Alan Viverette | 3da604b | 2020-06-10 18:34:39 +0000 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2019 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package com.android.internal.net.ipsec.ike.crypto; |
| 18 | |
| 19 | import android.net.ipsec.ike.SaProposal; |
| 20 | |
| 21 | import com.android.internal.net.crypto.KeyGenerationUtils; |
| 22 | import com.android.internal.net.ipsec.ike.message.IkeSaPayload.PrfTransform; |
| 23 | |
| 24 | import java.nio.ByteBuffer; |
| 25 | import java.util.Arrays; |
| 26 | |
| 27 | import javax.crypto.Cipher; |
| 28 | import javax.crypto.Mac; |
| 29 | |
| 30 | /** |
| 31 | * IkeMacPrf represents a negotiated pseudorandom function. |
| 32 | * |
| 33 | * <p>Pseudorandom function is usually used for IKE SA authentication and generating keying |
| 34 | * materials. |
| 35 | * |
| 36 | * <p>For pseudorandom functions based on integrity algorithms, all operations will be done by a |
| 37 | * {@link Mac}. For pseudorandom functions based on encryption algorithms, all operations will be |
| 38 | * done by a {@link Cipher}. |
| 39 | * |
| 40 | * @see <a href="https://tools.ietf.org/html/rfc7296#section-3.3.2">RFC 7296, Internet Key Exchange |
| 41 | * Protocol Version 2 (IKEv2)</a> |
| 42 | */ |
| 43 | public class IkeMacPrf extends IkeMac { |
| 44 | // STOPSHIP: b/130190639 Catch unchecked exceptions, notify users and close the IKE session. |
| 45 | private static final int PSEUDORANDOM_FUNCTION_AES128_XCBC_KEY_LEN = 16; |
| 46 | |
| 47 | private IkeMacPrf( |
| 48 | @SaProposal.PseudorandomFunction int algorithmId, |
| 49 | int keyLength, |
| 50 | String algorithmName, |
| 51 | boolean isEncryptAlgo) { |
| 52 | super(algorithmId, keyLength, algorithmName, isEncryptAlgo); |
| 53 | } |
| 54 | |
| 55 | /** |
| 56 | * Construct an instance of IkeMacPrf. |
| 57 | * |
| 58 | * @param prfTransform the valid negotiated PrfTransform. |
| 59 | * @return an instance of IkeMacPrf. |
| 60 | */ |
| 61 | public static IkeMacPrf create(PrfTransform prfTransform) { |
| 62 | int algorithmId = prfTransform.id; |
| 63 | |
| 64 | int keyLength = 0; |
| 65 | String algorithmName = ""; |
| 66 | boolean isEncryptAlgo = false; |
| 67 | |
| 68 | switch (algorithmId) { |
| 69 | case SaProposal.PSEUDORANDOM_FUNCTION_HMAC_SHA1: |
| 70 | keyLength = 20; |
| 71 | algorithmName = "HmacSHA1"; |
| 72 | break; |
| 73 | case SaProposal.PSEUDORANDOM_FUNCTION_AES128_XCBC: |
| 74 | keyLength = 16; |
| 75 | isEncryptAlgo = true; |
| 76 | algorithmName = "AES_128/CBC/NoPadding"; |
| 77 | break; |
| 78 | case SaProposal.PSEUDORANDOM_FUNCTION_SHA2_256: |
| 79 | keyLength = 32; |
| 80 | algorithmName = "HmacSHA256"; |
| 81 | break; |
| 82 | case SaProposal.PSEUDORANDOM_FUNCTION_SHA2_384: |
| 83 | keyLength = 48; |
| 84 | algorithmName = "HmacSHA384"; |
| 85 | break; |
| 86 | case SaProposal.PSEUDORANDOM_FUNCTION_SHA2_512: |
| 87 | keyLength = 64; |
| 88 | algorithmName = "HmacSHA512"; |
| 89 | break; |
| 90 | default: |
| 91 | throw new IllegalArgumentException("Unrecognized PRF ID: " + algorithmId); |
| 92 | } |
| 93 | |
| 94 | return new IkeMacPrf(algorithmId, keyLength, algorithmName, isEncryptAlgo); |
| 95 | } |
| 96 | |
| 97 | /** |
| 98 | * Generates SKEYSEED based on the nonces and shared DH secret. |
| 99 | * |
| 100 | * @param nonceInit the IKE initiator nonce. |
| 101 | * @param nonceResp the IKE responder nonce. |
| 102 | * @param sharedDhKey the DH shared key. |
| 103 | * @return the byte array of SKEYSEED. |
| 104 | */ |
| 105 | public byte[] generateSKeySeed(byte[] nonceInit, byte[] nonceResp, byte[] sharedDhKey) { |
| 106 | ByteBuffer keyBuffer = null; |
| 107 | if (getAlgorithmId() == SaProposal.PSEUDORANDOM_FUNCTION_AES128_XCBC) { |
| 108 | keyBuffer = ByteBuffer.allocate(PSEUDORANDOM_FUNCTION_AES128_XCBC_KEY_LEN); |
| 109 | // Use 8 bytes each from initiator and responder nonces as per RFC 7296 |
| 110 | keyBuffer |
| 111 | .put(Arrays.copyOfRange(nonceInit, 0, 8)) |
| 112 | .put(Arrays.copyOfRange(nonceResp, 0, 8)); |
| 113 | } else { |
| 114 | keyBuffer = ByteBuffer.allocate(nonceInit.length + nonceResp.length); |
| 115 | keyBuffer.put(nonceInit).put(nonceResp); |
| 116 | } |
| 117 | |
| 118 | return signBytes(keyBuffer.array(), sharedDhKey); |
| 119 | } |
| 120 | |
| 121 | /** |
| 122 | * Generates a rekey SKEYSEED based on the nonces and shared DH secret. |
| 123 | * |
| 124 | * @param skD the secret for deriving new keys |
| 125 | * @param nonceInit the IKE initiator nonce. |
| 126 | * @param nonceResp the IKE responder nonce. |
| 127 | * @param sharedDhKey the DH shared key. |
| 128 | * @return the byte array of SKEYSEED. |
| 129 | */ |
| 130 | public byte[] generateRekeyedSKeySeed( |
| 131 | byte[] skD, byte[] nonceInit, byte[] nonceResp, byte[] sharedDhKey) { |
| 132 | ByteBuffer dataToSign = null; |
| 133 | if (getAlgorithmId() == SaProposal.PSEUDORANDOM_FUNCTION_AES128_XCBC) { |
| 134 | dataToSign = |
| 135 | ByteBuffer.allocate( |
| 136 | sharedDhKey.length + PSEUDORANDOM_FUNCTION_AES128_XCBC_KEY_LEN); |
| 137 | // Use 8 bytes each from initiator and responder nonces as per RFC 7296 |
| 138 | dataToSign |
| 139 | .put(sharedDhKey) |
| 140 | .put(Arrays.copyOfRange(nonceInit, 0, 8)) |
| 141 | .put(Arrays.copyOfRange(nonceResp, 0, 8)); |
| 142 | } else { |
| 143 | dataToSign = |
| 144 | ByteBuffer.allocate(sharedDhKey.length + nonceInit.length + nonceResp.length); |
| 145 | dataToSign.put(sharedDhKey).put(nonceInit).put(nonceResp); |
| 146 | } |
| 147 | |
| 148 | return signBytes(skD, dataToSign.array()); |
| 149 | } |
| 150 | |
| 151 | /** |
| 152 | * Derives keying materials from IKE/Child SA negotiation. |
| 153 | * |
| 154 | * <p>prf+(K, S) outputs a pseudorandom stream by using negotiated PRF iteratively. In this way |
| 155 | * it can generate long enough keying material containing all the keys for this IKE/Child SA. |
| 156 | * |
| 157 | * @see <a href="https://tools.ietf.org/html/rfc7296#section-2.13">RFC 7296 Internet Key |
| 158 | * Exchange Protocol Version 2 (IKEv2) 2.13. Generating Keying Material </a> |
| 159 | * @param keyBytes the key to sign data. SKEYSEED is used for generating KEYMAT for IKE SA. SK_d |
| 160 | * is used for generating KEYMAT for Child SA. |
| 161 | * @param dataToSign the data to be signed. |
| 162 | * @param keyMaterialLen the length of keying materials. |
| 163 | * @return the byte array of keying materials |
| 164 | */ |
| 165 | public byte[] generateKeyMat(byte[] keyBytes, byte[] dataToSign, int keyMaterialLen) { |
| 166 | return KeyGenerationUtils.prfPlus(this, keyBytes, dataToSign, keyMaterialLen); |
| 167 | } |
| 168 | |
| 169 | /** |
| 170 | * Returns algorithm type as a String. |
| 171 | * |
| 172 | * @return the algorithm type as a String. |
| 173 | */ |
| 174 | @Override |
| 175 | public String getTypeString() { |
| 176 | return "Pseudorandom Function"; |
| 177 | } |
| 178 | } |