Algorithm Matrix

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The table below presents a comparison of characteristics of the DES, TDEA and AES algorithms.

Comparison of PDS-Supported Ciphers
Block Size 64 bits 64 bits 128 bits
Key Size 64 bits 192 bits 1 128, 192 or 256 bits
Key Size minus parity 56 bits 2 168 bits 2 128, 192 or 256 bits
Effective Key Size 56 bits 112 bits 3 128, 192 or 256 bits
Performance OK 4 SLOW 4,5 BEST
Secure NO 6 YES (until ~2030) HIGHLY

1. TDEA is comprised of 3 unique DES keys.

2. Of the 64 bits in the key, 8 of those are parity bits, so the effective size of the DES key is 56 bits (and TDEA is effectively 168 bits).

3. TDEA at "168 effective" is further reduced due to meet in the middle (MITM) attacks.

4. Works with a 64 bit block size, so there are more cycles than AES.

5. Encrypts the block with key 1, then decrypts the encrypted block with key 2, and then re-encrypts the encrypted-then-decrypted block with key 3 (hence the TDEA).

6. With only 56 bits in the key, a brute force attack could "pretty quickly" guess all the possible keys, and thus would lead to the attacker being able to read your private information. This type of attack is not something that most people would be able to undertake, and you may not really care if all you are protecting is your access credentials to check out books at the local library. But for protecting more critical credentials, like those to your bank accounts, using DES would be strongly discouraged.

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