3DES (Triple-DES)
Symmetrical encryption algorithm with an effective key length of 168 bits. 3DES utilizes three DES keys of 56 bits each. The plaintext is encrypted with the first key, decrypted with the second, and encrypted again with the third. The procedure is regarded as secure, but is not particularly performant. For a time, it was suspected that the consecutive rounds of encryption involved might form a mathematical group, which would have significantly weakened the procedure. This suspicion has meanwhile been refuted.
