--- /dev/null
+package sm2
+
+import (
+ "crypto/elliptic"
+ "math/big"
+ "sync"
+)
+
+/** 学习标准库p256的优化方法实现sm2的快速版本
+ * 标准库的p256的代码实现有些晦涩难懂，当然sm2的同样如此，有兴趣的大家可以研究研究，最后神兽压阵。。。
+ *
+ * ━━━━━━animal━━━━━━
+ * ┏┓ ┏┓
+ * ┏┛┻━━━┛┻┓
+ * ┃ ┃
+ * ┃ ━ ┃
+ * ┃ ┳┛ ┗┳ ┃
+ * ┃ ┃
+ * ┃ ┻ ┃
+ * ┃ ┃
+ * ┗━┓ ┏━┛
+ * ┃ ┃
+ * ┃ ┃
+ * ┃ ┗━━━┓
+ * ┃ ┣┓
+ * ┃ ┏┛
+ * ┗┓┓┏━┳┓┏┛
+ * ┃┫┫ ┃┫┫
+ * ┗┻┛ ┗┻┛
+ *
+ * ━━━━━Kawaii ━━━━━━
+ */
+
+type sm2P256Curve struct {
+ RInverse *big.Int
+ *elliptic.CurveParams
+ a, b, gx, gy sm2P256FieldElement
+}
+
+var initonce sync.Once
+var sm2P256 sm2P256Curve
+
+type sm2P256FieldElement [9]uint32
+type sm2P256LargeFieldElement [17]uint64
+
+const (
+ bottom28Bits = 0xFFFFFFF
+ bottom29Bits = 0x1FFFFFFF
+)
+
+func initP256Sm2() {
+ sm2P256.CurveParams = &elliptic.CurveParams{Name: "SM2-P-256"} // sm2
+ A, _ := new(big.Int).SetString("FFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF00000000FFFFFFFFFFFFFFFC", 16)
+ //SM2椭 椭 圆 曲 线 公 钥 密 码 算 法 推 荐 曲 线 参 数
+ sm2P256.P, _ = new(big.Int).SetString("FFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF00000000FFFFFFFFFFFFFFFF", 16)
+ sm2P256.N, _ = new(big.Int).SetString("FFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFF7203DF6B21C6052B53BBF40939D54123", 16)
+ sm2P256.B, _ = new(big.Int).SetString("28E9FA9E9D9F5E344D5A9E4BCF6509A7F39789F515AB8F92DDBCBD414D940E93", 16)
+ sm2P256.Gx, _ = new(big.Int).SetString("32C4AE2C1F1981195F9904466A39C9948FE30BBFF2660BE1715A4589334C74C7", 16)
+ sm2P256.Gy, _ = new(big.Int).SetString("BC3736A2F4F6779C59BDCEE36B692153D0A9877CC62A474002DF32E52139F0A0", 16)
+ sm2P256.RInverse, _ = new(big.Int).SetString("7ffffffd80000002fffffffe000000017ffffffe800000037ffffffc80000002", 16)
+ sm2P256.BitSize = 256
+ sm2P256FromBig(&sm2P256.a, A)
+ sm2P256FromBig(&sm2P256.gx, sm2P256.Gx)
+ sm2P256FromBig(&sm2P256.gy, sm2P256.Gy)
+ sm2P256FromBig(&sm2P256.b, sm2P256.B)
+}
+
+func P256Sm2() elliptic.Curve {
+ initonce.Do(initP256Sm2)
+ return sm2P256
+}
+
+func (curve sm2P256Curve) Params() *elliptic.CurveParams {
+ return sm2P256.CurveParams
+}
+
+// y^2 = x^3 + ax + b
+func (curve sm2P256Curve) IsOnCurve(X, Y *big.Int) bool {
+ var a, x, y, y2, x3 sm2P256FieldElement
+
+ sm2P256FromBig(&x, X)
+ sm2P256FromBig(&y, Y)
+
+ sm2P256Square(&x3, &x) // x3 = x ^ 2
+ sm2P256Mul(&x3, &x3, &x) // x3 = x ^ 2 * x
+ sm2P256Mul(&a, &curve.a, &x) // a = a * x
+ sm2P256Add(&x3, &x3, &a)
+ sm2P256Add(&x3, &x3, &curve.b)
+
+ sm2P256Square(&y2, &y) // y2 = y ^ 2
+ return sm2P256ToBig(&x3).Cmp(sm2P256ToBig(&y2)) == 0
+}
+
+func zForAffine(x, y *big.Int) *big.Int {
+ z := new(big.Int)
+ if x.Sign() != 0 || y.Sign() != 0 {
+ z.SetInt64(1)
+ }
+ return z
+}
+
+func (curve sm2P256Curve) Add(x1, y1, x2, y2 *big.Int) (*big.Int, *big.Int) {
+ var X1, Y1, Z1, X2, Y2, Z2, X3, Y3, Z3 sm2P256FieldElement
+
+ z1 := zForAffine(x1, y1)
+ z2 := zForAffine(x2, y2)
+ sm2P256FromBig(&X1, x1)
+ sm2P256FromBig(&Y1, y1)
+ sm2P256FromBig(&Z1, z1)
+ sm2P256FromBig(&X2, x2)
+ sm2P256FromBig(&Y2, y2)
+ sm2P256FromBig(&Z2, z2)
+ sm2P256PointAdd(&X1, &Y1, &Z1, &X2, &Y2, &Z2, &X3, &Y3, &Z3)
+ return sm2P256ToAffine(&X3, &Y3, &Z3)
+}
+
+func (curve sm2P256Curve) Double(x1, y1 *big.Int) (*big.Int, *big.Int) {
+ var X1, Y1, Z1 sm2P256FieldElement
+
+ z1 := zForAffine(x1, y1)
+ sm2P256FromBig(&X1, x1)
+ sm2P256FromBig(&Y1, y1)
+ sm2P256FromBig(&Z1, z1)
+ sm2P256PointDouble(&X1, &Y1, &Z1, &X1, &Y1, &Z1)
+ return sm2P256ToAffine(&X1, &Y1, &Z1)
+}
+
+func (curve sm2P256Curve) ScalarMult(x1, y1 *big.Int, k []byte) (*big.Int, *big.Int) {
+ var scalarReversed [32]byte
+ var X, Y, Z, X1, Y1 sm2P256FieldElement
+
+ sm2P256FromBig(&X1, x1)
+ sm2P256FromBig(&Y1, y1)
+ sm2P256GetScalar(&scalarReversed, k)
+ sm2P256ScalarMult(&X, &Y, &Z, &X1, &Y1, &scalarReversed)
+ return sm2P256ToAffine(&X, &Y, &Z)
+}
+
+func (curve sm2P256Curve) ScalarBaseMult(k []byte) (*big.Int, *big.Int) {
+ var scalarReversed [32]byte
+ var X, Y, Z sm2P256FieldElement
+
+ sm2P256GetScalar(&scalarReversed, k)
+ sm2P256ScalarBaseMult(&X, &Y, &Z, &scalarReversed)
+ return sm2P256ToAffine(&X, &Y, &Z)
+}
+
+var sm2P256Precomputed = [9 * 2 * 15 * 2]uint32{
+ 0x830053d, 0x328990f, 0x6c04fe1, 0xc0f72e5, 0x1e19f3c, 0x666b093, 0x175a87b, 0xec38276, 0x222cf4b,
+ 0x185a1bba, 0x354e593, 0x1295fac1, 0xf2bc469, 0x47c60fa, 0xc19b8a9, 0xf63533e, 0x903ae6b, 0xc79acba,
+ 0x15b061a4, 0x33e020b, 0xdffb34b, 0xfcf2c8, 0x16582e08, 0x262f203, 0xfb34381, 0xa55452, 0x604f0ff,
+ 0x41f1f90, 0xd64ced2, 0xee377bf, 0x75f05f0, 0x189467ae, 0xe2244e, 0x1e7700e8, 0x3fbc464, 0x9612d2e,
+ 0x1341b3b8, 0xee84e23, 0x1edfa5b4, 0x14e6030, 0x19e87be9, 0x92f533c, 0x1665d96c, 0x226653e, 0xa238d3e,
+ 0xf5c62c, 0x95bb7a, 0x1f0e5a41, 0x28789c3, 0x1f251d23, 0x8726609, 0xe918910, 0x8096848, 0xf63d028,
+ 0x152296a1, 0x9f561a8, 0x14d376fb, 0x898788a, 0x61a95fb, 0xa59466d, 0x159a003d, 0x1ad1698, 0x93cca08,
+ 0x1b314662, 0x706e006, 0x11ce1e30, 0x97b710, 0x172fbc0d, 0x8f50158, 0x11c7ffe7, 0xd182cce, 0xc6ad9e8,
+ 0x12ea31b2, 0xc4e4f38, 0x175b0d96, 0xec06337, 0x75a9c12, 0xb001fdf, 0x93e82f5, 0x34607de, 0xb8035ed,
+ 0x17f97924, 0x75cf9e6, 0xdceaedd, 0x2529924, 0x1a10c5ff, 0xb1a54dc, 0x19464d8, 0x2d1997, 0xde6a110,
+ 0x1e276ee5, 0x95c510c, 0x1aca7c7a, 0xfe48aca, 0x121ad4d9, 0xe4132c6, 0x8239b9d, 0x40ea9cd, 0x816c7b,
+ 0x632d7a4, 0xa679813, 0x5911fcf, 0x82b0f7c, 0x57b0ad5, 0xbef65, 0xd541365, 0x7f9921f, 0xc62e7a,
+ 0x3f4b32d, 0x58e50e1, 0x6427aed, 0xdcdda67, 0xe8c2d3e, 0x6aa54a4, 0x18df4c35, 0x49a6a8e, 0x3cd3d0c,
+ 0xd7adf2, 0xcbca97, 0x1bda5f2d, 0x3258579, 0x606b1e6, 0x6fc1b5b, 0x1ac27317, 0x503ca16, 0xa677435,
+ 0x57bc73, 0x3992a42, 0xbab987b, 0xfab25eb, 0x128912a4, 0x90a1dc4, 0x1402d591, 0x9ffbcfc, 0xaa48856,
+ 0x7a7c2dc, 0xcefd08a, 0x1b29bda6, 0xa785641, 0x16462d8c, 0x76241b7, 0x79b6c3b, 0x204ae18, 0xf41212b,
+ 0x1f567a4d, 0xd6ce6db, 0xedf1784, 0x111df34, 0x85d7955, 0x55fc189, 0x1b7ae265, 0xf9281ac, 0xded7740,
+ 0xf19468b, 0x83763bb, 0x8ff7234, 0x3da7df8, 0x9590ac3, 0xdc96f2a, 0x16e44896, 0x7931009, 0x99d5acc,
+ 0x10f7b842, 0xaef5e84, 0xc0310d7, 0xdebac2c, 0x2a7b137, 0x4342344, 0x19633649, 0x3a10624, 0x4b4cb56,
+ 0x1d809c59, 0xac007f, 0x1f0f4bcd, 0xa1ab06e, 0xc5042cf, 0x82c0c77, 0x76c7563, 0x22c30f3, 0x3bf1568,
+ 0x7a895be, 0xfcca554, 0x12e90e4c, 0x7b4ab5f, 0x13aeb76b, 0x5887e2c, 0x1d7fe1e3, 0x908c8e3, 0x95800ee,
+ 0xb36bd54, 0xf08905d, 0x4e73ae8, 0xf5a7e48, 0xa67cb0, 0x50e1067, 0x1b944a0a, 0xf29c83a, 0xb23cfb9,
+ 0xbe1db1, 0x54de6e8, 0xd4707f2, 0x8ebcc2d, 0x2c77056, 0x1568ce4, 0x15fcc849, 0x4069712, 0xe2ed85f,
+ 0x2c5ff09, 0x42a6929, 0x628e7ea, 0xbd5b355, 0xaf0bd79, 0xaa03699, 0xdb99816, 0x4379cef, 0x81d57b,
+ 0x11237f01, 0xe2a820b, 0xfd53b95, 0x6beb5ee, 0x1aeb790c, 0xe470d53, 0x2c2cfee, 0x1c1d8d8, 0xa520fc4,
+ 0x1518e034, 0xa584dd4, 0x29e572b, 0xd4594fc, 0x141a8f6f, 0x8dfccf3, 0x5d20ba3, 0x2eb60c3, 0x9f16eb0,
+ 0x11cec356, 0xf039f84, 0x1b0990c1, 0xc91e526, 0x10b65bae, 0xf0616e8, 0x173fa3ff, 0xec8ccf9, 0xbe32790,
+ 0x11da3e79, 0xe2f35c7, 0x908875c, 0xdacf7bd, 0x538c165, 0x8d1487f, 0x7c31aed, 0x21af228, 0x7e1689d,
+ 0xdfc23ca, 0x24f15dc, 0x25ef3c4, 0x35248cd, 0x99a0f43, 0xa4b6ecc, 0xd066b3, 0x2481152, 0x37a7688,
+ 0x15a444b6, 0xb62300c, 0x4b841b, 0xa655e79, 0xd53226d, 0xbeb348a, 0x127f3c2, 0xb989247, 0x71a277d,
+ 0x19e9dfcb, 0xb8f92d0, 0xe2d226c, 0x390a8b0, 0x183cc462, 0x7bd8167, 0x1f32a552, 0x5e02db4, 0xa146ee9,
+ 0x1a003957, 0x1c95f61, 0x1eeec155, 0x26f811f, 0xf9596ba, 0x3082bfb, 0x96df083, 0x3e3a289, 0x7e2d8be,
+ 0x157a63e0, 0x99b8941, 0x1da7d345, 0xcc6cd0, 0x10beed9a, 0x48e83c0, 0x13aa2e25, 0x7cad710, 0x4029988,
+ 0x13dfa9dd, 0xb94f884, 0x1f4adfef, 0xb88543, 0x16f5f8dc, 0xa6a67f4, 0x14e274e2, 0x5e56cf4, 0x2f24ef,
+ 0x1e9ef967, 0xfe09bad, 0xfe079b3, 0xcc0ae9e, 0xb3edf6d, 0x3e961bc, 0x130d7831, 0x31043d6, 0xba986f9,
+ 0x1d28055, 0x65240ca, 0x4971fa3, 0x81b17f8, 0x11ec34a5, 0x8366ddc, 0x1471809, 0xfa5f1c6, 0xc911e15,
+ 0x8849491, 0xcf4c2e2, 0x14471b91, 0x39f75be, 0x445c21e, 0xf1585e9, 0x72cc11f, 0x4c79f0c, 0xe5522e1,
+ 0x1874c1ee, 0x4444211, 0x7914884, 0x3d1b133, 0x25ba3c, 0x4194f65, 0x1c0457ef, 0xac4899d, 0xe1fa66c,
+ 0x130a7918, 0x9b8d312, 0x4b1c5c8, 0x61ccac3, 0x18c8aa6f, 0xe93cb0a, 0xdccb12c, 0xde10825, 0x969737d,
+ 0xf58c0c3, 0x7cee6a9, 0xc2c329a, 0xc7f9ed9, 0x107b3981, 0x696a40e, 0x152847ff, 0x4d88754, 0xb141f47,
+ 0x5a16ffe, 0x3a7870a, 0x18667659, 0x3b72b03, 0xb1c9435, 0x9285394, 0xa00005a, 0x37506c, 0x2edc0bb,
+ 0x19afe392, 0xeb39cac, 0x177ef286, 0xdf87197, 0x19f844ed, 0x31fe8, 0x15f9bfd, 0x80dbec, 0x342e96e,
+ 0x497aced, 0xe88e909, 0x1f5fa9ba, 0x530a6ee, 0x1ef4e3f1, 0x69ffd12, 0x583006d, 0x2ecc9b1, 0x362db70,
+ 0x18c7bdc5, 0xf4bb3c5, 0x1c90b957, 0xf067c09, 0x9768f2b, 0xf73566a, 0x1939a900, 0x198c38a, 0x202a2a1,
+ 0x4bbf5a6, 0x4e265bc, 0x1f44b6e7, 0x185ca49, 0xa39e81b, 0x24aff5b, 0x4acc9c2, 0x638bdd3, 0xb65b2a8,
+ 0x6def8be, 0xb94537a, 0x10b81dee, 0xe00ec55, 0x2f2cdf7, 0xc20622d, 0x2d20f36, 0xe03c8c9, 0x898ea76,
+ 0x8e3921b, 0x8905bff, 0x1e94b6c8, 0xee7ad86, 0x154797f2, 0xa620863, 0x3fbd0d9, 0x1f3caab, 0x30c24bd,
+ 0x19d3892f, 0x59c17a2, 0x1ab4b0ae, 0xf8714ee, 0x90c4098, 0xa9c800d, 0x1910236b, 0xea808d3, 0x9ae2f31,
+ 0x1a15ad64, 0xa48c8d1, 0x184635a4, 0xb725ef1, 0x11921dcc, 0x3f866df, 0x16c27568, 0xbdf580a, 0xb08f55c,
+ 0x186ee1c, 0xb1627fa, 0x34e82f6, 0x933837e, 0xf311be5, 0xfedb03b, 0x167f72cd, 0xa5469c0, 0x9c82531,
+ 0xb92a24b, 0x14fdc8b, 0x141980d1, 0xbdc3a49, 0x7e02bb1, 0xaf4e6dd, 0x106d99e1, 0xd4616fc, 0x93c2717,
+ 0x1c0a0507, 0xc6d5fed, 0x9a03d8b, 0xa1d22b0, 0x127853e3, 0xc4ac6b8, 0x1a048cf7, 0x9afb72c, 0x65d485d,
+ 0x72d5998, 0xe9fa744, 0xe49e82c, 0x253cf80, 0x5f777ce, 0xa3799a5, 0x17270cbb, 0xc1d1ef0, 0xdf74977,
+ 0x114cb859, 0xfa8e037, 0xb8f3fe5, 0xc734cc6, 0x70d3d61, 0xeadac62, 0x12093dd0, 0x9add67d, 0x87200d6,
+ 0x175bcbb, 0xb29b49f, 0x1806b79c, 0x12fb61f, 0x170b3a10, 0x3aaf1cf, 0xa224085, 0x79d26af, 0x97759e2,
+ 0x92e19f1, 0xb32714d, 0x1f00d9f1, 0xc728619, 0x9e6f627, 0xe745e24, 0x18ea4ace, 0xfc60a41, 0x125f5b2,
+ 0xc3cf512, 0x39ed486, 0xf4d15fa, 0xf9167fd, 0x1c1f5dd5, 0xc21a53e, 0x1897930, 0x957a112, 0x21059a0,
+ 0x1f9e3ddc, 0xa4dfced, 0x8427f6f, 0x726fbe7, 0x1ea658f8, 0x2fdcd4c, 0x17e9b66f, 0xb2e7c2e, 0x39923bf,
+ 0x1bae104, 0x3973ce5, 0xc6f264c, 0x3511b84, 0x124195d7, 0x11996bd, 0x20be23d, 0xdc437c4, 0x4b4f16b,
+ 0x11902a0, 0x6c29cc9, 0x1d5ffbe6, 0xdb0b4c7, 0x10144c14, 0x2f2b719, 0x301189, 0x2343336, 0xa0bf2ac,
+}
+
+func sm2P256GetScalar(b *[32]byte, a []byte) {
+ var scalarBytes []byte
+
+ n := new(big.Int).SetBytes(a)
+ if n.Cmp(sm2P256.N) >= 0 {
+ n.Mod(n, sm2P256.N)
+ scalarBytes = n.Bytes()
+ } else {
+ scalarBytes = a
+ }
+ for i, v := range scalarBytes {
+ b[len(scalarBytes)-(1+i)] = v
+ }
+}
+
+func sm2P256PointAddMixed(xOut, yOut, zOut, x1, y1, z1, x2, y2 *sm2P256FieldElement) {
+ var z1z1, z1z1z1, s2, u2, h, i, j, r, rr, v, tmp sm2P256FieldElement
+
+ sm2P256Square(&z1z1, z1)
+ sm2P256Add(&tmp, z1, z1)
+
+ sm2P256Mul(&u2, x2, &z1z1)
+ sm2P256Mul(&z1z1z1, z1, &z1z1)
+ sm2P256Mul(&s2, y2, &z1z1z1)
+ sm2P256Sub(&h, &u2, x1)
+ sm2P256Add(&i, &h, &h)
+ sm2P256Square(&i, &i)
+ sm2P256Mul(&j, &h, &i)
+ sm2P256Sub(&r, &s2, y1)
+ sm2P256Add(&r, &r, &r)
+ sm2P256Mul(&v, x1, &i)
+
+ sm2P256Mul(zOut, &tmp, &h)
+ sm2P256Square(&rr, &r)
+ sm2P256Sub(xOut, &rr, &j)
+ sm2P256Sub(xOut, xOut, &v)
+ sm2P256Sub(xOut, xOut, &v)
+
+ sm2P256Sub(&tmp, &v, xOut)
+ sm2P256Mul(yOut, &tmp, &r)
+ sm2P256Mul(&tmp, y1, &j)
+ sm2P256Sub(yOut, yOut, &tmp)
+ sm2P256Sub(yOut, yOut, &tmp)
+}
+
+// sm2P256CopyConditional sets out=in if mask = 0xffffffff in constant time.
+//
+// On entry: mask is either 0 or 0xffffffff.
+func sm2P256CopyConditional(out, in *sm2P256FieldElement, mask uint32) {
+ for i := 0; i < 9; i++ {
+ tmp := mask & (in[i] ^ out[i])
+ out[i] ^= tmp
+ }
+}
+
+// sm2P256SelectAffinePoint sets {out_x,out_y} to the index'th entry of table.
+// On entry: index < 16, table[0] must be zero.
+func sm2P256SelectAffinePoint(xOut, yOut *sm2P256FieldElement, table []uint32, index uint32) {
+ for i := range xOut {
+ xOut[i] = 0
+ }
+ for i := range yOut {
+ yOut[i] = 0
+ }
+
+ for i := uint32(1); i < 16; i++ {
+ mask := i ^ index
+ mask |= mask >> 2
+ mask |= mask >> 1
+ mask &= 1
+ mask--
+ for j := range xOut {
+ xOut[j] |= table[0] & mask
+ table = table[1:]
+ }
+ for j := range yOut {
+ yOut[j] |= table[0] & mask
+ table = table[1:]
+ }
+ }
+}
+
+// sm2P256SelectJacobianPoint sets {out_x,out_y,out_z} to the index'th entry of
+// table.
+// On entry: index < 16, table[0] must be zero.
+func sm2P256SelectJacobianPoint(xOut, yOut, zOut *sm2P256FieldElement, table *[16][3]sm2P256FieldElement, index uint32) {
+ for i := range xOut {
+ xOut[i] = 0
+ }
+ for i := range yOut {
+ yOut[i] = 0
+ }
+ for i := range zOut {
+ zOut[i] = 0
+ }
+
+ // The implicit value at index 0 is all zero. We don't need to perform that
+ // iteration of the loop because we already set out_* to zero.
+ for i := uint32(1); i < 16; i++ {
+ mask := i ^ index
+ mask |= mask >> 2
+ mask |= mask >> 1
+ mask &= 1
+ mask--
+ for j := range xOut {
+ xOut[j] |= table[i][0][j] & mask
+ }
+ for j := range yOut {
+ yOut[j] |= table[i][1][j] & mask
+ }
+ for j := range zOut {
+ zOut[j] |= table[i][2][j] & mask
+ }
+ }
+}
+
+// sm2P256GetBit returns the bit'th bit of scalar.
+func sm2P256GetBit(scalar *[32]uint8, bit uint) uint32 {
+ return uint32(((scalar[bit>>3]) >> (bit & 7)) & 1)
+}
+
+// sm2P256ScalarBaseMult sets {xOut,yOut,zOut} = scalar*G where scalar is a
+// little-endian number. Note that the value of scalar must be less than the
+// order of the group.
+func sm2P256ScalarBaseMult(xOut, yOut, zOut *sm2P256FieldElement, scalar *[32]uint8) {
+ nIsInfinityMask := ^uint32(0)
+ var px, py, tx, ty, tz sm2P256FieldElement
+ var pIsNoninfiniteMask, mask, tableOffset uint32
+
+ for i := range xOut {
+ xOut[i] = 0
+ }
+ for i := range yOut {
+ yOut[i] = 0
+ }
+ for i := range zOut {
+ zOut[i] = 0
+ }
+
+ // The loop adds bits at positions 0, 64, 128 and 192, followed by
+ // positions 32,96,160 and 224 and does this 32 times.
+ for i := uint(0); i < 32; i++ {
+ if i != 0 {
+ sm2P256PointDouble(xOut, yOut, zOut, xOut, yOut, zOut)
+ }
+ tableOffset = 0
+ for j := uint(0); j <= 32; j += 32 {
+ bit0 := sm2P256GetBit(scalar, 31-i+j)
+ bit1 := sm2P256GetBit(scalar, 95-i+j)
+ bit2 := sm2P256GetBit(scalar, 159-i+j)
+ bit3 := sm2P256GetBit(scalar, 223-i+j)
+ index := bit0 | (bit1 << 1) | (bit2 << 2) | (bit3 << 3)
+
+ sm2P256SelectAffinePoint(&px, &py, sm2P256Precomputed[tableOffset:], index)
+ tableOffset += 30 * 9
+
+ // Since scalar is less than the order of the group, we know that
+ // {xOut,yOut,zOut} != {px,py,1}, unless both are zero, which we handle
+ // below.
+ sm2P256PointAddMixed(&tx, &ty, &tz, xOut, yOut, zOut, &px, &py)
+ // The result of pointAddMixed is incorrect if {xOut,yOut,zOut} is zero
+ // (a.k.a. the point at infinity). We handle that situation by
+ // copying the point from the table.
+ sm2P256CopyConditional(xOut, &px, nIsInfinityMask)
+ sm2P256CopyConditional(yOut, &py, nIsInfinityMask)
+ sm2P256CopyConditional(zOut, &sm2P256Factor[1], nIsInfinityMask)
+
+ // Equally, the result is also wrong if the point from the table is
+ // zero, which happens when the index is zero. We handle that by
+ // only copying from {tx,ty,tz} to {xOut,yOut,zOut} if index != 0.
+ pIsNoninfiniteMask = nonZeroToAllOnes(index)
+ mask = pIsNoninfiniteMask & ^nIsInfinityMask
+ sm2P256CopyConditional(xOut, &tx, mask)
+ sm2P256CopyConditional(yOut, &ty, mask)
+ sm2P256CopyConditional(zOut, &tz, mask)
+ // If p was not zero, then n is now non-zero.
+ nIsInfinityMask &^= pIsNoninfiniteMask
+ }
+ }
+}
+
+func sm2P256ScalarMult(xOut, yOut, zOut, x, y *sm2P256FieldElement, scalar *[32]uint8) {
+ var precomp [16][3]sm2P256FieldElement
+ var px, py, pz, tx, ty, tz sm2P256FieldElement
+ var nIsInfinityMask, index, pIsNoninfiniteMask, mask uint32
+
+ // We precompute 0,1,2,... times {x,y}.
+ precomp[1][0] = *x
+ precomp[1][1] = *y
+ precomp[1][2] = sm2P256Factor[1]
+
+ for i := 2; i < 16; i += 2 {
+ sm2P256PointDouble(&precomp[i][0], &precomp[i][1], &precomp[i][2], &precomp[i/2][0], &precomp[i/2][1], &precomp[i/2][2])
+ sm2P256PointAddMixed(&precomp[i+1][0], &precomp[i+1][1], &precomp[i+1][2], &precomp[i][0], &precomp[i][1], &precomp[i][2], x, y)
+ }
+
+ for i := range xOut {
+ xOut[i] = 0
+ }
+ for i := range yOut {
+ yOut[i] = 0
+ }
+ for i := range zOut {
+ zOut[i] = 0
+ }
+ nIsInfinityMask = ^uint32(0)
+
+ // We add in a window of four bits each iteration and do this 64 times.
+ for i := 0; i < 64; i++ {
+ if i != 0 {
+ sm2P256PointDouble(xOut, yOut, zOut, xOut, yOut, zOut)
+ sm2P256PointDouble(xOut, yOut, zOut, xOut, yOut, zOut)
+ sm2P256PointDouble(xOut, yOut, zOut, xOut, yOut, zOut)
+ sm2P256PointDouble(xOut, yOut, zOut, xOut, yOut, zOut)
+ }
+
+ index = uint32(scalar[31-i/2])
+ if (i & 1) == 1 {
+ index &= 15
+ } else {
+ index >>= 4
+ }
+
+ // See the comments in scalarBaseMult about handling infinities.
+ sm2P256SelectJacobianPoint(&px, &py, &pz, &precomp, index)
+ sm2P256PointAdd(xOut, yOut, zOut, &px, &py, &pz, &tx, &ty, &tz)
+ sm2P256CopyConditional(xOut, &px, nIsInfinityMask)
+ sm2P256CopyConditional(yOut, &py, nIsInfinityMask)
+ sm2P256CopyConditional(zOut, &pz, nIsInfinityMask)
+
+ pIsNoninfiniteMask = nonZeroToAllOnes(index)
+ mask = pIsNoninfiniteMask & ^nIsInfinityMask
+ sm2P256CopyConditional(xOut, &tx, mask)
+ sm2P256CopyConditional(yOut, &ty, mask)
+ sm2P256CopyConditional(zOut, &tz, mask)
+ nIsInfinityMask &^= pIsNoninfiniteMask
+ }
+}
+
+func sm2P256PointToAffine(xOut, yOut, x, y, z *sm2P256FieldElement) {
+ var zInv, zInvSq sm2P256FieldElement
+
+ zz := sm2P256ToBig(z)
+ zz.ModInverse(zz, sm2P256.P)
+ sm2P256FromBig(&zInv, zz)
+
+ sm2P256Square(&zInvSq, &zInv)
+ sm2P256Mul(xOut, x, &zInvSq)
+ sm2P256Mul(&zInv, &zInv, &zInvSq)
+ sm2P256Mul(yOut, y, &zInv)
+}
+
+func sm2P256ToAffine(x, y, z *sm2P256FieldElement) (xOut, yOut *big.Int) {
+ var xx, yy sm2P256FieldElement
+
+ sm2P256PointToAffine(&xx, &yy, x, y, z)
+ return sm2P256ToBig(&xx), sm2P256ToBig(&yy)
+}
+
+var sm2P256Factor = []sm2P256FieldElement{
+ sm2P256FieldElement{0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0},
+ sm2P256FieldElement{0x2, 0x0, 0x1FFFFF00, 0x7FF, 0x0, 0x0, 0x0, 0x2000000, 0x0},
+ sm2P256FieldElement{0x4, 0x0, 0x1FFFFE00, 0xFFF, 0x0, 0x0, 0x0, 0x4000000, 0x0},
+ sm2P256FieldElement{0x6, 0x0, 0x1FFFFD00, 0x17FF, 0x0, 0x0, 0x0, 0x6000000, 0x0},
+ sm2P256FieldElement{0x8, 0x0, 0x1FFFFC00, 0x1FFF, 0x0, 0x0, 0x0, 0x8000000, 0x0},
+ sm2P256FieldElement{0xA, 0x0, 0x1FFFFB00, 0x27FF, 0x0, 0x0, 0x0, 0xA000000, 0x0},
+ sm2P256FieldElement{0xC, 0x0, 0x1FFFFA00, 0x2FFF, 0x0, 0x0, 0x0, 0xC000000, 0x0},
+ sm2P256FieldElement{0xE, 0x0, 0x1FFFF900, 0x37FF, 0x0, 0x0, 0x0, 0xE000000, 0x0},
+ sm2P256FieldElement{0x10, 0x0, 0x1FFFF800, 0x3FFF, 0x0, 0x0, 0x0, 0x0, 0x01},
+}
+
+func sm2P256Scalar(b *sm2P256FieldElement, a int) {
+ sm2P256Mul(b, b, &sm2P256Factor[a])
+}
+
+// (x3, y3, z3) = (x1, y1, z1) + (x2, y2, z2)
+func sm2P256PointAdd(x1, y1, z1, x2, y2, z2, x3, y3, z3 *sm2P256FieldElement) {
+ var u1, u2, z22, z12, z23, z13, s1, s2, h, h2, r, r2, tm sm2P256FieldElement
+
+ if sm2P256ToBig(z1).Sign() == 0 {
+ sm2P256Dup(x3, x2)
+ sm2P256Dup(y3, y2)
+ sm2P256Dup(z3, z2)
+ return
+ }
+
+ if sm2P256ToBig(z2).Sign() == 0 {
+ sm2P256Dup(x3, x1)
+ sm2P256Dup(y3, y1)
+ sm2P256Dup(z3, z1)
+ return
+ }
+
+ sm2P256Square(&z12, z1) // z12 = z1 ^ 2
+ sm2P256Square(&z22, z2) // z22 = z2 ^ 2
+
+ sm2P256Mul(&z13, &z12, z1) // z13 = z1 ^ 3
+ sm2P256Mul(&z23, &z22, z2) // z23 = z2 ^ 3
+
+ sm2P256Mul(&u1, x1, &z22) // u1 = x1 * z2 ^ 2
+ sm2P256Mul(&u2, x2, &z12) // u2 = x2 * z1 ^ 2
+
+ sm2P256Mul(&s1, y1, &z23) // s1 = y1 * z2 ^ 3
+ sm2P256Mul(&s2, y2, &z13) // s2 = y2 * z1 ^ 3
+
+ if sm2P256ToBig(&u1).Cmp(sm2P256ToBig(&u2)) == 0 &&
+ sm2P256ToBig(&s1).Cmp(sm2P256ToBig(&s2)) == 0 {
+ sm2P256PointDouble(x1, y1, z1, x1, y1, z1)
+ }
+
+ sm2P256Sub(&h, &u2, &u1) // h = u2 - u1
+ sm2P256Sub(&r, &s2, &s1) // r = s2 - s1
+
+ sm2P256Square(&r2, &r) // r2 = r ^ 2
+ sm2P256Square(&h2, &h) // h2 = h ^ 2
+
+ sm2P256Mul(&tm, &h2, &h) // tm = h ^ 3
+ sm2P256Sub(x3, &r2, &tm)
+ sm2P256Mul(&tm, &u1, &h2)
+ sm2P256Scalar(&tm, 2) // tm = 2 * (u1 * h ^ 2)
+ sm2P256Sub(x3, x3, &tm) // x3 = r ^ 2 - h ^ 3 - 2 * u1 * h ^ 2
+
+ sm2P256Mul(&tm, &u1, &h2) // tm = u1 * h ^ 2
+ sm2P256Sub(&tm, &tm, x3) // tm = u1 * h ^ 2 - x3
+ sm2P256Mul(y3, &r, &tm)
+ sm2P256Mul(&tm, &h2, &h) // tm = h ^ 3
+ sm2P256Mul(&tm, &tm, &s1) // tm = s1 * h ^ 3
+ sm2P256Sub(y3, y3, &tm) // y3 = r * (u1 * h ^ 2 - x3) - s1 * h ^ 3
+
+ sm2P256Mul(z3, z1, z2)
+ sm2P256Mul(z3, z3, &h) // z3 = z1 * z3 * h
+}
+
+func sm2P256PointDouble(x3, y3, z3, x, y, z *sm2P256FieldElement) {
+ var s, m, m2, x2, y2, z2, z4, y4, az4 sm2P256FieldElement
+
+ sm2P256Square(&x2, x) // x2 = x ^ 2
+ sm2P256Square(&y2, y) // y2 = y ^ 2
+ sm2P256Square(&z2, z) // z2 = z ^ 2
+
+ sm2P256Square(&z4, z) // z4 = z ^ 2
+ sm2P256Mul(&z4, &z4, z) // z4 = z ^ 3
+ sm2P256Mul(&z4, &z4, z) // z4 = z ^ 4
+
+ sm2P256Square(&y4, y) // y4 = y ^ 2
+ sm2P256Mul(&y4, &y4, y) // y4 = y ^ 3
+ sm2P256Mul(&y4, &y4, y) // y4 = y ^ 4
+ sm2P256Scalar(&y4, 8) // y4 = 8 * y ^ 4
+
+ sm2P256Mul(&s, x, &y2)
+ sm2P256Scalar(&s, 4) // s = 4 * x * y ^ 2
+
+ sm2P256Dup(&m, &x2)
+ sm2P256Scalar(&m, 3)
+ sm2P256Mul(&az4, &sm2P256.a, &z4)
+ sm2P256Add(&m, &m, &az4) // m = 3 * x ^ 2 + a * z ^ 4
+
+ sm2P256Square(&m2, &m) // m2 = m ^ 2
+
+ sm2P256Add(z3, y, z)
+ sm2P256Square(z3, z3)
+ sm2P256Sub(z3, z3, &z2)
+ sm2P256Sub(z3, z3, &y2) // z' = (y + z) ^2 - z ^ 2 - y ^ 2
+
+ sm2P256Sub(x3, &m2, &s)
+ sm2P256Sub(x3, x3, &s) // x' = m2 - 2 * s
+
+ sm2P256Sub(y3, &s, x3)
+ sm2P256Mul(y3, y3, &m)
+ sm2P256Sub(y3, y3, &y4) // y' = m * (s - x') - 8 * y ^ 4
+}
+
+// p256Zero31 is 0 mod p.
+var sm2P256Zero31 = sm2P256FieldElement{0x7FFFFFF8, 0x3FFFFFFC, 0x800003FC, 0x3FFFDFFC, 0x7FFFFFFC, 0x3FFFFFFC, 0x7FFFFFFC, 0x37FFFFFC, 0x7FFFFFFC}
+
+// c = a + b
+func sm2P256Add(c, a, b *sm2P256FieldElement) {
+ carry := uint32(0)
+ for i := 0; ; i++ {
+ c[i] = a[i] + b[i]
+ c[i] += carry
+ carry = c[i] >> 29
+ c[i] &= bottom29Bits
+ i++
+ if i == 9 {
+ break
+ }
+ c[i] = a[i] + b[i]
+ c[i] += carry
+ carry = c[i] >> 28
+ c[i] &= bottom28Bits
+ }
+ sm2P256ReduceCarry(c, carry)
+}
+
+// c = a - b
+func sm2P256Sub(c, a, b *sm2P256FieldElement) {
+ var carry uint32
+
+ for i := 0; ; i++ {
+ c[i] = a[i] - b[i]
+ c[i] += sm2P256Zero31[i]
+ c[i] += carry
+ carry = c[i] >> 29
+ c[i] &= bottom29Bits
+ i++
+ if i == 9 {
+ break
+ }
+ c[i] = a[i] - b[i]
+ c[i] += sm2P256Zero31[i]
+ c[i] += carry
+ carry = c[i] >> 28
+ c[i] &= bottom28Bits
+ }
+ sm2P256ReduceCarry(c, carry)
+}
+
+// c = a * b
+func sm2P256Mul(c, a, b *sm2P256FieldElement) {
+ var tmp sm2P256LargeFieldElement
+
+ tmp[0] = uint64(a[0]) * uint64(b[0])
+ tmp[1] = uint64(a[0])*(uint64(b[1])<<0) +
+ uint64(a[1])*(uint64(b[0])<<0)
+ tmp[2] = uint64(a[0])*(uint64(b[2])<<0) +
+ uint64(a[1])*(uint64(b[1])<<1) +
+ uint64(a[2])*(uint64(b[0])<<0)
+ tmp[3] = uint64(a[0])*(uint64(b[3])<<0) +
+ uint64(a[1])*(uint64(b[2])<<0) +
+ uint64(a[2])*(uint64(b[1])<<0) +
+ uint64(a[3])*(uint64(b[0])<<0)
+ tmp[4] = uint64(a[0])*(uint64(b[4])<<0) +
+ uint64(a[1])*(uint64(b[3])<<1) +
+ uint64(a[2])*(uint64(b[2])<<0) +
+ uint64(a[3])*(uint64(b[1])<<1) +
+ uint64(a[4])*(uint64(b[0])<<0)
+ tmp[5] = uint64(a[0])*(uint64(b[5])<<0) +
+ uint64(a[1])*(uint64(b[4])<<0) +
+ uint64(a[2])*(uint64(b[3])<<0) +
+ uint64(a[3])*(uint64(b[2])<<0) +
+ uint64(a[4])*(uint64(b[1])<<0) +
+ uint64(a[5])*(uint64(b[0])<<0)
+ tmp[6] = uint64(a[0])*(uint64(b[6])<<0) +
+ uint64(a[1])*(uint64(b[5])<<1) +
+ uint64(a[2])*(uint64(b[4])<<0) +
+ uint64(a[3])*(uint64(b[3])<<1) +
+ uint64(a[4])*(uint64(b[2])<<0) +
+ uint64(a[5])*(uint64(b[1])<<1) +
+ uint64(a[6])*(uint64(b[0])<<0)
+ tmp[7] = uint64(a[0])*(uint64(b[7])<<0) +
+ uint64(a[1])*(uint64(b[6])<<0) +
+ uint64(a[2])*(uint64(b[5])<<0) +
+ uint64(a[3])*(uint64(b[4])<<0) +
+ uint64(a[4])*(uint64(b[3])<<0) +
+ uint64(a[5])*(uint64(b[2])<<0) +
+ uint64(a[6])*(uint64(b[1])<<0) +
+ uint64(a[7])*(uint64(b[0])<<0)
+ // tmp[8] has the greatest value but doesn't overflow. See logic in
+ // p256Square.
+ tmp[8] = uint64(a[0])*(uint64(b[8])<<0) +
+ uint64(a[1])*(uint64(b[7])<<1) +
+ uint64(a[2])*(uint64(b[6])<<0) +
+ uint64(a[3])*(uint64(b[5])<<1) +
+ uint64(a[4])*(uint64(b[4])<<0) +
+ uint64(a[5])*(uint64(b[3])<<1) +
+ uint64(a[6])*(uint64(b[2])<<0) +
+ uint64(a[7])*(uint64(b[1])<<1) +
+ uint64(a[8])*(uint64(b[0])<<0)
+ tmp[9] = uint64(a[1])*(uint64(b[8])<<0) +
+ uint64(a[2])*(uint64(b[7])<<0) +
+ uint64(a[3])*(uint64(b[6])<<0) +
+ uint64(a[4])*(uint64(b[5])<<0) +
+ uint64(a[5])*(uint64(b[4])<<0) +
+ uint64(a[6])*(uint64(b[3])<<0) +
+ uint64(a[7])*(uint64(b[2])<<0) +
+ uint64(a[8])*(uint64(b[1])<<0)
+ tmp[10] = uint64(a[2])*(uint64(b[8])<<0) +
+ uint64(a[3])*(uint64(b[7])<<1) +
+ uint64(a[4])*(uint64(b[6])<<0) +
+ uint64(a[5])*(uint64(b[5])<<1) +
+ uint64(a[6])*(uint64(b[4])<<0) +
+ uint64(a[7])*(uint64(b[3])<<1) +
+ uint64(a[8])*(uint64(b[2])<<0)
+ tmp[11] = uint64(a[3])*(uint64(b[8])<<0) +
+ uint64(a[4])*(uint64(b[7])<<0) +
+ uint64(a[5])*(uint64(b[6])<<0) +
+ uint64(a[6])*(uint64(b[5])<<0) +
+ uint64(a[7])*(uint64(b[4])<<0) +
+ uint64(a[8])*(uint64(b[3])<<0)
+ tmp[12] = uint64(a[4])*(uint64(b[8])<<0) +
+ uint64(a[5])*(uint64(b[7])<<1) +
+ uint64(a[6])*(uint64(b[6])<<0) +
+ uint64(a[7])*(uint64(b[5])<<1) +
+ uint64(a[8])*(uint64(b[4])<<0)
+ tmp[13] = uint64(a[5])*(uint64(b[8])<<0) +
+ uint64(a[6])*(uint64(b[7])<<0) +
+ uint64(a[7])*(uint64(b[6])<<0) +
+ uint64(a[8])*(uint64(b[5])<<0)
+ tmp[14] = uint64(a[6])*(uint64(b[8])<<0) +
+ uint64(a[7])*(uint64(b[7])<<1) +
+ uint64(a[8])*(uint64(b[6])<<0)
+ tmp[15] = uint64(a[7])*(uint64(b[8])<<0) +
+ uint64(a[8])*(uint64(b[7])<<0)
+ tmp[16] = uint64(a[8]) * (uint64(b[8]) << 0)
+ sm2P256ReduceDegree(c, &tmp)
+}
+
+// b = a * a
+func sm2P256Square(b, a *sm2P256FieldElement) {
+ var tmp sm2P256LargeFieldElement
+
+ tmp[0] = uint64(a[0]) * uint64(a[0])
+ tmp[1] = uint64(a[0]) * (uint64(a[1]) << 1)
+ tmp[2] = uint64(a[0])*(uint64(a[2])<<1) +
+ uint64(a[1])*(uint64(a[1])<<1)
+ tmp[3] = uint64(a[0])*(uint64(a[3])<<1) +
+ uint64(a[1])*(uint64(a[2])<<1)
+ tmp[4] = uint64(a[0])*(uint64(a[4])<<1) +
+ uint64(a[1])*(uint64(a[3])<<2) +
+ uint64(a[2])*uint64(a[2])
+ tmp[5] = uint64(a[0])*(uint64(a[5])<<1) +
+ uint64(a[1])*(uint64(a[4])<<1) +
+ uint64(a[2])*(uint64(a[3])<<1)
+ tmp[6] = uint64(a[0])*(uint64(a[6])<<1) +
+ uint64(a[1])*(uint64(a[5])<<2) +
+ uint64(a[2])*(uint64(a[4])<<1) +
+ uint64(a[3])*(uint64(a[3])<<1)
+ tmp[7] = uint64(a[0])*(uint64(a[7])<<1) +
+ uint64(a[1])*(uint64(a[6])<<1) +
+ uint64(a[2])*(uint64(a[5])<<1) +
+ uint64(a[3])*(uint64(a[4])<<1)
+ // tmp[8] has the greatest value of 2**61 + 2**60 + 2**61 + 2**60 + 2**60,
+ // which is < 2**64 as required.
+ tmp[8] = uint64(a[0])*(uint64(a[8])<<1) +
+ uint64(a[1])*(uint64(a[7])<<2) +
+ uint64(a[2])*(uint64(a[6])<<1) +
+ uint64(a[3])*(uint64(a[5])<<2) +
+ uint64(a[4])*uint64(a[4])
+ tmp[9] = uint64(a[1])*(uint64(a[8])<<1) +
+ uint64(a[2])*(uint64(a[7])<<1) +
+ uint64(a[3])*(uint64(a[6])<<1) +
+ uint64(a[4])*(uint64(a[5])<<1)
+ tmp[10] = uint64(a[2])*(uint64(a[8])<<1) +
+ uint64(a[3])*(uint64(a[7])<<2) +
+ uint64(a[4])*(uint64(a[6])<<1) +
+ uint64(a[5])*(uint64(a[5])<<1)
+ tmp[11] = uint64(a[3])*(uint64(a[8])<<1) +
+ uint64(a[4])*(uint64(a[7])<<1) +
+ uint64(a[5])*(uint64(a[6])<<1)
+ tmp[12] = uint64(a[4])*(uint64(a[8])<<1) +
+ uint64(a[5])*(uint64(a[7])<<2) +
+ uint64(a[6])*uint64(a[6])
+ tmp[13] = uint64(a[5])*(uint64(a[8])<<1) +
+ uint64(a[6])*(uint64(a[7])<<1)
+ tmp[14] = uint64(a[6])*(uint64(a[8])<<1) +
+ uint64(a[7])*(uint64(a[7])<<1)
+ tmp[15] = uint64(a[7]) * (uint64(a[8]) << 1)
+ tmp[16] = uint64(a[8]) * uint64(a[8])
+ sm2P256ReduceDegree(b, &tmp)
+}
+
+// nonZeroToAllOnes returns:
+// 0xffffffff for 0 < x <= 2**31
+// 0 for x == 0 or x > 2**31.
+func nonZeroToAllOnes(x uint32) uint32 {
+ return ((x - 1) >> 31) - 1
+}
+
+var sm2P256Carry = [8 * 9]uint32{
+ 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+ 0x2, 0x0, 0x1FFFFF00, 0x7FF, 0x0, 0x0, 0x0, 0x2000000, 0x0,
+ 0x4, 0x0, 0x1FFFFE00, 0xFFF, 0x0, 0x0, 0x0, 0x4000000, 0x0,
+ 0x6, 0x0, 0x1FFFFD00, 0x17FF, 0x0, 0x0, 0x0, 0x6000000, 0x0,
+ 0x8, 0x0, 0x1FFFFC00, 0x1FFF, 0x0, 0x0, 0x0, 0x8000000, 0x0,
+ 0xA, 0x0, 0x1FFFFB00, 0x27FF, 0x0, 0x0, 0x0, 0xA000000, 0x0,
+ 0xC, 0x0, 0x1FFFFA00, 0x2FFF, 0x0, 0x0, 0x0, 0xC000000, 0x0,
+ 0xE, 0x0, 0x1FFFF900, 0x37FF, 0x0, 0x0, 0x0, 0xE000000, 0x0,
+}
+
+// carry < 2 ^ 3
+func sm2P256ReduceCarry(a *sm2P256FieldElement, carry uint32) {
+ a[0] += sm2P256Carry[carry*9+0]
+ a[2] += sm2P256Carry[carry*9+2]
+ a[3] += sm2P256Carry[carry*9+3]
+ a[7] += sm2P256Carry[carry*9+7]
+}
+
+// 这代码真是丑比了，我也是对自己醉了。。。
+// 你最好别改这个代码，不然你会死的很惨。。
+func sm2P256ReduceDegree(a *sm2P256FieldElement, b *sm2P256LargeFieldElement) {
+ var tmp [18]uint32
+ var carry, x, xMask uint32
+
+ // tmp
+ // 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 ...
+ // 29 | 28 | 29 | 28 | 29 | 28 | 29 | 28 | 29 | 28 | 29 ...
+ tmp[0] = uint32(b[0]) & bottom29Bits
+ tmp[1] = uint32(b[0]) >> 29
+ tmp[1] |= (uint32(b[0]>>32) << 3) & bottom28Bits
+ tmp[1] += uint32(b[1]) & bottom28Bits
+ carry = tmp[1] >> 28
+ tmp[1] &= bottom28Bits
+ for i := 2; i < 17; i++ {
+ tmp[i] = (uint32(b[i-2] >> 32)) >> 25
+ tmp[i] += (uint32(b[i-1])) >> 28
+ tmp[i] += (uint32(b[i-1]>>32) << 4) & bottom29Bits
+ tmp[i] += uint32(b[i]) & bottom29Bits
+ tmp[i] += carry
+ carry = tmp[i] >> 29
+ tmp[i] &= bottom29Bits
+
+ i++
+ if i == 17 {
+ break
+ }
+ tmp[i] = uint32(b[i-2]>>32) >> 25
+ tmp[i] += uint32(b[i-1]) >> 29
+ tmp[i] += ((uint32(b[i-1] >> 32)) << 3) & bottom28Bits
+ tmp[i] += uint32(b[i]) & bottom28Bits
+ tmp[i] += carry
+ carry = tmp[i] >> 28
+ tmp[i] &= bottom28Bits
+ }
+ tmp[17] = uint32(b[15]>>32) >> 25
+ tmp[17] += uint32(b[16]) >> 29
+ tmp[17] += uint32(b[16]>>32) << 3
+ tmp[17] += carry
+
+ for i := 0; ; i += 2 {
+
+ tmp[i+1] += tmp[i] >> 29
+ x = tmp[i] & bottom29Bits
+ tmp[i] = 0
+ if x > 0 {
+ set4 := uint32(0)
+ set7 := uint32(0)
+ xMask = nonZeroToAllOnes(x)
+ tmp[i+2] += (x << 7) & bottom29Bits
+ tmp[i+3] += x >> 22
+ if tmp[i+3] < 0x10000000 {
+ set4 = 1
+ tmp[i+3] += 0x10000000 & xMask
+ tmp[i+3] -= (x << 10) & bottom28Bits
+ } else {
+ tmp[i+3] -= (x << 10) & bottom28Bits
+ }
+ if tmp[i+4] < 0x20000000 {
+ tmp[i+4] += 0x20000000 & xMask
+ tmp[i+4] -= set4 // 借位
+ tmp[i+4] -= x >> 18
+ if tmp[i+5] < 0x10000000 {
+ tmp[i+5] += 0x10000000 & xMask
+ tmp[i+5] -= 1 // 借位
+ if tmp[i+6] < 0x20000000 {
+ set7 = 1
+ tmp[i+6] += 0x20000000 & xMask
+ tmp[i+6] -= 1 // 借位
+ } else {
+ tmp[i+6] -= 1 // 借位
+ }
+ } else {
+ tmp[i+5] -= 1
+ }
+ } else {
+ tmp[i+4] -= set4 // 借位
+ tmp[i+4] -= x >> 18
+ }
+ if tmp[i+7] < 0x10000000 {
+ tmp[i+7] += 0x10000000 & xMask
+ tmp[i+7] -= set7
+ tmp[i+7] -= (x << 24) & bottom28Bits
+ tmp[i+8] += (x << 28) & bottom29Bits
+ if tmp[i+8] < 0x20000000 {
+ tmp[i+8] += 0x20000000 & xMask
+ tmp[i+8] -= 1
+ tmp[i+8] -= x >> 4
+ tmp[i+9] += ((x >> 1) - 1) & xMask
+ } else {
+ tmp[i+8] -= 1
+ tmp[i+8] -= x >> 4
+ tmp[i+9] += (x >> 1) & xMask
+ }
+ } else {
+ tmp[i+7] -= set7 // 借位
+ tmp[i+7] -= (x << 24) & bottom28Bits
+ tmp[i+8] += (x << 28) & bottom29Bits
+ if tmp[i+8] < 0x20000000 {
+ tmp[i+8] += 0x20000000 & xMask
+ tmp[i+8] -= x >> 4
+ tmp[i+9] += ((x >> 1) - 1) & xMask
+ } else {
+ tmp[i+8] -= x >> 4
+ tmp[i+9] += (x >> 1) & xMask
+ }
+ }
+
+ }
+
+ if i+1 == 9 {
+ break
+ }
+
+ tmp[i+2] += tmp[i+1] >> 28
+ x = tmp[i+1] & bottom28Bits
+ tmp[i+1] = 0
+ if x > 0 {
+ set5 := uint32(0)
+ set8 := uint32(0)
+ set9 := uint32(0)
+ xMask = nonZeroToAllOnes(x)
+ tmp[i+3] += (x << 7) & bottom28Bits
+ tmp[i+4] += x >> 21
+ if tmp[i+4] < 0x20000000 {
+ set5 = 1
+ tmp[i+4] += 0x20000000 & xMask
+ tmp[i+4] -= (x << 11) & bottom29Bits
+ } else {
+ tmp[i+4] -= (x << 11) & bottom29Bits
+ }
+ if tmp[i+5] < 0x10000000 {
+ tmp[i+5] += 0x10000000 & xMask
+ tmp[i+5] -= set5 // 借位
+ tmp[i+5] -= x >> 18
+ if tmp[i+6] < 0x20000000 {
+ tmp[i+6] += 0x20000000 & xMask
+ tmp[i+6] -= 1 // 借位
+ if tmp[i+7] < 0x10000000 {
+ set8 = 1
+ tmp[i+7] += 0x10000000 & xMask
+ tmp[i+7] -= 1 // 借位
+ } else {
+ tmp[i+7] -= 1 // 借位
+ }
+ } else {
+ tmp[i+6] -= 1 // 借位
+ }
+ } else {
+ tmp[i+5] -= set5 // 借位
+ tmp[i+5] -= x >> 18
+ }
+ if tmp[i+8] < 0x20000000 {
+ set9 = 1
+ tmp[i+8] += 0x20000000 & xMask
+ tmp[i+8] -= set8
+ tmp[i+8] -= (x << 25) & bottom29Bits
+ } else {
+ tmp[i+8] -= set8
+ tmp[i+8] -= (x << 25) & bottom29Bits
+ }
+ if tmp[i+9] < 0x10000000 {
+ tmp[i+9] += 0x10000000 & xMask
+ tmp[i+9] -= set9 // 借位
+ tmp[i+9] -= x >> 4
+ tmp[i+10] += (x - 1) & xMask
+ } else {
+ tmp[i+9] -= set9 // 借位
+ tmp[i+9] -= x >> 4
+ tmp[i+10] += x & xMask
+ }
+ }
+ }
+
+ carry = uint32(0)
+ for i := 0; i < 8; i++ {
+ a[i] = tmp[i+9]
+ a[i] += carry
+ a[i] += (tmp[i+10] << 28) & bottom29Bits
+ carry = a[i] >> 29
+ a[i] &= bottom29Bits
+
+ i++
+ a[i] = tmp[i+9] >> 1
+ a[i] += carry
+ carry = a[i] >> 28
+ a[i] &= bottom28Bits
+ }
+ a[8] = tmp[17]
+ a[8] += carry
+ carry = a[8] >> 29
+ a[8] &= bottom29Bits
+ sm2P256ReduceCarry(a, carry)
+}
+
+// b = a
+func sm2P256Dup(b, a *sm2P256FieldElement) {
+ *b = *a
+}
+
+// X = a * R mod P
+func sm2P256FromBig(X *sm2P256FieldElement, a *big.Int) {
+ x := new(big.Int).Lsh(a, 257)
+ x.Mod(x, sm2P256.P)
+ for i := 0; i < 9; i++ {
+ if bits := x.Bits(); len(bits) > 0 {
+ X[i] = uint32(bits[0]) & bottom29Bits
+ } else {
+ X[i] = 0
+ }
+ x.Rsh(x, 29)
+ i++
+ if i == 9 {
+ break
+ }
+ if bits := x.Bits(); len(bits) > 0 {
+ X[i] = uint32(bits[0]) & bottom28Bits
+ } else {
+ X[i] = 0
+ }
+ x.Rsh(x, 28)
+ }
+}
+
+// X = r * R mod P
+// r = X * R' mod P
+func sm2P256ToBig(X *sm2P256FieldElement) *big.Int {
+ r, tm := new(big.Int), new(big.Int)
+ r.SetInt64(int64(X[8]))
+ for i := 7; i >= 0; i-- {
+ if (i & 1) == 0 {
+ r.Lsh(r, 29)
+ } else {
+ r.Lsh(r, 28)
+ }
+ tm.SetInt64(int64(X[i]))
+ r.Add(r, tm)
+ }
+ r.Mul(r, sm2P256.RInverse)
+ r.Mod(r, sm2P256.P)
+ return r
+}
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