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Symmetric Key
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One key is shared by two users both encryption & decryption (substiution cipher, aes, des)
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Assymetric
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Public and Private Key
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Substitution Ciper
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Mono-alphabetic cipher 2^n/2
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Diffie-Helman Exchange
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Exchanging secret keys over insecure medium. Known large prime and base shared and a secret integer
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DES
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56-bit symmetric key, 64bit plain text US standard
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AES
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Replaces DES 128 bit
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Axor0, AxorA
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A, 0
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Main Sec. Probs In Mobile?
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Config. management, excessive privleges, privacy violations, poor session management
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Most problematic part in mobil apps?
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Android abstraction layer
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Preventing replay attacks?
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Use a nonce
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Pros of Symmetric Keys
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No worry of replay or man in the middle attacks
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Agreement on shared key
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diffie helman or KDC
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Certificate Auth
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Binds pub key to part. entity. E registers with CA. When Alice wants bobs pub key, get the certificate, apply CA pub key and get bobs pub key.
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Symmetric and Public Key Problems
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Sym: establish shared key? (deffie-helman, KDC), Public Key(Man in middle) use CA
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factors that affect power
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power affects temp, but energy doesn't
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equations
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power/area proportional to temp
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associations
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higher current implies high power which increases cpu frequency
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thermal runaway
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power -> temp -> resistance decrease -> current increase I (cycle)
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energy
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asffects battery life, power * time = E
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energy harvesting
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solar, wind -> high capacity, low leakage (low discharge), low capacity, high leakage (quick discharge), appliance
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ID vs Auth
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Auth = username + pass, ID = passwd & something like biometric
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Data injection
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sending false radio signal to pace maker and inducing heart attack
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Threat Model/Attack model
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What the system thinks about the model. Believes attacker is much more powerful than he actually is. Attack model attacker believes it knows a lot about the system
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Key establishment in physi. sec.
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Done using human body
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Ways to fool machine
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brute force feature guess, generate signal (generative), evasion, poison
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Evasion attack
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create points to gain access without getting caught, alter features
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Poison attack
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attacker can see the training set, injects their own data at key points, skews the lines
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Biometric signals
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Signals that don't change like fingerprints
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Physiological signals
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hard because constantly changing
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Hardening Technique
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instead of line, have piecewise curves, or instead of line use polygon(polytope)
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Internet Control Protocol Messages
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agent advertisement, agent solicitation, registration request, registration reply
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Foreign Agent
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Consumes less ip addresses than mobile host
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security performance tradeoff
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Increase in security strength -> hardening Hardening implies more difficult classification boundaries May increase False positives or negatives How to find a balance between security strength and performance? Multi-objective optimization problem
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Challenges of CPS
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hard to know how many sensors to use, what data to collect
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Cyber Physical Systems
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embedding sensors into physical devices
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Human to Human interaction
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person a thinks about a color red and that dot is displayed to another person in another country
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3 charactertistics of IOT devices
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anytime, anything, any place connetion
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USN application layer
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where apps are built to perform tasks using the sensors through middleware
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middleware (Drivers)
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allows you to build apps on top of iot sensors
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sensor networking layer (bottom)
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sensors are launched in environment and report to usn
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Difference between gps and tower based location management?
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gps needs clear line of sight and is more accurate. Tower based management is bad if you're not near tower, accessibility is less than gps.
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what is iot
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Network of Physical Objects embedded systems with electronics, software, sensors enable objects to exchange data with manufacturer, operator, other devices through network infrastructure allow remote control direct integration computer + physical world Result: automation in all fields
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Challenges in medical apps
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resource constraints in sensors, poor software dev support, real-time requirements for health apps
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CUDA basics
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Terminology Host – The CPU and its memory (host memory) Device – The GPU and its memory (device memory
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__global__
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As before, __global__ is a CUDA C keyword meaning — add() will execute on the device — add() will be called from the host
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memory management
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Host and device memory are distinct entities — Device pointers point to GPU memory May be passed to and from host code May not be dereferenced from host code — Host pointers point to CPU memory May be passed to and from device code May not be dereferenced from device code
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