKCS7(block_size) + + PKCS7 padding is a generalization of PKCS5 padding (also known as standard + padding). PKCS7 padding works by appending ``N`` bytes with the value of + ``chr(N)``, where ``N`` is the number of bytes required to make the final + block of data the same size as the block size. A simple example of padding + is: + + .. doctest:: + + >>> from cryptography.primitives import padding + >>> padder = padding.PKCS7(128) + >>> padder.pad(b"1111111111") + '1111111111\x06\x06\x06\x06\x06\x06' + + :param block_size: The size of the block in bits that the data is being + padded to. + + .. method:: pad(data) + + :param data: The data that should be padded. + :rtype bytes: The padded data. + + .. method:: unpad(data) + + :param data: The data that should be unpadded. + :rtype bytes: The unpadded data. |