Store challenge, signature as str/unicode for JSON serialization
Store challenge, signature as str/unicode for JSON serialization

NinjaMSP/crossbar,w1z2g3/crossbar,w1z2g3/crossbar,NinjaMSP/crossbar,w1z2g3/crossbar,w1z2g3/crossbar,w1z2g3/crossbar,w1z2g3/crossbar,NinjaMSP/crossbar,w1z2g3/crossbar