MIT Lincoln Laboratory offers LLCipher, a free, one-week workshop in theoretical cryptography, July 31-August 4, for high-school students in Grades 9-12 interested in math and cyber security. It will be held in-person at MIT Beaverworks (300 Technology Square, Cambridge). Students from underrepresented groups are strongly encouraged to apply. Applications (including transcripts and math teacher recommendation) are due April 28 by 10PM. For more information, email STEM@ll.mit.edu, mentioning LLCipher.