A method and system for generating a digital signature of a data item. A unique condition digest of at least two condition digests is iteratively processed in each iteration of a loop for a sufficient number of iterations to process all of the condition digests. Each iteration includes concatenating a reference digest with the unique condition digest of the iteration to generate a concatenand and hashing the concatenand to generate a hashed concatenand serving as the reference digest for the next iteration. Each unique condition digest is a different condition digest in each iteration. The regenerated reference digest of the last iteration is a last digest which is encrypted to generate a digital signature block that represents the data item and at least two conditions specified for the digital signature. The digital signature block includes the digital signature. The encrypting includes signing the last digest with the digital signature.