Differential fault analysis is a type of side channel attack

Side channel attack

In cryptography, a side channel attack is any attack based on information gained from the physical implementation of a cryptosystem, rather than brute force or theoretical weaknesses in the algorithms...

 in the field of cryptography

Cryptography

Cryptography is the practice and study of techniques for secure communication in the presence of third parties...

, specifically cryptanalysis

Cryptanalysis

Cryptanalysis is the study of methods for obtaining the meaning of encrypted information, without access to the secret information that is normally required to do so. Typically, this involves knowing how the system works and finding a secret key...

. The principle is to induce faults—unexpected environmental conditions—into cryptographic implementations, to reveal their internal states.

For example, a smartcard containing an embedded processor

Secure cryptoprocessor

A secure cryptoprocessor is a dedicated computer on a chip or microprocessor for carrying out cryptographic operations, embedded in a packaging with multiple physical security measures, which give it a degree of tamper resistance....

 might be subjected to high temperature, unsupported supply voltage or current

Power supply

A power supply is a device that supplies electrical energy to one or more electric loads. The term is most commonly applied to devices that convert one form of electrical energy to another, though it may also refer to devices that convert another form of energy to electrical energy...

, excessively high overclocking

Overclocking

Overclocking is the process of operating a computer component at a higher clock rate than it was designed for or was specified by the manufacturer, but some manufacturers purposely underclock their components to improve battery life. Many people just overclock or 'rightclock' their hardware to...

, strong electric

Electric field

In physics, an electric field surrounds electrically charged particles and time-varying magnetic fields. The electric field depicts the force exerted on other electrically charged objects by the electrically charged particle the field is surrounding...

 or magnetic field

Magnetic field

A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...

s, or even ionizing radiation

Ionizing radiation

Ionizing radiation is radiation composed of particles that individually have sufficient energy to remove an electron from an atom or molecule. This ionization produces free radicals, which are atoms or molecules containing unpaired electrons...

 to influence the operation of the processor. The processor may begin to output incorrect results due to physical data corruption

Data corruption

Data corruption refers to errors in computer data that occur during writing, reading, storage, transmission, or processing, which introduce unintended changes to the original data...

, which may help a cryptanalyst deduce the instructions that the processor is running, or what its internal data state is.

For DES

DES

-Computing:* Data Encryption Standard* DirectShow Editing Services, an Application Programming Interface-Medical:* Diethylstilbestrol, a synthetic estrogen and the origin of the phrase "DES daughter"* DES gene, which encodes the Desmin protein...

 and Triple DES

Triple DES

In cryptography, Triple DES is the common name for the Triple Data Encryption Algorithm block cipher, which applies the Data Encryption Standard cipher algorithm three times to each data block....

, about 200 single-flipped bits are necessary to obtain a secret key

Key (cryptography)

In cryptography, a key is a piece of information that determines the functional output of a cryptographic algorithm or cipher. Without a key, the algorithm would produce no useful result. In encryption, a key specifies the particular transformation of plaintext into ciphertext, or vice versa...

.