1 /* 2 * Copyright (c) 2018, 2020, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package sun.security.ec; 27 28 import sun.security.ec.point.*; 29 import sun.security.util.ArrayUtil; 30 import sun.security.util.math.*; 31 import static sun.security.ec.ECOperations.IntermediateValueException; 32 33 import java.security.ProviderException; 34 import java.security.spec.*; 35 import java.util.Arrays; 36 import java.util.Optional; 37 38 public class ECDSAOperations { 39 40 public static class Seed { 41 private final byte[] seedValue; 42 Seed(byte[] seedValue)43 public Seed(byte[] seedValue) { 44 this.seedValue = seedValue; 45 } 46 getSeedValue()47 public byte[] getSeedValue() { 48 return seedValue; 49 } 50 } 51 52 public static class Nonce { 53 private final byte[] nonceValue; 54 Nonce(byte[] nonceValue)55 public Nonce(byte[] nonceValue) { 56 this.nonceValue = nonceValue; 57 } 58 getNonceValue()59 public byte[] getNonceValue() { 60 return nonceValue; 61 } 62 } 63 64 private final ECOperations ecOps; 65 private final AffinePoint basePoint; 66 ECDSAOperations(ECOperations ecOps, ECPoint basePoint)67 public ECDSAOperations(ECOperations ecOps, ECPoint basePoint) { 68 this.ecOps = ecOps; 69 this.basePoint = toAffinePoint(basePoint, ecOps.getField()); 70 } 71 getEcOperations()72 public ECOperations getEcOperations() { 73 return ecOps; 74 } 75 basePointMultiply(byte[] scalar)76 public AffinePoint basePointMultiply(byte[] scalar) { 77 return ecOps.multiply(basePoint, scalar).asAffine(); 78 } 79 toAffinePoint(ECPoint point, IntegerFieldModuloP field)80 public static AffinePoint toAffinePoint(ECPoint point, 81 IntegerFieldModuloP field) { 82 83 ImmutableIntegerModuloP affineX = field.getElement(point.getAffineX()); 84 ImmutableIntegerModuloP affineY = field.getElement(point.getAffineY()); 85 return new AffinePoint(affineX, affineY); 86 } 87 88 public static forParameters(ECParameterSpec ecParams)89 Optional<ECDSAOperations> forParameters(ECParameterSpec ecParams) { 90 Optional<ECOperations> curveOps = 91 ECOperations.forParameters(ecParams); 92 return curveOps.map( 93 ops -> new ECDSAOperations(ops, ecParams.getGenerator()) 94 ); 95 } 96 97 /** 98 * 99 * Sign a digest using the provided private key and seed. 100 * IMPORTANT: The private key is a scalar represented using a 101 * little-endian byte array. This is backwards from the conventional 102 * representation in ECDSA. The routines that produce and consume this 103 * value uses little-endian, so this deviation from convention removes 104 * the requirement to swap the byte order. The returned signature is in 105 * the conventional byte order. 106 * 107 * @param privateKey the private key scalar as a little-endian byte array 108 * @param digest the digest to be signed 109 * @param seed the seed that will be used to produce the nonce. This object 110 * should contain an array that is at least 64 bits longer than 111 * the number of bits required to represent the group order. 112 * @return the ECDSA signature value 113 * @throws IntermediateValueException if the signature cannot be produced 114 * due to an unacceptable intermediate or final value. If this 115 * exception is thrown, then the caller should discard the nonnce and 116 * try again with an entirely new nonce value. 117 */ signDigest(byte[] privateKey, byte[] digest, Seed seed)118 public byte[] signDigest(byte[] privateKey, byte[] digest, Seed seed) 119 throws IntermediateValueException { 120 121 byte[] nonceArr = ecOps.seedToScalar(seed.getSeedValue()); 122 123 Nonce nonce = new Nonce(nonceArr); 124 return signDigest(privateKey, digest, nonce); 125 } 126 127 /** 128 * 129 * Sign a digest using the provided private key and nonce. 130 * IMPORTANT: The private key and nonce are scalars represented by a 131 * little-endian byte array. This is backwards from the conventional 132 * representation in ECDSA. The routines that produce and consume these 133 * values use little-endian, so this deviation from convention removes 134 * the requirement to swap the byte order. The returned signature is in 135 * the conventional byte order. 136 * 137 * @param privateKey the private key scalar as a little-endian byte array 138 * @param digest the digest to be signed 139 * @param nonce the nonce object containing a little-endian scalar value. 140 * @return the ECDSA signature value 141 * @throws IntermediateValueException if the signature cannot be produced 142 * due to an unacceptable intermediate or final value. If this 143 * exception is thrown, then the caller should discard the nonnce and 144 * try again with an entirely new nonce value. 145 */ signDigest(byte[] privateKey, byte[] digest, Nonce nonce)146 public byte[] signDigest(byte[] privateKey, byte[] digest, Nonce nonce) 147 throws IntermediateValueException { 148 149 IntegerFieldModuloP orderField = ecOps.getOrderField(); 150 int orderBits = orderField.getSize().bitLength(); 151 if (orderBits % 8 != 0 && orderBits < digest.length * 8) { 152 // This implementation does not support truncating digests to 153 // a length that is not a multiple of 8. 154 throw new ProviderException("Invalid digest length"); 155 } 156 157 byte[] k = nonce.getNonceValue(); 158 // check nonce length 159 int length = (orderField.getSize().bitLength() + 7) / 8; 160 if (k.length != length) { 161 throw new ProviderException("Incorrect nonce length"); 162 } 163 164 MutablePoint R = ecOps.multiply(basePoint, k); 165 IntegerModuloP r = R.asAffine().getX(); 166 // put r into the correct field by fully reducing to an array 167 byte[] temp = new byte[length]; 168 r = b2a(r, orderField, temp); 169 byte[] result = new byte[2 * length]; 170 ArrayUtil.reverse(temp); 171 System.arraycopy(temp, 0, result, 0, length); 172 // compare r to 0 173 if (ECOperations.allZero(temp)) { 174 throw new IntermediateValueException(); 175 } 176 177 IntegerModuloP dU = orderField.getElement(privateKey); 178 int lengthE = Math.min(length, digest.length); 179 byte[] E = new byte[lengthE]; 180 System.arraycopy(digest, 0, E, 0, lengthE); 181 ArrayUtil.reverse(E); 182 IntegerModuloP e = orderField.getElement(E); 183 IntegerModuloP kElem = orderField.getElement(k); 184 IntegerModuloP kInv = kElem.multiplicativeInverse(); 185 MutableIntegerModuloP s = r.mutable(); 186 s.setProduct(dU).setSum(e).setProduct(kInv); 187 // store s in result 188 s.asByteArray(temp); 189 ArrayUtil.reverse(temp); 190 System.arraycopy(temp, 0, result, length, length); 191 // compare s to 0 192 if (ECOperations.allZero(temp)) { 193 throw new IntermediateValueException(); 194 } 195 196 return result; 197 198 } verifySignedDigest(byte[] digest, byte[] sig, ECPoint pp)199 public boolean verifySignedDigest(byte[] digest, byte[] sig, ECPoint pp) { 200 201 IntegerFieldModuloP field = ecOps.getField(); 202 IntegerFieldModuloP orderField = ecOps.getOrderField(); 203 int length = (orderField.getSize().bitLength() + 7) / 8; 204 205 byte[] r; 206 byte[] s; 207 208 int encodeLength = sig.length / 2; 209 if (sig.length %2 != 0 || encodeLength > length) { 210 return false; 211 } else if (encodeLength == length) { 212 r = Arrays.copyOf(sig, length); 213 s = Arrays.copyOfRange(sig, length, length * 2); 214 } else { 215 r = new byte[length]; 216 s = new byte[length]; 217 System.arraycopy(sig, 0, r, length - encodeLength, encodeLength); 218 System.arraycopy(sig, encodeLength, s, length - encodeLength, encodeLength); 219 } 220 221 ArrayUtil.reverse(r); 222 ArrayUtil.reverse(s); 223 IntegerModuloP ri = orderField.getElement(r); 224 IntegerModuloP si = orderField.getElement(s); 225 // z 226 int lengthE = Math.min(length, digest.length); 227 byte[] E = new byte[lengthE]; 228 System.arraycopy(digest, 0, E, 0, lengthE); 229 ArrayUtil.reverse(E); 230 IntegerModuloP e = orderField.getElement(E); 231 232 IntegerModuloP sInv = si.multiplicativeInverse(); 233 ImmutableIntegerModuloP u1 = e.multiply(sInv); 234 ImmutableIntegerModuloP u2 = ri.multiply(sInv); 235 236 AffinePoint pub = new AffinePoint(field.getElement(pp.getAffineX()), 237 field.getElement(pp.getAffineY())); 238 239 byte[] temp1 = new byte[length]; 240 b2a(u1, orderField, temp1); 241 242 byte[] temp2 = new byte[length]; 243 b2a(u2, orderField, temp2); 244 245 MutablePoint p1 = ecOps.multiply(basePoint, temp1); 246 MutablePoint p2 = ecOps.multiply(pub, temp2); 247 248 ecOps.setSum(p1, p2.asAffine()); 249 IntegerModuloP result = p1.asAffine().getX(); 250 result = result.additiveInverse().add(ri); 251 252 b2a(result, orderField, temp1); 253 return ECOperations.allZero(temp1); 254 } 255 b2a(IntegerModuloP b, IntegerFieldModuloP orderField, byte[] temp1)256 static public ImmutableIntegerModuloP b2a(IntegerModuloP b, 257 IntegerFieldModuloP orderField, byte[] temp1) { 258 b.asByteArray(temp1); 259 ImmutableIntegerModuloP b2 = orderField.getElement(temp1); 260 b2.asByteArray(temp1); 261 return b2; 262 } 263 } 264