Keyed Hash Algorithms
Crytography, security-analysis, measures, processes and in this case an algorithm(s) set, that provides protection against modification of the hash. It does so by encrypting it, with secret key. One that both the sender and receiver must have for successful access, transmittal and retrieval, making sense of its content et al. there are always security and hacking risks, breaches and threats out there, pertaining to permissions, access, authorization, authentication and other protocols and procedures we use to safeguard our data, files, information and communications. This also rings true for prevention of hacking of hash values modifications etc.
There are two of these keyed hash algorithms in the .NET Framework, derived from System.Security.Cryptography. KeyedHashAlgorithm Namespace. These represents the abstract class from which all implementations of keyed hash algorithms must derive. Access, create and manage through the mscorlib (in mscorlib.dll) assembly.
According to industry definition:
(i) Key # 1: also called the HMACSHA1 Class, computes a Hash-based Message Authentication Code (HMAC) using the SHA1 hash function. Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe. HMACSHA1 accepts keys of any size, and produces a hash sequence of length 20 bytes.
(ii) Key # 2: MacTripleDES: this in actual fact, computes a Message Authentication Code (MAC) using TripleDES for the input data CryptoStream. MACTripleDES uses a key of length 16 or 24 bytes, and produces a hash sequence of length 8 bytes
It can tell whether a message sent over insecure channel has been altered or tampered with and pose a risk (sender/receiver share the same secret key) Any changes will cause a mismatch, if the codes both sides match, there is authentication.
Key Exam Points
- Review the relevant chapters pertaining to Fundamentals, User and Data Security
- For the exam, learn how to compute a keyed hash, what they are and what they do, how they can be used to improve security, integrity and lower risk.
- Work through the practical and hands-on programming study examples, exercises, lab-work, for Keyed Hash Algorithms, that help you to gain a better understanding and prowess on this topic.
- Take the practice test and review any of the Q&A Sample Multiple Choice Type as well as Application Questions
Related Terms
Hash, Encryption Key, Shared Secret.
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