In cryptography, etc. code authenticity validation message based on Moroccan storage (HMAC), the structure of the certain to calculate the code message authentication (MAC) that includes a function Moroccan maker encryption in combination with a password key. HMAC is like any MAC, you can integrity of data and authenticity of a message simultaneously examine. Each function Moroccan maker encryption, such as MD5 or SHA-1, etc. can be used to calculate the HMAC. This way, the algorithm of the MAC result. HMAC-MD5 or HMAC-SHA1 is called. Power HMAC encryption to the strength of the encryption function, the UAE construction rates. the size of the bit length of the output of the UAE, it and the size and quality of the encryption key depends on.
a function, the UAE builder, duplicate, etc. messages, into blocks of a given size does the split function and compression on them, repeat. For example, MD5 and SHA-1, etc. on blocks of 512-bit act. The size of the output of HMAC with the size function, the UAE construction rates in it is the same. (In the case of MD5 SHA-1, the 128 or 160 bit). However, this size can be, if necessary, short.