Published in Military & Aerospace Electronics
ASHBURN, Va. – Cryptography forms the foundation of many aspects of trusted computing. This article considers recent algorithms and cryptographic attacks, as well as some future directions for cryptography in deployed embedded systems.
This article provides a foundational understanding of the context of cryptographic algorithms, and delves into the details of secure hashing, common secure hashing algorithms, and some trusted computing applications of secure hashing.
Today there are three general categories of cryptographic algorithms that are common in trusted computing: secure hashing, symmetric cryptography, and asymmetric cryptography.
Hashing takes a relatively large piece of data and generates a relatively small unique value from that data. Given a large amount of data, if even one bit of the input data is changed, the resulting hash will change by a large amount and in a deterministic but unpredictable way. Cryptographic algorithms that use symmetric cryptography employ the same key to encrypt and decrypt the data.
Symmetric algorithms take data and encrypt them to be mathematically infeasible to extract the original information from the cipher text without the key. One key encrypts and decrypts to ensure the secrecy of that key, and so ensures the secrecy of the protected data.
In contrast, the third type of algorithm, asymmetric cryptography, uses a pair of keys. One is private and always should remain secret, while the other can be shared freely.
Asymmetric cryptography has uses like signing data, since it can prove who generated the data. Asymmetric cryptography also is for key agreement protocols to enable secure agreement on a shared secret key over an open network.