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And it will, definitely, happen. Just as one of the first uses of the modern computer (the Bletchley Park Bombe) was to break the symmetric key cryptography used by the Nazi military (Enigma and all that), so one of the first uses of a quantum computer will be to break the public key cryptography used by the military, government, bank, pharmaceutical and other systems in place today. But note the implication: breaking the codes will not simply mean that banks won’t be able to use it to exchange messages in confidence in the future but that all data encrypted using public key cryptography since it was invented (in the 1970s) will become visible.
From Schrodinger’s cash:
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Snippings 