85 lines
3.1 KiB
Objective-C
85 lines
3.1 KiB
Objective-C
/*
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* Copyright 2019 Google
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#import "FIRInstanceIDKeyPairUtilities.h"
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#import <CommonCrypto/CommonDigest.h>
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#import "FIRInstanceIDDefines.h"
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#import "FIRInstanceIDKeyPair.h"
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#import "FIRInstanceIDLogger.h"
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#import "FIRInstanceIDStringEncoding.h"
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NSString *FIRInstanceIDWebSafeBase64(NSData *data) {
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// Websafe encoding with no padding.
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FIRInstanceIDStringEncoding *encoding =
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[FIRInstanceIDStringEncoding rfc4648Base64WebsafeStringEncoding];
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[encoding setDoPad:NO];
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return [encoding encode:data];
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}
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NSData *FIRInstanceIDSHA1(NSData *data) {
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unsigned int outputLength = CC_SHA1_DIGEST_LENGTH;
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unsigned char output[outputLength];
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unsigned int length = (unsigned int)[data length];
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CC_SHA1(data.bytes, length, output);
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return [NSMutableData dataWithBytes:output length:outputLength];
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}
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NSDictionary *FIRInstanceIDKeyPairQuery(NSString *tag, BOOL addReturnAttr, BOOL returnData) {
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NSMutableDictionary *queryKey = [NSMutableDictionary dictionary];
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NSData *tagData = [tag dataUsingEncoding:NSUTF8StringEncoding];
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queryKey[(__bridge id)kSecClass] = (__bridge id)kSecClassKey;
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queryKey[(__bridge id)kSecAttrApplicationTag] = tagData;
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queryKey[(__bridge id)kSecAttrKeyType] = (__bridge id)kSecAttrKeyTypeRSA;
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if (addReturnAttr) {
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if (returnData) {
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queryKey[(__bridge id)kSecReturnData] = @(YES);
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} else {
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queryKey[(__bridge id)kSecReturnRef] = @(YES);
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}
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}
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return queryKey;
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}
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NSString *FIRInstanceIDAppIdentity(FIRInstanceIDKeyPair *keyPair) {
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// An Instance-ID is a 64 bit (8 byte) integer with a fixed 4-bit header of 0111 (=^ 0x7).
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// The variable 60 bits are obtained by truncating the SHA1 of the app-instance's public key.
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SecKeyRef publicKeyRef = [keyPair publicKey];
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if (!publicKeyRef) {
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FIRInstanceIDLoggerError(kFIRInstanceIDMessageCodeKeyPair002,
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@"Unable to create a valid asymmetric crypto key");
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return nil;
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}
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NSData *publicKeyData = keyPair.publicKeyData;
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NSData *publicKeySHA1 = FIRInstanceIDSHA1(publicKeyData);
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const uint8_t *bytes = publicKeySHA1.bytes;
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NSMutableData *identityData = [NSMutableData dataWithData:publicKeySHA1];
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uint8_t b0 = bytes[0];
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// Take the first byte and make the initial four 7 by initially making the initial 4 bits 0
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// and then adding 0x70 to it.
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b0 = 0x70 + (0xF & b0);
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// failsafe should give you back b0 itself
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b0 = (b0 & 0xFF);
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[identityData replaceBytesInRange:NSMakeRange(0, 1) withBytes:&b0];
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NSData *data = [identityData subdataWithRange:NSMakeRange(0, 8 * sizeof(Byte))];
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return FIRInstanceIDWebSafeBase64(data);
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}
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