pymsh 0.2.3

An implementation of multiset hashing

pymsh

pymsh is an MIT-licensed implementation of the incremental multi-set hashing (MSH) scheme based on Clarke et al. [1] (ASIACRYPT '03).

Specifically, it supports XOR-based hashing for fast updates; BLAKE2B is used as the underlying hash function.

Usage

Simple: initialise the MSH() class and call hash(...) for hashing multisets directly, or update(...) for incremental updates.

Examples:

from pymsh import pymsh

msh = pymsh.MSH()
m1 = msh.hash([b'apple', b'apple', b'banana'])
print(m1.hex()) # => Returns the multiset hash value of m1
msh.reset()
m2 = msh.hash([b'banana', b'apple', b'apple'])
print(m2.hex()) # => m2 will == m1

An example of the update function:

from pymsh import pymsh

msh = pymsh.MSH()
new_lst = [b'apple']
m3 = msh.hash(new_lst)
print(m3.hex())
m3 = msh.update(b'banana')
print(m3.hex())
m3 = msh.update(b'apple')
print(m3.hex()) # => Equivalent to m2 or m1 above

References

1. Clarke, D., Devadas, S., van Dijk, M., Gassend, B., Suh, G.E. (2003). "Incremental Multiset Hash Functions and Their Application to Memory Integrity Checking." In: Advances in Cryptology - ASIACRYPT. Lecture Notes in Computer Science, vol 2894. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-40061-5_12