The evolution of cryptography and the methods of both hiding and revealing information has had an interesting path. In the early usage transposition ciphers such as the scytale were used, although transposition ciphers seem much less secure (especially for shorter messages) if the scrambling method is too simple and an intercepted message could be translated through a few well-placed key letters. For example, some word scrambles can be solved just by looking at the letters for a while. What I always wondered, though, is why substitution ciphers and transposition ciphers were the norm for so long without any real development past the basic forms.
The statement Singh made discussing how cryptanalysis would only evolve once a society had reached a sufficient level in several disciplines of math and linguistics cleared up a lot for me. Since there were no major breakthroughs in techniques such as frequency analysis until the Renaissance period, stronger ciphers weren’t needed. When it was realized that frequency analysis was being used to break ciphers, different methods of encryption like the Vigenère cipher were created to counter letter frequencies. When that method’s flaws were found, even stronger methods of encryption were developed.
Cryptographers and cryptoanalysts are, in a sense, an extremely smart predator and an extremely smart prey. Those who make ciphers are almost always a little bit ahead of those who try to break them, though, because they are able to see their encryptions’ weaknesses and adjust to hide their information before the cryptoanalysts come along to reveal it. Like many have said, cryptography is a constantly evolving field and also serves to inform us that no matter how secure something may seem, one should never bet the farm on its infallibility.