Editing Related-key attack (section)

{{redirect|Related key|the concept in music theory|Closely related key}}
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In [[cryptography]], a '''related-key attack''' is any form of [[cryptanalysis]] where the attacker can observe the operation of a [[cipher]] under several different [[key (cryptography)|keys]] whose values are initially unknown, but where some mathematical relationship connecting the keys is known to the attacker. For example, the attacker might know that the last 80 bits of the keys are always the same, even though they don't know, at first, what the bits are.