On the probability and impact of collisions on soft input decryption

Soft Input Decryption has been introduced earlier as a method for detection and correction of bit errors over erroneous channels. It uses the cryptographic checksums for the correction of channel errors using the additional soft information available from the channel decoders, such as MAP. However there is a probability of collisions associated with the cryptographic hash codes. As a result of the collisions, the results of the verification of the cryptographic hash codes are not authentic. In this work the probability of hash collisions and their impact on the method of Soft Input Decryption is discussed. Analytical solutions are presented and are compared with the experimental results.