What is the maximum number of different keys that can be used when encrypting with Triple DES?

The correct answer is C. 3. Triple DES (3DES) applies the DES algorithm three times and supports up to 3 independent keys (K1, K2, K3), giving a maximum key size of 3 × 56 = 168 effective bits. The three keying options are: (1) all three keys different (strongest), (2) K1 = K3 but K2 different (2-key…

Submitted by daniela_cl· Apr 18, 2026Cryptography

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3% (1)
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C
87% (34)
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Explanation

Triple DES (3DES) applies the DES algorithm three times and supports up to 3 independent keys (K1, K2, K3), giving a maximum key size of 3 × 56 = 168 effective bits. The three keying options are: (1) all three keys different (strongest), (2) K1 = K3 but K2 different (2-key 3DES), and (3) all keys identical (equivalent to single DES, weakest). The maximum number of different keys is therefore 3.

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#Triple DES#3DES#Cryptographic keys#Encryption algorithm

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