Password algorithm on a smart card application development (1)

Summary: over the past decade, the smart card, the rapid development of computing power, a smart card based on public key is widely applied in various fields.

2001 Borst summed up the smart card application of various password algorithm, and these algorithms.

For the past 10 years, smart card, the rapid development of computing power, a smart card based on public key is widely applied in various fields.

2001 Borst summed up the smart card application of various password algorithm, and these algorithms. Since then, about password algorithm attacks more and more, the more famous for MD5 and SHA-1 attacks and the other on the hash function attacks. In addition, less for people's attention and, like the A5/l (applied to GSM) and EO (applied to Bluetooth) such a stream cipher analysis techniques have also made significant progress. At the AES block cipher, adoption to guarantee security. Public-key cipher, RSA Security has also become a populated technology research.

1 message authentication codes

Message authentication code is actually one of the message itself redundant information, message authentication codes is to use the key pair to certified message to generate new data blocks and block encryption generated, it is necessary to protect the information it is one-to-one.

So the message authentication codes can effectively guarantee the integrity of the message, and sending messages to non-repudiation and cannot be forged. Message authentication code security depends on two things: first of all, the use of the encryption algorithm, the so-called digital signatures; Secondly, the question to the encrypted data blocks in the generated method.

Message authentication code does not support the reversibility, is many-to-one function, its fields from the message of arbitrary length, but the range is much less than the length of a message constitutes a bit string.

In theory, must present a different message to produce the same authentication code, so you have to find a sufficiently strong one-way and collision-free method is safe.

For message authentication code of the main target is to find a pair or pairs of collision message.

For existing methods of attack, and some can attack any type of hashing scheme, some only for specific hashing scheme. Since 2004 the MD5 algorithm was breached, SHA also face the risk of being compromised. Therefore, looking for a sufficiently secure one-way hash function has become a top priority, message authentication codes implementation also change.

2 block cipher

Group password in the password field is widely used, in addition to several work itself mode, it can be used to build a MAC, can also be used to build the hash function, pseudo-random function and so on.

Block cipher with a fast, easy to standardize and facilitate the implementation of hardware and software, etc., usually the information domain network security for data encryption, digital signature, authentication and key management core system, computer, communication and information system security field has the widest range of applications.

The first widespread use of block cipher algorithm is the DES algorithm.

DES since 1977 publication was supported by many organizations, departments, national cryptology workers also it in-depth analysis, it is by far the most widely used and most successful block cipher. DES of round Feistel network functions, 8 s-boxes, expansion, compression permutation, block replacement. The algorithm is simple, fast and decryption. But an obvious flaw is the s-box as a black box, therefore public long complained and suspected it has a trapdoor. Early iteration block cipher design center around DES, later on this basis have great development, there were numerous Feistel-password, DES design still shining with the essence of human design idea, its structure and parts are still being remembered as follow. But its key length is too short, only 56 bits, can't resist exhaustive key search attacks.

On a successful crack DES forced people to redesign the cipher algorithm.

IDEA is X.Lai and j.l.massey released in 1990, then known as PES, 1992 was renamed as the IDEA. IDEA is the first one does not use a Feistel network block cipher. IDEA of security design idea is: adopt the same clear space on three different group of operation that allows concealed, confusion and proliferation. IDEA is an outstanding representative of block cipher, and created a new class of design style. But the IDEA there are a large number of weak key, this key expansion algorithm is linear transformation, this also indicates the need to redesign the key expansion algorithm. Since then the NEA is a kind of IDEA-password.

Rijndael is the ultimate winner AES activity, has now become a replacement for DES United States new encryption standard.

Rijndael round function design based on wide-track strategy, this design strategy is for difference cryptanalysis and linear cryptanalysis, mainly includes two design criteria: first, select a smaller differential uniformity and high linearity of s-boxes; second, the appropriate choice of linear transformations, making fixed wheel number of towels s-box number as many as possible. If the differential characteristics (or linear approximation) in a round of the number of active s-boxes, the less the next round of the number of active s-boxes must be more. Wide-track policy maximum advantage is you can estimate the maximum difference algorithm characteristics of probability and the maximum probability of linear approximation, which you can assess the differential cryptanalysis algorithms for resistance and linear cryptanalysis. Following the activities of the United States call for AES, Europe in March 2000 launched a major programme, NESS1E aims to launch a series of security of the password module, keeping European research at the password's leadership and enhanced password in European industry as a European generation of encryption standard, Camellia algorithm with strong security, resistant to differential and linear cryptanalysis, etc. known attacks. Compared with the AES algorithm in a variety of Camellia hardware platform shows the equivalent encryptionSpeed. In addition to various software and hardware platforms, the efficiency of this notable characteristic, it's another feature is the small design of the hardware platform.

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