Improved speed Digital Signature Algorithm based on modular inverse

DSA(Digital Signature Algorithm) algorithm is widely used in the digital signature fields. With the arrival of the era of big data, it has been put forward higher requirements for the operation speed of variety of digital signature algorithm. An improved speed algorithm isDSA (Improved Speed DSA) is presented, which is based on the idea of avoiding the complex and time-consuming modular inverse. In isDSA, it modifies the component s of the signature, cancels w of the verification, modifies u₁ and u₂ of the verification, and in the meantime the independent messages operations are pre-computed and saved. Using the same fast algorithm for large numbers, isDSA and DSA are simulated. Setting the length of modulus p 1024bits, the simulation result shows that the signature speeds of isDSA and DSA with pre-computation are same - less than 1ms because of no complicated operations. And the verification speed of isDSA is increased by 25.40% than DSA. And the security of isDSA and DSA is compared and analyzed, it proves that isDSA has the same security strength with DSA.