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Vernam Cipher and Perfect secrecy

Here we see a perfectly secure cryptosystem which was developed by Gilbert Vernam in 1918. Vernam sees a trade off between security and convenience, and the trade-off has to do with the length of the key tape as its security depends on the fact that the key is used only once.

About the experiment:

The main idea is to realize that any perfectly secure encryption scheme (and not just the One-Time Pad) requires the keyspace to be at least as large as the message space, and is therefore impractical