Which technique involves capturing user keystrokes to obtain sensitive information?

The technique that involves capturing user keystrokes to obtain sensitive information is keylogging. Keyloggers are a type of malicious software designed specifically to record the keystrokes made on a computer or mobile device. This information can include login credentials, credit card numbers, personal messages, and any other sensitive data the user types. Keylogging is often used by cybercriminals to steal personal information without the user's knowledge.

In contrast, data encryption is a method of protecting data by converting it into a secured format that can only be read by someone with the right decryption key. This does not involve capturing keystrokes and is intended to enhance security.

Malware analysis refers to the process of studying malware to understand its behavior and purpose; it aims at protecting systems from such threats and does not involve the active capture of data from users.

Adware installation typically involves software that automatically displays or downloads advertisements when a user is online, which can lead to privacy issues but does not specifically record keystrokes.

Therefore, keylogging stands out as the correct answer due to its direct mechanism of capturing sensitive information through monitoring user keystrokes.