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On 08/09/2018 12:28 PM, Steve Pointer wrote:<br>
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<div style="font-family:Arial;">Take two large prime numbers at
random and multiply them together.<br>
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<div style="font-family:Arial;">Then with the result are you able
to establish the prime numbers which made them? easily? without
brute forcing?<br>
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<br>
Other answers are also going into details of public key
cryptography. But you don't need to.<br>
<br>
Plain old symmetric algorithms (good ones, such as AES) resist
known-plaintext attacks. They are very specifically designed to do
so: Give someone plaintext and matching AES cyphertext and it is NOT
feasible for that person to deduce the key.<br>
<br>
-kb<br>
<br>
P.S. Remember, public key cryptography is slow and cumbersome. It is
NOT used to encrypt big messages. It is used to encrypt little
messages, such as an AES key that was used for the rest of the
message.<br>
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