Digital Signature Verification

This paper discusses Fast Batch Verification for Digital Signature, Modified and Extended Batch Verification for Digital Signature and Identification of Bad Signature in Batchs.Firstly, we describe fast batch verifications for two typical digital signature schemes (DSA and RSA) and their variants (DSA* and RSA*). Moreover, this paper attacks and repairs these schemes. Secondly, a general technique of batch verification for equality of discrete logarithms is proposed. And this paper presents examples of batching threshold decryption schemes based on threshold versions of three popular cryptosystems-ELGamal, RSA and Paillier. The result is beneficial for producing more efficient schemes. Finally, identification of bad signatures is concerned in a sequence which is not validated using batching. The generic class of identification codes (id-codes) has been defined using the test-checking matrix A. The main construction of id-codes uses the so-called OR-checking matrix and its instantiation using mutually orthogonal Latin squares is described. The efficiency of identification doesn't depend on the distribution of bad signatures in a batch. And the number of tests depends on the number of bad signatures when the number of bad signatures doesn't exceed their identification capabilities.