keychain/trust/TrustedPeers/TPPeerPermanentInfo.m

   1 /*
   2  * Copyright (c) 2017 Apple Inc. All Rights Reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24 #import "TPPeerPermanentInfo.h"
  25 #import "TPUtils.h"
  26
  27 static const NSString *kMachineID = @"machineID";
  28 static const NSString *kModelID = @"modelID";
  29 static const NSString *kEpoch = @"epoch";
  30 static const NSString *kTrustSigningKey = @"trustSigningKey";
  31
  32
  33 @interface TPPeerPermanentInfo ()
  34
  35 @property (nonatomic, strong) NSString* machineID;
  36 @property (nonatomic, strong) NSString* modelID;
  37 @property (nonatomic, assign) TPCounter epoch;
  38 @property (nonatomic, strong) id<TPSigningKey> trustSigningKey;
  39 @property (nonatomic, strong) NSData *permanentInfoPList;
  40 @property (nonatomic, strong) NSData *permanentInfoSig;
  41 @property (nonatomic, strong) NSString *peerID;
  42
  43 @end
  44
  45
  46 @implementation TPPeerPermanentInfo
  47
  48 + (instancetype)permanentInfoWithMachineID:(NSString *)machineID
  49                                    modelID:(NSString *)modelID
  50                                      epoch:(TPCounter)epoch
  51                            trustSigningKey:(id<TPSigningKey>)trustSigningKey
  52                             peerIDHashAlgo:(TPHashAlgo)peerIDHashAlgo
  53                                      error:(NSError **)error
  54 {
  55     TPPeerPermanentInfo* info = [[TPPeerPermanentInfo alloc] init];
  56     info.machineID = [machineID copy];
  57     info.modelID = [modelID copy];
  58     info.epoch = epoch;
  59     info.trustSigningKey = trustSigningKey;
  60
  61     NSDictionary *dict = @{
  62                            kMachineID: machineID,
  63                            kModelID: modelID,
  64                            kEpoch: @(epoch),
  65                            kTrustSigningKey: [trustSigningKey publicKey]
  66                            };
  67     NSData *data = [TPUtils serializedPListWithDictionary:dict];
  68     NSData *sig = [trustSigningKey signatureForData:data withError:error];
  69     if (nil == sig) {
  70         return nil;
  71     }
  72     info.permanentInfoPList = data;
  73     info.permanentInfoSig = sig;
  74     info.peerID = [TPPeerPermanentInfo peerIDForPermanentInfoPList:data
  75                                                   permanentInfoSig:sig
  76                                                     peerIDHashAlgo:peerIDHashAlgo];
  77     return info;
  78 }
  79
  80 + (NSString *)peerIDForPermanentInfoPList:(NSData *)permanentInfoPList
  81                          permanentInfoSig:(NSData *)permanentInfoSig
  82                            peerIDHashAlgo:(TPHashAlgo)peerIDHashAlgo
  83
  84 {
  85     TPHashBuilder *hasher = [[TPHashBuilder alloc] initWithAlgo:peerIDHashAlgo];
  86     [hasher updateWithData:permanentInfoPList];
  87     [hasher updateWithData:permanentInfoSig];
  88     return [hasher finalHash];
  89 }
  90
  91 + (instancetype)permanentInfoWithPeerID:(NSString *)peerID
  92                      permanentInfoPList:(NSData *)permanentInfoPList
  93                        permanentInfoSig:(NSData *)permanentInfoSig
  94                              keyFactory:(id<TPSigningKeyFactory>)keyFactory
  95 {
  96     id obj = [NSPropertyListSerialization propertyListWithData:permanentInfoPList
  97                                                         options:NSPropertyListImmutable
  98                                                          format:nil
  99                                                           error:NULL];
 100     if (![obj isKindOfClass:[NSDictionary class]]) {
 101         return nil;
 102     }
 103     NSDictionary *dict = obj;
 104
 105     TPPeerPermanentInfo *info = [[TPPeerPermanentInfo alloc] init];
 106     info.peerID = peerID;
 107     info.permanentInfoPList = permanentInfoPList;
 108     info.permanentInfoSig = permanentInfoSig;
 109
 110     if (![dict[kMachineID] isKindOfClass:[NSString class]]) {
 111         return nil;
 112     }
 113     info.machineID = dict[kMachineID];
 114
 115     if (![dict[kModelID] isKindOfClass:[NSString class]]) {
 116         return nil;
 117     }
 118     info.modelID = dict[kModelID];
 119
 120     if (![dict[kEpoch] isKindOfClass:[NSNumber class]]) {
 121         return nil;
 122     }
 123     info.epoch = [dict[kEpoch] unsignedLongLongValue];
 124
 125     if (![dict[kTrustSigningKey] isKindOfClass:[NSData class]]) {
 126         return nil;
 127     }
 128     info.trustSigningKey = [keyFactory keyWithPublicKeyData:dict[kTrustSigningKey]];
 129     if (nil == info.trustSigningKey) {
 130         return nil;
 131     }
 132     if (![info.trustSigningKey checkSignature:permanentInfoSig matchesData:permanentInfoPList]) {
 133         return nil;
 134     }
 135
 136     // check peerID is hash of (permanentInfoPList + permanentInfoSig)
 137     TPHashAlgo algo = [TPHashBuilder algoOfHash:peerID];
 138     if (algo == kTPHashAlgoUnknown) {
 139         return nil;
 140     }
 141     NSString* checkHash = [TPPeerPermanentInfo peerIDForPermanentInfoPList:info.permanentInfoPList
 142                                                   permanentInfoSig:info.permanentInfoSig
 143                                                     peerIDHashAlgo:algo];
 144     if (![checkHash isEqualToString:peerID]) {
 145         return nil;
 146     }
 147
 148     return info;
 149 }
 150
 151 @end