Differential fault analysis (DFA) is a semi-invasive hardware attack that deliberately modifies a running program to make secret information leak. Unlike passive observation, it changes computation while cryptographic operations execute. section 13.2.2
DFA fits into a broader hierarchy of attacks against smart cards and secure elements:
- Non-invasive attacks observe the device without affecting it, as with differential power analysis. section 13.2.2
- Semi-invasive DFA uses heat, lasers, or similar techniques to alter execution without necessarily opening or destroying the chip. section 13.2.2
- Invasive attacks probe or modify circuitry inside the silicon and may damage the device. section 13.2.2
A fault in a cryptographic operation
Imagine targeting a smart card while it performs a cryptographic operation. A laser or burst of heat changes one step of execution; comparing the resulting behavior with normal operation can help leak the card’s key. section 13.2.2
