how many bits make up the effective des key
TripleDES key sizes - .NET vs Wikipedia. Wikipedia does not say TripleDES supports 56 bit keys. The keying options talk about triple-length keys and double-length keys, the latter reduces the key size to 112 bits. The effective key size for the original DES is 56 bit. Such a key is constructed from 64 bit input though, where 8 bits remain unused. The triple-length key option thus works with a three times 56 bit (=168) constructed from three times 64 bit (=192 bit) and the double-length option works with two times 56 bit keys (=112) constructed from two times 64 bit (=128).