1package org.bouncycastle.math.ec.custom.sec; 2 3import java.math.BigInteger; 4 5import org.bouncycastle.math.ec.ECFieldElement; 6import org.bouncycastle.math.raw.Mod; 7import org.bouncycastle.math.raw.Nat; 8import org.bouncycastle.math.raw.Nat224; 9import org.bouncycastle.util.Arrays; 10 11public class SecP224R1FieldElement extends ECFieldElement 12{ 13 public static final BigInteger Q = SecP224R1Curve.q; 14 15 protected int[] x; 16 17 public SecP224R1FieldElement(BigInteger x) 18 { 19 if (x == null || x.signum() < 0 || x.compareTo(Q) >= 0) 20 { 21 throw new IllegalArgumentException("x value invalid for SecP224R1FieldElement"); 22 } 23 24 this.x = SecP224R1Field.fromBigInteger(x); 25 } 26 27 public SecP224R1FieldElement() 28 { 29 this.x = Nat224.create(); 30 } 31 32 protected SecP224R1FieldElement(int[] x) 33 { 34 this.x = x; 35 } 36 37 public boolean isZero() 38 { 39 return Nat224.isZero(x); 40 } 41 42 public boolean isOne() 43 { 44 return Nat224.isOne(x); 45 } 46 47 public boolean testBitZero() 48 { 49 return Nat224.getBit(x, 0) == 1; 50 } 51 52 public BigInteger toBigInteger() 53 { 54 return Nat224.toBigInteger(x); 55 } 56 57 public String getFieldName() 58 { 59 return "SecP224R1Field"; 60 } 61 62 public int getFieldSize() 63 { 64 return Q.bitLength(); 65 } 66 67 public ECFieldElement add(ECFieldElement b) 68 { 69 int[] z = Nat224.create(); 70 SecP224R1Field.add(x, ((SecP224R1FieldElement)b).x, z); 71 return new SecP224R1FieldElement(z); 72 } 73 74 public ECFieldElement addOne() 75 { 76 int[] z = Nat224.create(); 77 SecP224R1Field.addOne(x, z); 78 return new SecP224R1FieldElement(z); 79 } 80 81 public ECFieldElement subtract(ECFieldElement b) 82 { 83 int[] z = Nat224.create(); 84 SecP224R1Field.subtract(x, ((SecP224R1FieldElement)b).x, z); 85 return new SecP224R1FieldElement(z); 86 } 87 88 public ECFieldElement multiply(ECFieldElement b) 89 { 90 int[] z = Nat224.create(); 91 SecP224R1Field.multiply(x, ((SecP224R1FieldElement)b).x, z); 92 return new SecP224R1FieldElement(z); 93 } 94 95 public ECFieldElement divide(ECFieldElement b) 96 { 97// return multiply(b.invert()); 98 int[] z = Nat224.create(); 99 Mod.invert(SecP224R1Field.P, ((SecP224R1FieldElement)b).x, z); 100 SecP224R1Field.multiply(z, x, z); 101 return new SecP224R1FieldElement(z); 102 } 103 104 public ECFieldElement negate() 105 { 106 int[] z = Nat224.create(); 107 SecP224R1Field.negate(x, z); 108 return new SecP224R1FieldElement(z); 109 } 110 111 public ECFieldElement square() 112 { 113 int[] z = Nat224.create(); 114 SecP224R1Field.square(x, z); 115 return new SecP224R1FieldElement(z); 116 } 117 118 public ECFieldElement invert() 119 { 120// return new SecP224R1FieldElement(toBigInteger().modInverse(Q)); 121 int[] z = Nat224.create(); 122 Mod.invert(SecP224R1Field.P, x, z); 123 return new SecP224R1FieldElement(z); 124 } 125 126 /** 127 * return a sqrt root - the routine verifies that the calculation returns the right value - if 128 * none exists it returns null. 129 */ 130 public ECFieldElement sqrt() 131 { 132 int[] c = this.x; 133 if (Nat224.isZero(c) || Nat224.isOne(c)) 134 { 135 return this; 136 } 137 138 int[] nc = Nat224.create(); 139 SecP224R1Field.negate(c, nc); 140 141 int[] r = Mod.random(SecP224R1Field.P); 142 int[] t = Nat224.create(); 143 144 if (!isSquare(c)) 145 { 146 return null; 147 } 148 149 while (!trySqrt(nc, r, t)) 150 { 151 SecP224R1Field.addOne(r, r); 152 } 153 154 SecP224R1Field.square(t, r); 155 156 return Nat224.eq(c, r) ? new SecP224R1FieldElement(t) : null; 157 } 158 159 public boolean equals(Object other) 160 { 161 if (other == this) 162 { 163 return true; 164 } 165 166 if (!(other instanceof SecP224R1FieldElement)) 167 { 168 return false; 169 } 170 171 SecP224R1FieldElement o = (SecP224R1FieldElement)other; 172 return Nat224.eq(x, o.x); 173 } 174 175 public int hashCode() 176 { 177 return Q.hashCode() ^ Arrays.hashCode(x, 0, 7); 178 } 179 180 private static boolean isSquare(int[] x) 181 { 182 int[] t1 = Nat224.create(); 183 int[] t2 = Nat224.create(); 184 Nat224.copy(x, t1); 185 186 for (int i = 0; i < 7; ++i) 187 { 188 Nat224.copy(t1, t2); 189 SecP224R1Field.squareN(t1, 1 << i, t1); 190 SecP224R1Field.multiply(t1, t2, t1); 191 } 192 193 SecP224R1Field.squareN(t1, 95, t1); 194 return Nat224.isOne(t1); 195 } 196 197 private static void RM(int[] nc, int[] d0, int[] e0, int[] d1, int[] e1, int[] f1, int[] t) 198 { 199 SecP224R1Field.multiply(e1, e0, t); 200 SecP224R1Field.multiply(t, nc, t); 201 SecP224R1Field.multiply(d1, d0, f1); 202 SecP224R1Field.add(f1, t, f1); 203 SecP224R1Field.multiply(d1, e0, t); 204 Nat224.copy(f1, d1); 205 SecP224R1Field.multiply(e1, d0, e1); 206 SecP224R1Field.add(e1, t, e1); 207 SecP224R1Field.square(e1, f1); 208 SecP224R1Field.multiply(f1, nc, f1); 209 } 210 211 private static void RP(int[] nc, int[] d1, int[] e1, int[] f1, int[] t) 212 { 213 Nat224.copy(nc, f1); 214 215 int[] d0 = Nat224.create(); 216 int[] e0 = Nat224.create(); 217 218 for (int i = 0; i < 7; ++i) 219 { 220 Nat224.copy(d1, d0); 221 Nat224.copy(e1, e0); 222 223 int j = 1 << i; 224 while (--j >= 0) 225 { 226 RS(d1, e1, f1, t); 227 } 228 229 RM(nc, d0, e0, d1, e1, f1, t); 230 } 231 } 232 233 private static void RS(int[] d, int[] e, int[] f, int[] t) 234 { 235 SecP224R1Field.multiply(e, d, e); 236 SecP224R1Field.twice(e, e); 237 SecP224R1Field.square(d, t); 238 SecP224R1Field.add(f, t, d); 239 SecP224R1Field.multiply(f, t, f); 240 int c = Nat.shiftUpBits(7, f, 2, 0); 241 SecP224R1Field.reduce32(c, f); 242 } 243 244 private static boolean trySqrt(int[] nc, int[] r, int[] t) 245 { 246 int[] d1 = Nat224.create(); 247 Nat224.copy(r, d1); 248 int[] e1 = Nat224.create(); 249 e1[0] = 1; 250 int[] f1 = Nat224.create(); 251 RP(nc, d1, e1, f1, t); 252 253 int[] d0 = Nat224.create(); 254 int[] e0 = Nat224.create(); 255 256 for (int k = 1; k < 96; ++k) 257 { 258 Nat224.copy(d1, d0); 259 Nat224.copy(e1, e0); 260 261 RS(d1, e1, f1, t); 262 263 if (Nat224.isZero(d1)) 264 { 265 Mod.invert(SecP224R1Field.P, e0, t); 266 SecP224R1Field.multiply(t, d0, t); 267 return true; 268 } 269 } 270 271 return false; 272 } 273} 274