ccna and beyond

ccna and beyond.There are two known hash functions.Message Digest 5 (Message Digest5, MD5), which uses a 128-bit digest.Secure Hash Algorithm 256 (SHA-256), which uses a 256-bit digest.7.2.2 Integrity of MD5 and SHA-17.2.2.1 Message Digest 5 AlgorithmThe MD5 algorithm is a hashing algorithm developed by RonRivest and used in a variety of Internet applications today. MD5 is a one-way function, which makes it easy to compute a hash of a given input data, but it is not feasible to compute the input data based on only one hash value. MD5 is also conflict-resistant, which means that it is impossible to have two messages with the same hash. Essentially, MD5 is a complex sequence of simple binary operations (e.g., iso-or [XOR] and rotation) performed on the input data to produce a 128-bit digest. The main algorithm is based on a compression function that operates on blocks. The input to the algorithm is a block of data plus the feedback from the previous block. The 512-bit block is divided into 16 32-bit sub-blocks. These blocks are subsequently rearranged in a main loop containing four rounds of loops. The output of the algorithm is a set of four 32-bit blocks that are concatenated to form a single 128-bit hash value. The length of the message is also encoded into the digest. MD5 is based on an earlier algorithm: MD4O MD4 has been broken, and MD5 0 was previously considered by many cryptographic authorities to be less secure than SHA-1. These authorities considered MD5 to be less secure because of some non-critical weaknesses found in one of the construction blocks of MD5.7.222 Secure Hash AlgorithmThe National Institute of Standards and Technology (NIST) has developed the Secure Hash Algorithm (SHA), which is specified in the Secure Hash Standard (SHS). This algorithm is specified in the Secure Hash Standard (SHS). SHA.1, released in 1994, corrected an unpublished flaw in SHA. The design of SHA is very similar to the MD4 and MD5 hash functions developed by RonRivest.The SHA-1 algorithm generates a 160-bit message digest for messages less than 264 bits in length. This algorithm is slightly slower than MD5, but the longer message digest makes it more secure against brute force cracking and reverse attacks.NIST has published four additional hash functions in the SHA family, each with a longer digest.