TAILIEUCHUNG - Why (Special Agent) Johnny (Still) Can’t Encrypt: A Security Analysis of the APCO Project 25 Two-Way Radio System

In addition to its numerical representation, digital data has a physical representation. For example, the bits in a hard disk are magnetic impulses on platters that can be read with analog sensors. Network wires contain electric signals that represent network packets and keyboard cables contain electric signals that represent which keys were pressed. A computer converts the electric signals to a digital representation. Digital photography and video are a digital representation of the light associated with physical objects. Digital data can be stored on many mediums and each has different properties that determine how long the data will reside. For example, data will reside on a keyboard. | Why Special Agent Johnny Still Can t Encrypt A Security Analysis of the APCO Project 25 Two-Way Radio System Sandy Clark Travis Goodspeed Perry Metzger Zachary Wasserman Kevin Xu Matt Blaze University of Pennsylvania APCO Project 25 P25 is a suite of wireless communications protocols used in the US and elsewhere for public safety two-way voice radio systems. The protocols include security options in which voice and data traffic can be cryptographically protected from eavesdropping. This paper analyzes the security of P25 systems against both passive and active adversaries. We found a number of protocol implementation and user interface weaknesses that routinely leak information to a passive eavesdropper or that permit highly efficient and difficult to detect active attacks. We introduce new selective subframe jamming attacks against P25 in which an active attacker with very modest resources can prevent specific kinds of traffic such as encrypted messages from being received while emitting only a small fraction of the aggregate power of the legitimate transmitter. We also found that even the passive attacks represent a serious practical threat. In a study we conducted over a two year period in several US metropolitan areas we found that a significant fraction of the encrypted P25 tactical radio traffic sent by federal law enforcement surveillance operatives is actually sent in the clear in spite of their users belief that they are encrypted and often reveals such sensitive data as the names of informants in criminal investigations. 1 Introduction APCO Project 25 16 also called P25 is a suite of digital protocols and standards designed for use in narrowband short-range VHF and UHF land-mobile wireless two-way communications systems. The system is intended primarily for use by public safety and other government users. The P25 protocols are designed by an international consortium of vendors and users centered in the United States coordinated by the Association of .

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