In the IETF RFC draft named "SM2 Digital Signature Algorithm" a signature algorithm is specified. The RFC does however not mention why this signature algorithm has been defined. Nor does it specify what the advantages of this scheme are over ECDSA. It seems that SM2 is the preferred EC signature format in China.
So the two related questions are:
- Why was SM2 defined?
- What are the (operational) differences compared to ECDSA?
Note that there seems to be a set of SM2 Elliptic Curve domain parameters defined as well.
[SM2 Algorithms Parameters] linked in the draft (and found on Wayback machine), here are the domain parameters:
y^2 = x^3 + ax + b p =FFFFFFFE FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF 00000000 FFFFFFFF FFFFFFFF a =FFFFFFFE FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF 00000000 FFFFFFFF FFFFFFFC b = 28E9FA9E 9D9F5E34 4D5A9E4B CF6509A7 F39789F5 15AB8F92 DDBCBD41 4D940E93 n = FFFFFFFE FFFFFFFF FFFFFFFF FFFFFFFF 7203DF6B 21C6052B 53BBF409 39D54123 Gx = 32C4AE2C 1F198119 5F990446 6A39C994 8FE30BBF F2660BE1 715A4589 334C74C7 Gy = BC3736A2 F4F6779C 59BDCEE3 6B692153 D0A9877C C62A4740 02DF32E5 2139F0A0