Which hashing algorithm is considered outdated for security purposes?

MD5 is considered outdated for security purposes due to its vulnerabilities and weaknesses that have been discovered over time. Specifically, MD5 is susceptible to collision attacks, where two different inputs produce the same hash output. This compromise means that an attacker can potentially create a malicious file that matches the hash of a legitimate file, undermining the integrity of data.

As security needs have evolved, more robust hashing algorithms such as SHA-256 and SHA-3 have become the standard. These newer algorithms provide stronger security against both collision and preimage attacks, making MD5 unsuitable for secure applications.

The other choices, while also having their limitations, either serve different purposes (like AES for encryption) or have been succeeded by stronger versions (like SHA-1, which is also falling out of favor but is not as fundamentally flawed as MD5).