On the Security of the Cha-Ko-Lee-Han-Cheon Braid Group Public Key Cryptosystem

We show that a number of cryptographic protocols using non-commutative semigroups including the Cha-Ko-Lee-Han-Cheon braid group public-key cryptosystem and related public-key cryptosystems such as the Shpilrain-Ushakov public-key cryptosystems are based on the MSCSP.