# Key isolation and transaction approval

This module will discuss key isolation and transaction approval. Topics include introduction to hot and cold storage, four-eyes principle, and on/off chain validation.

## Course Objectives

This module contributes to the following course objectives:

1. Describe Bitcoin transactions and ecosystem

## Module Objectives

Upon the completion of this module, you will be able to:

1. Understand the concept of hot and cold storage, and four-eyes principle.
2. Explain how on/off chain validation works.

## Activities and Assessments

- Review all the content and references in the module.
- Start working on Discussion 7.
- Start working on Assignment 4.
- Start working on group research project.