python: how to encrypt a file?

Can anybody help(or point to some examples) about how to encrypt files with python? I have to use following parameters to encrypt file:

block size=8
iv=qwertyui12345678
method=des3_cbc

Also I have no开发者_如何学JAVA idea about what iv means

Please help. Thanks in advance.

---

You will need to use the Python Crypto Toolkit

IV is the Initialisation Vector.

---

Use pycrypto - note that implmenting crypto properly, even using a library for the hard parts, is tricky. If security matters get expert help.

---

IV stands for Initialization Vector. Block cipher algorithms can be used in several operational modes; one of these modes is called CBC (Cipher-Block Chaining), in this mode the plain text block is XORed with the encrypted previous block. The IV is XORed with the initial plain text block. The IV can be see as an algorithm parameter.

A more detailed description can be read here.