Final answer:
Ransomware is the malware that encrypts a computer's data and forces the victim to purchase a decryption code.
Step-by-step explanation:
The malware that encrypts a computer's data, forcing the victim to purchase a decryption code, is called Ransomware. Ransomware is a type of malicious software that locks or encrypts files on a victim's computer, making them inaccessible until a ransom is paid. This form of cyber attack is a growing threat and can cause significant damage to individuals and organizations.