Soft correction and verification of the messages protected by cryptographic check values

The enhanced version of Soft Input Decrypion (SID) method for the correction of the messages secured by their cryptographic check values (digital signatures and/or MACs and H-MACs) are presented. The soft output values of SISO convolutional decoder (so called |L|-values) which are driven to the input of decryptor are now used in a more efficient way. By introducing the decision threshold, the process of message verification in decryptor becomes less strict, giving in that way extra benefits in processing speed and the method efficiency. The aspect of “false verification” of the message is also considered with regard to the value of the threshold. The results of simulations are presented as well, showing a significant improvement of the new method.