The symmetric ciphers

[Philipp Klaus Krause]

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Am 30.10.2013 18:39, schrieb Robert J. Hansen:
>> Well, here's a (rough, and maybe naive) explanation of why I
>> assumed that the effort is at least max(a, b):
> 
> If you first encrypt with ROT10 and then with ROT16, the final
> strength is not the maximum of (ROT10, ROT16).  You may think
> that's a silly example, and I grant that it is, but it illuminates
> the point pretty well and avoids a lot of difficult math.

But ROT10 and ROT16 fail the condition that breaking them should be
substancially harder than applying them.

Philipp

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