Manually unbreakable cryptography

This article examines the concept of implementing modern cryptographic techniques in historical contexts before computers existed. It discusses the feasibility of manual RSA with smaller primes, the ADFGVX cipher as a precursor to modern symmetric encryption, and the potential of mechanical devices like DES or stream ciphers (e.g., PCG) in WWII-era settings. The author argues that methods considered weak today would have been unbreakable without computational power, while considering practical implementation challenges. The piece also references a 2020 paper breaking PCG, highlighting how modern computing changes cryptographic security.