Cifrado AES-256
Cifrado de nivel militar para formatos 7z y ZIP
7-Zip uses AES-256 encryption, the same standard adopted by the U.S. government for protecting classified information. This encryption is applied to both 7z and ZIP archive formats.
When creating an archive, you can set a password and choose to encrypt filenames as well, making it impossible for anyone to even see the contents list without the password.
AES-256 is widely considered unbreakable by brute force with current technology. 7-Zip implements it correctly and has been independently audited by the security community.