08-12-2022, 01:43 PM
Having thought a little more about it I would correct myself, I think more than 1% of cipher keys survive maybe more than 5%. I say this as a few cipher ledgers survive and one can guesstimate the number of ledgers there would have been at that time e.g. one per significant political actor. However I would stand by the claim that less than 1% of enciphered letters survive. I think one can guess at the least amount of enciphered letters there must have been e.g. on average significantly more than 1 letter per cipher key.