Crypto1 is a proprietary
encryption
In cryptography, encryption is the process of encoding information. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Ideally, only authorized parties can dec ...
algorithm (
stream cipher
stream cipher is a symmetric key cipher where plaintext digits are combined with a pseudorandom cipher digit stream ( keystream). In a stream cipher, each plaintext digit is encrypted one at a time with the corresponding digit of the keystream ...
) and authentication protocol created by
NXP Semiconductors
NXP Semiconductors N.V. (NXP) is a Dutch semiconductor designer and manufacturer with headquarters in Eindhoven, Netherlands. The company employs approximately 31,000 people in more than 30 countries. NXP reported revenue of $11.06 billion in 2 ...
for its
MIFARE
MIFARE is the NXP Semiconductors-owned trademark of a series of integrated circuit (IC) chips used in contactless smart cards and proximity cards.
The brand name covers proprietary solutions based upon various levels of the ISO/IEC 14443 Type A ...
Classic
RFID
Radio-frequency identification (RFID) uses electromagnetic fields to automatically identify and track tags attached to objects. An RFID system consists of a tiny radio transponder, a radio receiver and transmitter. When triggered by an electroma ...
contactless smart cards Contactless may refer to:
* Contactless smart card
* Proximity card, a contactless integrated circuit device used for security access or payment systems
* Contactless payment, systems which use RFID for making secure payments
* MasterCard Contactl ...
launched in 1994. Such cards have been used in many notable systems, including
Oyster card
The Oyster card is a payment method for public transport in London (and certain areas around it) in England, United Kingdom. A standard Oyster card is a blue credit-card-sized stored-value contactless smart card. It is promoted by Transport ...
,
CharlieCard
The CharlieCard is a contactless smart card used for fare payment for transportation in the Boston area. It is the primary payment method for the Massachusetts Bay Transportation Authority (MBTA) and several regional public transport systems in ...
and
OV-chipkaart
The OV-chipkaart (short for ''openbaar vervoer chipkaart'', meaning ''public transport chipcard'') is a contactless smart card system used for all public transport in the Netherlands. First introduced in the Rotterdam Metro in April 2005, it has ...
.
By 2009, cryptographic research had
reverse engineered
Reverse engineering (also known as backwards engineering or back engineering) is a process or method through which one attempts to understand through deductive reasoning how a previously made device, process, system, or piece of software accompli ...
the cipher and a variety of attacks were published that effectively broke the security.
NXP responded by issueing "hardened" (but still backwards compatible) cards, the MIFARE Classic EV1. However, in 2015 a new attack rendered the cards insecure, and NXP now recommends migrating away from MIFARE Classic.
Technical description
Crypto1 is a
stream cipher
stream cipher is a symmetric key cipher where plaintext digits are combined with a pseudorandom cipher digit stream ( keystream). In a stream cipher, each plaintext digit is encrypted one at a time with the corresponding digit of the keystream ...
very similar in its structure to its successor, Hitag2. Crypto1 consists of
* a 48-bit
linear feedback shift register
In computing, a linear-feedback shift register (LFSR) is a shift register whose input bit is a linear function of its previous state.
The most commonly used linear function of single bits is exclusive-or (XOR). Thus, an LFSR is most often a s ...
for the state of the cipher,
* a two-layer 20-to-1 nonlinear function used to generate the keystream, and
* a 16-bit LFSR which is used during the authentication phase as a
pseudo random number generator
The usual operation of Crypto1 and Hitag2 ciphers uses nonlinear feedback only during the initialization/authentication stage, switching to operation as a LFSR with a nonlinear output filter (filter generator) for the rest of the communications.
See also
*
KeeLoq
KeeLoq is a proprietary hardware-dedicated block cipher that uses a non-linear feedback shift register (NLFSR). The uni-directional command transfer protocol was designed by Frederick Bruwer of Nanoteq (Pty) Ltd., the cryptographic algorithm was ...
References
External links
* Radboud Universiteit Nijmegen press releas
PDF(in English)
* Details of Mifare reverse engineering by Henryk Plöt
PDF(in German)
Stream ciphers
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