diff --git a/Classes/FCryptoEC_Prime.uc b/Classes/FCryptoEC_Prime.uc
index 8454c78..3dfd037 100644
--- a/Classes/FCryptoEC_Prime.uc
+++ b/Classes/FCryptoEC_Prime.uc
@@ -29,6 +29,187 @@ class FCryptoEC_Prime extends Object
     abstract
     notplaceable;
 
+`include(FCrypto\Classes\FCryptoMacros.uci);
+
+/*
+ * Parameters for supported curves:
+ *   - field modulus p
+ *   - R^2 mod p (R = 2^(15k) for the smallest k such that R >= p)
+ *   - b*R mod p (b is the second curve equation parameter)
+ */
+
+var const array<int> P256_P;
+var const array<int> P256_R2;
+var const array<int> P256_B;
+var const array<int> P384_P;
+var const array<int> P384_R2;
+var const array<int> P384_B;
+var const array<int> P521_P;
+var const array<int> P521_R2;
+var const array<int> P521_B;
+
+struct CurveParams
+{
+    var const array<int> P;
+    var const array<int> B;
+    var const array<int> R2;
+    var const int P0i;
+    var const int PointLen;
+};
+
+var const array<CurveParams> _PP;
+
+static final function CurveParams IdToCurve(FCryptoEllipticCurve Curve)
+{
+    return _PP[Curve - FCEC_Secp256r1];
+};
+
 `define I15_LEN   ((`BR_MAX_EC_SIZE + 29) / 15)
 
-`include(FCrypto\Classes\FCryptoMacros.uci);
+// Montgomery representation. Workaround dummy container type
+// for Jacobian struct due to UScript not having nested arrays.
+struct _Monty
+{
+    var int X[`I15_LEN];
+};
+
+/*
+ * Type for a point in Jacobian coordinates:
+ * -- three values, x, y and z, in Montgomery representation
+ * -- affine coordinates are X = x / z^2 and Y = y / z^3
+ * -- for the point at infinity, z = 0
+ */
+struct Jacobian
+{
+    // uint16_t c[3][I15_LEN];
+    var _Monty C[3];
+};
+
+/*
+ * We use a custom interpreter that uses a dozen registers, and
+ * only six operations:
+ *    MSET(d, a)       copy a into d
+ *    MADD(d, a)       d = d+a (modular)
+ *    MSUB(d, a)       d = d-a (modular)
+ *    MMUL(d, a, b)    d = a*b (Montgomery multiplication)
+ *    MINV(d, a, b)    invert d modulo p; a and b are used as scratch registers
+ *    MTZ(d)           clear return value if d = 0
+ * Destination of MMUL (d) must be distinct from operands (a and b).
+ * There is no such constraint for MSUB and MADD.
+ *
+ * Registers include the operand coordinates, and temporaries.
+ */
+`define MSET(d, a)      (0x0000 + ((`d) << 8) + ((`a) << 4))
+`define MADD(d, a)      (0x1000 + ((`d) << 8) + ((`a) << 4))
+`define MSUB(d, a)      (0x2000 + ((`d) << 8) + ((`a) << 4))
+`define MMUL(d, a, b)   (0x3000 + ((`d) << 8) + ((`a) << 4) + (`b))
+`define MINV(d, a, b)   (0x4000 + ((`d) << 8) + ((`a) << 4) + (`b))
+`define MTZ(d)          (0x5000 + ((`d) << 8))
+`define ENDCODE         0
+
+/*
+ * Registers for the input operands.
+ */
+`define P1x    0
+`define P1y    1
+`define P1z    2
+`define P2x    3
+`define P2y    4
+`define P2z    5
+
+/*
+ * Alternate names for the first input operand.
+ */
+`define Px     0
+`define Py     1
+`define Pz     2
+
+/*
+ * Temporaries.
+ */
+`define T1     6
+`define T2     7
+`define T3     8
+`define T4     9
+`define T5    10
+`define T6    11
+`define T7    12
+
+/*
+ * Extra scratch registers available when there is no second operand (e.g.
+ * for "double" and "affine").
+ */
+`define T8     3
+`define T9     4
+`define T10    5
+
+DefaultProperties
+{
+    P256_P={(
+        0x0111,
+        0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x003F, 0x0000,
+        0x0000, 0x0000, 0x0000, 0x0000, 0x1000, 0x0000, 0x4000, 0x7FFF,
+        0x7FFF, 0x0001
+    )}
+    P256_R2={(
+        0x0111,
+        0x0000, 0x6000, 0x0000, 0x0000, 0x0000, 0x0000, 0x7FFC, 0x7FFF,
+        0x7FBF, 0x7FFF, 0x7FBF, 0x7FFF, 0x7FFF, 0x7FFF, 0x77FF, 0x7FFF,
+        0x4FFF, 0x0000
+    )}
+    P256_B={(
+        0x0111,
+        0x770C, 0x5EEF, 0x29C4, 0x3EC4, 0x6273, 0x0486, 0x4543, 0x3993,
+        0x3C01, 0x6B56, 0x212E, 0x57EE, 0x4882, 0x204B, 0x7483, 0x3C16,
+        0x0187, 0x0000
+    )}
+    P384_P={(
+        0x0199,
+        0x7FFF, 0x7FFF, 0x0003, 0x0000, 0x0000, 0x0000, 0x7FC0, 0x7FFF,
+        0x7EFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF,
+        0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF,
+        0x7FFF, 0x01FF
+    )}
+    P384_R2={(
+        0x0199,
+        0x1000, 0x0000, 0x0000, 0x7FFF, 0x7FFF, 0x0001, 0x0000, 0x0010,
+        0x0000, 0x0000, 0x0000, 0x7F00, 0x7FFF, 0x01FF, 0x0000, 0x1000,
+        0x0000, 0x2000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
+        0x0000, 0x0000
+    )}
+    P384_B={(
+        0x0199,
+        0x7333, 0x2096, 0x70D1, 0x2310, 0x3020, 0x6197, 0x1464, 0x35BB,
+        0x70CA, 0x0117, 0x1920, 0x4136, 0x5FC8, 0x5713, 0x4938, 0x7DD2,
+        0x4DD2, 0x4A71, 0x0220, 0x683E, 0x2C87, 0x4DB1, 0x7BFF, 0x6C09,
+        0x0452, 0x0084
+    )}
+    P521_P={(
+        0x022B,
+        0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF,
+        0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF,
+        0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF,
+        0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF,
+        0x7FFF, 0x7FFF, 0x07FF
+    )}
+    P521_R2={(
+        0x022B,
+        0x0100, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
+        0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
+        0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
+        0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
+        0x0000, 0x0000, 0x0000
+    )}
+    P521_B={(
+        0x022B,
+        0x7002, 0x6A07, 0x751A, 0x228F, 0x71EF, 0x5869, 0x20F4, 0x1EFC,
+        0x7357, 0x37E0, 0x4EEC, 0x605E, 0x1652, 0x26F6, 0x31FA, 0x4A8F,
+        0x6193, 0x3C2A, 0x3C42, 0x48C7, 0x3489, 0x6771, 0x4C57, 0x5CCD,
+        0x2725, 0x545B, 0x503B, 0x5B42, 0x21A0, 0x2534, 0x687E, 0x70E4,
+        0x1618, 0x27D7, 0x0465
+    )}
+
+    _PP(0)=(P=P256_P, B=P256_B, R2=P256R2, P0i=0x001, PointLen=65)
+    _PP(1)=(P=P384_P, B=P384_B, R2=P384R2, P0i=0x001, PointLen=97)
+    _PP(2)=(P=P521_P, B=P521_B, R2=P521R2, P0i=0x001, PointLen=133)
+}