Manuel Blum

Manuel Blum is a Venezuelan-born American computer scientist who spent most of his career as a professor at the University of California, Berkeley before moving to Carnegie Mellon University in 2001, earning his PhD in mathematics at MIT in 1964 under Marvin Minsky. Blum helped found computational complexity theory as a rigorous field through his work on the Blum complexity axioms and became known for extending complexity ideas into cryptography and program checking, developing methods that let a computer verify whether another program output is correct without needing a trusted correct version to compare against. He co-developed the Blum Blum Shub pseudorandom number generator and the Blum-Goldwasser cryptosystem, and he originated the concept behind CAPTCHA, the widely used test for distinguishing human users from automated programs. Blum received the ACM Turing Award in 1995 for his contributions to the foundations of computational complexity theory and its application to cryptography and program checking, and he was elected to the National Academy of Sciences in 2002.