Steps Toward Unraveling a Vatican Cipher of the 1930s
A handful of letters sent in the 1930s by the Berlin Nunciature to the Vatican Secretariat of State contain encrypted portions along with their clear-text versions. These Rosetta-stone-like documents enable a partial unraveling of the adopted cipher system, which has the structure of a substitution-type nomenclator. Apparently, no cipher is used more than once and different ciphers are related through an indicator. The findings are offered as a stepping stone for the benefit of future investigators.
vatican ciphers nomenclator ciphers rosetta-stone documents