Blaise de Vigenère was a French diplomat and cryptographer born in 1523. He is best known for developing the Vigenère cipher, a method of encrypting messages that uses a keyword to create a more complex substitution cipher. This technique significantly improved the security of written communication during his time. Vigenère's work in cryptography laid the foundation for modern encryption methods. His cipher remained unbroken for many years and was widely used until the advent of more advanced techniques. He also contributed to the fields of mathematics and astrology, showcasing his diverse interests and expertise.