Multi-Blockchain Post-Quantum Signatures (MBPQS) is a hash-based post-quantum secure cryptographic digtal signature scheme specifically designed for multi-chain blockchain systems. The scheme is designed for private/consortium blockchain where orderers are predefined network peers, and sign blocks in segregated chains (channels).

The parameters for MBPQS are as following:

• n, chosen from {32,64}: security parameter in bytes. For n=32, SHA-256 is used throughout the scheme, and for n=64, SHA-512 is used.
• w, chosen from {4,16,256}: Winternitz parameter.
• rootH, integer < 20: height of the root tree, defines the maximum amount of channels which can be added (which is 2^rootH).
• chanH, integer < 2^32: height of the initial chain tree in a channel.
• gf, integer < (2^32-chanH): growing factor for subsequent chain trees relative to the previous chain tree in the channel. gf=0 results in no relative growth of chain trees.

This code is meant to showcase the workings of MBPQS, cross-validation, and experimenting. Do NOT use this code any software deployment as cryptographic code requires careful consideration of the specific deployment environment.

go get -u github.com/Breus/mbpqs

The scheme design uses ideas from XMSS-T to reach quantum-resistance, and the ChainTree structure from BPQS.

The implementation of WOTS+ (including multi-target resistance from WOTS-T) and parts of the XMSS tree generation, including the corresponding unit tests, are taken from Go-XMSS-MT from Bas Westerbaan.