Alexander Peslyak (Александр Песляк) (born 1977), better known as Solar Designer, is a security specialist from Russia. He is best known for his publications on exploitation techniques, including the return-to-libc attack and the first generic heap-based buffer overflow exploitation technique, as well as computer security protection techniques such as privilege separation for daemon processes. Peslyak is the author of the widely popular password cracking tool John the Ripper. His code has also been used in various third-party operating systems, such as OpenBSD and Debian.