Editing Passive attack (section)

{{Short description|Attempting to break a system solely based upon ciphertext}}
A '''passive attack''' on a [[cryptosystem]] is one in which the cryptanalyst cannot interact with any of the parties involved, attempting to break the system solely based upon observed data (i.e. the [[ciphertext]]).<ref name="geeks"/><ref name="book1"/> This can also include [[known plaintext attack]]s where both the [[plaintext]] and its corresponding ciphertext are known.

While active attackers can interact with the parties by sending data, a passive attacker is limited to intercepting communications (eavesdropping), and seeks to decrypt data by interpreting the transcripts of authentication sessions.<ref name="nlhb"/><ref name="manets"/> Since passive attackers do not introduce data of their own, they can be difficult to detect.<ref name="meshnets"/>

While most classical ciphers are vulnerable to this form of attack, most modern ciphers are designed to prevent this type of attack above all others.