diff options
Diffstat (limited to 'core/src/main/java/org/spongycastle/math/ec/custom/sec/SecP256R1Field.java')
| -rw-r--r-- | core/src/main/java/org/spongycastle/math/ec/custom/sec/SecP256R1Field.java | 312 |
1 files changed, 312 insertions, 0 deletions
diff --git a/core/src/main/java/org/spongycastle/math/ec/custom/sec/SecP256R1Field.java b/core/src/main/java/org/spongycastle/math/ec/custom/sec/SecP256R1Field.java new file mode 100644 index 00000000..78c15d17 --- /dev/null +++ b/core/src/main/java/org/spongycastle/math/ec/custom/sec/SecP256R1Field.java @@ -0,0 +1,312 @@ +package org.spongycastle.math.ec.custom.sec; + +import java.math.BigInteger; + +import org.spongycastle.math.raw.Nat; +import org.spongycastle.math.raw.Nat256; + +public class SecP256R1Field +{ + private static final long M = 0xFFFFFFFFL; + + // 2^256 - 2^224 + 2^192 + 2^96 - 1 + static final int[] P = new int[]{ 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0x00000000, 0x00000000, 0x00000000, + 0x00000001, 0xFFFFFFFF }; + static final int[] PExt = new int[]{ 0x00000001, 0x00000000, 0x00000000, 0xFFFFFFFE, 0xFFFFFFFF, + 0xFFFFFFFF, 0xFFFFFFFE, 0x00000001, 0xFFFFFFFE, 0x00000001, 0xFFFFFFFE, 0x00000001, 0x00000001, 0xFFFFFFFE, + 0x00000002, 0xFFFFFFFE }; + private static final int P7 = 0xFFFFFFFF; + private static final int PExt15 = 0xFFFFFFFF; + + public static void add(int[] x, int[] y, int[] z) + { + int c = Nat256.add(x, y, z); + if (c != 0 || (z[7] == P7 && Nat256.gte(z, P))) + { + addPInvTo(z); + } + } + + public static void addExt(int[] xx, int[] yy, int[] zz) + { + int c = Nat.add(16, xx, yy, zz); + if (c != 0 || ((zz[15] & PExt15) == PExt15 && Nat.gte(16, zz, PExt))) + { + Nat.subFrom(16, PExt, zz); + } + } + + public static void addOne(int[] x, int[] z) + { + int c = Nat.inc(8, x, z); + if (c != 0 || (z[7] == P7 && Nat256.gte(z, P))) + { + addPInvTo(z); + } + } + + public static int[] fromBigInteger(BigInteger x) + { + int[] z = Nat256.fromBigInteger(x); + if (z[7] == P7 && Nat256.gte(z, P)) + { + Nat256.subFrom(P, z); + } + return z; + } + + public static void half(int[] x, int[] z) + { + if ((x[0] & 1) == 0) + { + Nat.shiftDownBit(8, x, 0, z); + } + else + { + int c = Nat256.add(x, P, z); + Nat.shiftDownBit(8, z, c); + } + } + + public static void multiply(int[] x, int[] y, int[] z) + { + int[] tt = Nat256.createExt(); + Nat256.mul(x, y, tt); + reduce(tt, z); + } + + public static void multiplyAddToExt(int[] x, int[] y, int[] zz) + { + int c = Nat256.mulAddTo(x, y, zz); + if (c != 0 || ((zz[15] & PExt15) == PExt15 && Nat.gte(16, zz, PExt))) + { + Nat.subFrom(16, PExt, zz); + } + } + + public static void negate(int[] x, int[] z) + { + if (Nat256.isZero(x)) + { + Nat256.zero(z); + } + else + { + Nat256.sub(P, x, z); + } + } + + public static void reduce(int[] xx, int[] z) + { + long xx08 = xx[8] & M, xx09 = xx[9] & M, xx10 = xx[10] & M, xx11 = xx[11] & M; + long xx12 = xx[12] & M, xx13 = xx[13] & M, xx14 = xx[14] & M, xx15 = xx[15] & M; + + final long n = 6; + + xx08 -= n; + + long t0 = xx08 + xx09; + long t1 = xx09 + xx10; + long t2 = xx10 + xx11 - xx15; + long t3 = xx11 + xx12; + long t4 = xx12 + xx13; + long t5 = xx13 + xx14; + long t6 = xx14 + xx15; + + long cc = 0; + cc += (xx[0] & M) + t0 - t3 - t5; + z[0] = (int)cc; + cc >>= 32; + cc += (xx[1] & M) + t1 - t4 - t6; + z[1] = (int)cc; + cc >>= 32; + cc += (xx[2] & M) + t2 - t5; + z[2] = (int)cc; + cc >>= 32; + cc += (xx[3] & M) + (t3 << 1) + xx13 - xx15 - t0; + z[3] = (int)cc; + cc >>= 32; + cc += (xx[4] & M) + (t4 << 1) + xx14 - t1; + z[4] = (int)cc; + cc >>= 32; + cc += (xx[5] & M) + (t5 << 1) - t2; + z[5] = (int)cc; + cc >>= 32; + cc += (xx[6] & M) + (t6 << 1) + t5 - t0; + z[6] = (int)cc; + cc >>= 32; + cc += (xx[7] & M) + (xx15 << 1) + xx08 - t2 - t4; + z[7] = (int)cc; + cc >>= 32; + cc += n; + +// assert cc >= 0; + + reduce32((int)cc, z); + } + + public static void reduce32(int x, int[] z) + { + long cc = 0; + + if (x != 0) + { + long xx08 = x & M; + + cc += (z[0] & M) + xx08; + z[0] = (int)cc; + cc >>= 32; + if (cc != 0) + { + cc += (z[1] & M); + z[1] = (int)cc; + cc >>= 32; + cc += (z[2] & M); + z[2] = (int)cc; + cc >>= 32; + } + cc += (z[3] & M) - xx08; + z[3] = (int)cc; + cc >>= 32; + if (cc != 0) + { + cc += (z[4] & M); + z[4] = (int)cc; + cc >>= 32; + cc += (z[5] & M); + z[5] = (int)cc; + cc >>= 32; + } + cc += (z[6] & M) - xx08; + z[6] = (int)cc; + cc >>= 32; + cc += (z[7] & M) + xx08; + z[7] = (int)cc; + cc >>= 32; + +// assert cc == 0 || cc == 1; + } + + if (cc != 0 || (z[7] == P7 && Nat256.gte(z, P))) + { + addPInvTo(z); + } + } + + public static void square(int[] x, int[] z) + { + int[] tt = Nat256.createExt(); + Nat256.square(x, tt); + reduce(tt, z); + } + + public static void squareN(int[] x, int n, int[] z) + { +// assert n > 0; + + int[] tt = Nat256.createExt(); + Nat256.square(x, tt); + reduce(tt, z); + + while (--n > 0) + { + Nat256.square(z, tt); + reduce(tt, z); + } + } + + public static void subtract(int[] x, int[] y, int[] z) + { + int c = Nat256.sub(x, y, z); + if (c != 0) + { + subPInvFrom(z); + } + } + + public static void subtractExt(int[] xx, int[] yy, int[] zz) + { + int c = Nat.sub(16, xx, yy, zz); + if (c != 0) + { + Nat.addTo(16, PExt, zz); + } + } + + public static void twice(int[] x, int[] z) + { + int c = Nat.shiftUpBit(8, x, 0, z); + if (c != 0 || (z[7] == P7 && Nat256.gte(z, P))) + { + addPInvTo(z); + } + } + + private static void addPInvTo(int[] z) + { + long c = (z[0] & M) + 1; + z[0] = (int)c; + c >>= 32; + if (c != 0) + { + c += (z[1] & M); + z[1] = (int)c; + c >>= 32; + c += (z[2] & M); + z[2] = (int)c; + c >>= 32; + } + c += (z[3] & M) - 1; + z[3] = (int)c; + c >>= 32; + if (c != 0) + { + c += (z[4] & M); + z[4] = (int)c; + c >>= 32; + c += (z[5] & M); + z[5] = (int)c; + c >>= 32; + } + c += (z[6] & M) - 1; + z[6] = (int)c; + c >>= 32; + c += (z[7] & M) + 1; + z[7] = (int)c; +// c >>= 32; + } + + private static void subPInvFrom(int[] z) + { + long c = (z[0] & M) - 1; + z[0] = (int)c; + c >>= 32; + if (c != 0) + { + c += (z[1] & M); + z[1] = (int)c; + c >>= 32; + c += (z[2] & M); + z[2] = (int)c; + c >>= 32; + } + c += (z[3] & M) + 1; + z[3] = (int)c; + c >>= 32; + if (c != 0) + { + c += (z[4] & M); + z[4] = (int)c; + c >>= 32; + c += (z[5] & M); + z[5] = (int)c; + c >>= 32; + } + c += (z[6] & M) + 1; + z[6] = (int)c; + c >>= 32; + c += (z[7] & M) - 1; + z[7] = (int)c; +// c >>= 32; + } +} |