Gilbert Vernam
More info
- Born
- Died
- Known for
- The Vernam cipher
- Nationality
- American
The AT&T engineer who in 1917 patented the XOR encryption that would become the only provably unbreakable cipher.
American engineer at AT&T's research department. In 1917 he built a system in which teleprinter characters were combined bit by bit with characters from a paper key tape, using what we now call XOR. Encryption happened at the moment of transmission, which was new — earlier ciphers required manual work before and after sending.
Vernam's own design ran the key tape in a loop, which made it breakable. Joseph Mauborgne realised the key had to be truly random and used exactly once; then, and only then, is the cipher perfect. Claude Shannon proved the point mathematically only in 1949. Vernam himself never made any money from the invention.