How do you increase decryption skill in mass effect?

To increase your decryption skill in Mass Effect, focus on investing skill points into the "Decryption" ability when leveling up your character. Additionally, using weapons and equipment that enhance your tech abilities can help improve your effectiveness in hacking and bypassing security systems. Engaging in side missions and exploring different areas will also provide opportunities to practice and level up your decryption skills. Lastly, consider bringing characters with high decryption abilities in your squad to assist with tech-related challenges.