1 /* 2 * Copyright (c) 2018, 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.Optional; 36 37 public class ECDSAOperations { 38 39 public static class Seed { 40 private final byte[] seedValue; 41 Seed(byte[] seedValue)42 public Seed(byte[] seedValue) { 43 this.seedValue = seedValue; 44 } 45 getSeedValue()46 public byte[] getSeedValue() { 47 return seedValue; 48 } 49 } 50 51 public static class Nonce { 52 private final byte[] nonceValue; 53 Nonce(byte[] nonceValue)54 public Nonce(byte[] nonceValue) { 55 this.nonceValue = nonceValue; 56 } 57 getNonceValue()58 public byte[] getNonceValue() { 59 return nonceValue; 60 } 61 } 62 63 private final ECOperations ecOps; 64 private final AffinePoint basePoint; 65 ECDSAOperations(ECOperations ecOps, ECPoint basePoint)66 public ECDSAOperations(ECOperations ecOps, ECPoint basePoint) { 67 this.ecOps = ecOps; 68 this.basePoint = toAffinePoint(basePoint, ecOps.getField()); 69 } 70 getEcOperations()71 public ECOperations getEcOperations() { 72 return ecOps; 73 } 74 basePointMultiply(byte[] scalar)75 public AffinePoint basePointMultiply(byte[] scalar) { 76 return ecOps.multiply(basePoint, scalar).asAffine(); 77 } 78 toAffinePoint(ECPoint point, IntegerFieldModuloP field)79 public static AffinePoint toAffinePoint(ECPoint point, 80 IntegerFieldModuloP field) { 81 82 ImmutableIntegerModuloP affineX = field.getElement(point.getAffineX()); 83 ImmutableIntegerModuloP affineY = field.getElement(point.getAffineY()); 84 return new AffinePoint(affineX, affineY); 85 } 86 87 public static forParameters(ECParameterSpec ecParams)88 Optional<ECDSAOperations> forParameters(ECParameterSpec ecParams) { 89 Optional<ECOperations> curveOps = 90 ECOperations.forParameters(ecParams); 91 return curveOps.map( 92 ops -> new ECDSAOperations(ops, ecParams.getGenerator()) 93 ); 94 } 95 96 /** 97 * 98 * Sign a digest using the provided private key and seed. 99 * IMPORTANT: The private key is a scalar represented using a 100 * little-endian byte array. This is backwards from the conventional 101 * representation in ECDSA. The routines that produce and consume this 102 * value uses little-endian, so this deviation from convention removes 103 * the requirement to swap the byte order. The returned signature is in 104 * the conventional byte order. 105 * 106 * @param privateKey the private key scalar as a little-endian byte array 107 * @param digest the digest to be signed 108 * @param seed the seed that will be used to produce the nonce. This object 109 * should contain an array that is at least 64 bits longer than 110 * the number of bits required to represent the group order. 111 * @return the ECDSA signature value 112 * @throws IntermediateValueException if the signature cannot be produced 113 * due to an unacceptable intermediate or final value. If this 114 * exception is thrown, then the caller should discard the nonnce and 115 * try again with an entirely new nonce value. 116 */ signDigest(byte[] privateKey, byte[] digest, Seed seed)117 public byte[] signDigest(byte[] privateKey, byte[] digest, Seed seed) 118 throws IntermediateValueException { 119 120 byte[] nonceArr = ecOps.seedToScalar(seed.getSeedValue()); 121 122 Nonce nonce = new Nonce(nonceArr); 123 return signDigest(privateKey, digest, nonce); 124 } 125 126 /** 127 * 128 * Sign a digest using the provided private key and nonce. 129 * IMPORTANT: The private key and nonce are scalars represented by a 130 * little-endian byte array. This is backwards from the conventional 131 * representation in ECDSA. The routines that produce and consume these 132 * values use little-endian, so this deviation from convention removes 133 * the requirement to swap the byte order. The returned signature is in 134 * the conventional byte order. 135 * 136 * @param privateKey the private key scalar as a little-endian byte array 137 * @param digest the digest to be signed 138 * @param nonce the nonce object containing a little-endian scalar value. 139 * @return the ECDSA signature value 140 * @throws IntermediateValueException if the signature cannot be produced 141 * due to an unacceptable intermediate or final value. If this 142 * exception is thrown, then the caller should discard the nonnce and 143 * try again with an entirely new nonce value. 144 */ signDigest(byte[] privateKey, byte[] digest, Nonce nonce)145 public byte[] signDigest(byte[] privateKey, byte[] digest, Nonce nonce) 146 throws IntermediateValueException { 147 148 IntegerFieldModuloP orderField = ecOps.getOrderField(); 149 int orderBits = orderField.getSize().bitLength(); 150 if (orderBits % 8 != 0 && orderBits < digest.length * 8) { 151 // This implementation does not support truncating digests to 152 // a length that is not a multiple of 8. 153 throw new ProviderException("Invalid digest length"); 154 } 155 156 byte[] k = nonce.getNonceValue(); 157 // check nonce length 158 int length = (orderField.getSize().bitLength() + 7) / 8; 159 if (k.length != length) { 160 throw new ProviderException("Incorrect nonce length"); 161 } 162 163 MutablePoint R = ecOps.multiply(basePoint, k); 164 IntegerModuloP r = R.asAffine().getX(); 165 // put r into the correct field by fully reducing to an array 166 byte[] temp = new byte[length]; 167 r.asByteArray(temp); 168 r = orderField.getElement(temp); 169 // store r in result 170 r.asByteArray(temp); 171 byte[] result = new byte[2 * length]; 172 ArrayUtil.reverse(temp); 173 System.arraycopy(temp, 0, result, 0, length); 174 // compare r to 0 175 if (ECOperations.allZero(temp)) { 176 throw new IntermediateValueException(); 177 } 178 179 IntegerModuloP dU = orderField.getElement(privateKey); 180 int lengthE = Math.min(length, digest.length); 181 byte[] E = new byte[lengthE]; 182 System.arraycopy(digest, 0, E, 0, lengthE); 183 ArrayUtil.reverse(E); 184 IntegerModuloP e = orderField.getElement(E); 185 IntegerModuloP kElem = orderField.getElement(k); 186 IntegerModuloP kInv = kElem.multiplicativeInverse(); 187 MutableIntegerModuloP s = r.mutable(); 188 s.setProduct(dU).setSum(e).setProduct(kInv); 189 // store s in result 190 s.asByteArray(temp); 191 ArrayUtil.reverse(temp); 192 System.arraycopy(temp, 0, result, length, length); 193 // compare s to 0 194 if (ECOperations.allZero(temp)) { 195 throw new IntermediateValueException(); 196 } 197 198 return result; 199 200 } 201 202 } 203