Editing Stream cipher attacks (section)

{{Short description|Methods to break a stream cipher}}
{{Multiple issues|
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[[Stream cipher]]s, where [[plaintext]] bits are combined with a cipher bit stream by an exclusive-or operation ([[xor]]), can be very secure if used properly.{{citation needed|date=July 2019}} However, they are vulnerable to attacks if certain precautions are not followed:

*keys must never be used twice
*valid decryption should never be relied on to indicate authenticity