Boaz Barak:

These are lecture notes for lecture notes for an introductory but fast-paced undergraduate/beginning graduate course on cryptography. I am using these notes for Harvard CS 127.

You can also download all lecture notes in a single PDF file.

If you have any comments, suggestions, typo fixes, etc.. I would be very grateful if you post them as an issue or pull request in the GitHub repository where I am maintaining the source files for these notes.