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1
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How can 3DES encryption use decryption in the middle step?
I have been reading about the 3DES algorithm and I cannot understand one part. In 3DES we do following operation: $$C=E[K_3,D[K_2,E[K_1,P]]].$$
Where $C$ is ciphertext, $P$ is plaintext, $E$ is DES ...
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Why do we use encrypt-decrypt-encrypt (EDE) in 3DES, rather than encrypting three times?
I'm wondering why we use encrypt-decrypt-encrypt sequence in 3DES with three keys instead of three times encryption with three different keys?
