Mathematical optimization of decrypting algorithm for soft input decryption

In this work, the strategy for correction of bits using Soft Input Decryption is analyzed. Soft Input Decryption is used for correction of cryptographic check values, which are very fragile when they are transmitted over noisy channels: only one wrong bit at input of the decryptor causes about 50% of errors at output of the decryptor. Soft Input Decryption corrects incorrect bits of cryptographic check values in most of cases using combination of SISO channel decoding and decrypting. Soft Input Decryption is an iterative process and therefore it is needed to minimize duration of iterations. This paper suggests an algorithm for optimization of Soft Input Decryption, which enables restriction of needed computing time of the Soft Input Decryption algorithm. Suggested optimization is performed for ECDSA digital signatures.