What are the threats ? disclosure Confidentiality:unauthorized disclosure of information sender receiver modification Integrity:unauthorized modification of information Authenticity:unauthorized use of service
Whats inside a smart card ? CPU RAM test logic ROM EEPROM serial i/o interface security logic databus
Smart card security evaluations logical analysis: software internal analysis: hardware side channel analysis: both hw and sw
Logical analysis Communication Functional testing Protocol analysis Code review
Timing attack on RSA RSA principle: –Key set e,d,n –Encipherment: C = M e mod n –Decipherment: M = C d mod n RSA-implementation (binary exponentiation) –M := 1 –For i from t down to 0 do: M := M * M If d i = 1, then M := M*C
Differential Power Analysis Assume power consumption relates to hamming weight of data Subtract traces with high and low hamming weight Resulting trace shows hamming weight and data manipulation
Fault injection on smart cards Change a value read from memory to another value by manipulating the supply power: Threshold of read value A power dip at the moment of reading a memory cell
Differential Fault Analysis on RSA Efficient implementation splits exponentiation: d p = d mod (p-1) d q = d mod (q-1) K = p -1 mod q M p = C d p mod p M q = C d q mod q M = C d mod n = ( ( (M q - M p )*K ) mod q ) * p + M p
DFA on CRT Inject a fault during CRT that corrupts M q : M q is a corrupted result of M q computation M = ( ( (M q - M p )*K ) mod q ) * p + M p subtract M and M: M - M = (((M q - M p )*K) mod q)*p - (((M q - M p )*K) mod q)*p = (x 1 -x 2 )*p compute Gcd( M-M, n ) = Gcd( (x 1 -x 2 )*p, p*q ) = p compute q = n / p
Conclusions Smart cards can be broken by advanced analysis techniques. Users of security systems should think about: –What is the value of our secrets? –What are the risks (e.g. fraud, eavesdropping) –What are the costs and benefits of fraud? Perfect security does not exist!
For information: TNO Evaluation Centre Marc Witteman PO-Box 5013 2600 GA Delft, The Netherlands Phone:+31 15 269 2375 Fax:+31 15 269 2111 E-mail:email@example.com E-mail:firstname.lastname@example.org
Your consent to our cookies if you continue to use this website.