What is Crypthography?


The word crytography comes from the Greek kryptós (hidden), graphein (writing) and -logia (study). That is to say, the art of hiding information from others by transforming it (encrypting it) into un unreadable format. This information can only by decrypted by using a special code (key).

As the Internet and other forms of electronic communication become more prevalent, electronic security is becoming increasingly important. Cryptography is used to protect e-mail messages, credit card information, and corporate data and that can be achieved by using cryptographic algorithms and authentication techniques.

During the last years, special efforts have been applied to achieve a great level of security. These efforts have increased security in some aspects, such as cryptographic algorithms and authentication techniques, etc. But many other security holes have appeared in these applications.


 What are the risks of a weak cryptographic system?


Unfortunately in this race for breaking private information, some hackers have shown that the weakest point in IT systems may not be the algorithms themselves, but the computer system where the information flows.

For example, we can have a very secure system to buy goods through the Internet but our computer could have been infected by a trojan that inspects the information we view, and, of course, the information we enter (such as our credit card numbers). Of more importance is that it can analyse the cryptographic algorithm and extract our public and private keys. When a hacker has our private key, all the security of the system is vanished.

This occurs, because in most systems, all security is held using only software installed in a device (such as a PC or a Network Computer) which is not tamper-proof. A solution for some of those situations is the use of Security Aided Modules (SAM), which is nothing but a piece of tamper-proof hardware, that performs all cryptographic functions and stores sensitive data, such as keys or other user-related information (i.e., credit card numbers).


 Improvements in cryptography


Security Hardware Modules, or also called Security Aided Modules (SAM), are devices where cryptographic operations are performed. They are supposed to be tamper-proof devices, with the secret keys stored and impervious to extraction of information about the keys, temporal data, or partial computations.

Therefore, SAMs behave like black boxes where data are entered and results obtained. Then. using a SAM, problems like the ones mentioned above about trojans could be minimized. Also, as it is a co-processor, it reduces the computational cost of the whole system.

SAMs systems allow to:

  • Auto-block/Auto-destruction: To avoid any success from brutal force attacks, SAMs should recognise if they are suffering such attack, and, if so, block themselves. If the attack is strong enough, the SAM can auto-destruct, erasing all stored information .

  • User authentication: PIN, password, or biometric pattern can ve hacked if entered in the user’s computer. Data should be, then, entered in the same SAM, avoiding using an external system, i.e., placing a keypad or a biometric sensor in the module. If this is not possible, at least all these data should be transmitted in a secure way.

  • SAMs implementations: In order to implement a Security Hardware Module, the designer can choose from among several possibilities: commercial tamper-proof module, such as smart cards; developing an ad-hoc microprocessor-based SAM or developing an ASIC, i.e., an Application Specific Integrated Circuit. Also, he has to study whether personal data should be taken by the user everywhere he goes (portability) or these data should be locked physically in some other place.




  • Data Protection
  • Integrity of Data
  • Authentication
  • Secure Network Communications
  • Digital Signature
  • Secure Certification
  • Secure e-Commerce
  • Secure e-Money
  • Secure e-Transactions


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Grup of Biometrics, Biosignals and Security (GB2S)