ios - SecItemCopyMatching 返回 nil 值没有任何错误

Question

我正在尝试使用 CryptoExercise 的 SecKeyWrapper addPeerPublicKey:keyBits: 方法将 RSA 公钥添加到我的 iPhone 钥匙串(keychain)。此方法的逻辑是它首先尝试将 key 添加到钥匙串(keychain)，如果它已经存在 (sanityCheck==errSecDuplicateItem) 它尝试通过调用 SecKeyItemCopyMatching 从钥匙串(keychain)中检索此 key ()。

这正是我的情况: key 已经在钥匙串(keychain)中，因此对 SecKeyItemAdd() 的调用返回 errSecDuplicateItem。

然后它尝试检索现有 key ，但 SecKeyItemCopyMatching() 返回 0(表示没有错误)，但第二个参数 (peerKeyRef) 仍然绝望地为 nil。

这怎么可能？这有什么问题吗？

这里是 CryptoExercise 示例中 [SecKeyWrapper addPeerPublicKey:keyBits:] 的代码以供引用:

- (SecKeyRef)addPeerPublicKey:(NSString *)peerName keyBits:(NSData *)publicKey {
    OSStatus sanityCheck = noErr;
    SecKeyRef peerKeyRef = NULL;
    CFTypeRef persistPeer = NULL;

    LOGGING_FACILITY( peerName != nil, @"Peer name parameter is nil." );
    LOGGING_FACILITY( publicKey != nil, @"Public key parameter is nil." );

    NSData *peerTag = [[NSData alloc] initWithBytes:(const void *) [peerName UTF8String] length:[peerName length]];
    NSMutableDictionary *peerPublicKeyAttr = [[NSMutableDictionary alloc] init];

    [peerPublicKeyAttr setObject:(__bridge id) kSecClassKey forKey:(__bridge id) kSecClass];
    [peerPublicKeyAttr setObject:(__bridge id) kSecAttrKeyTypeRSA forKey:(__bridge id) kSecAttrKeyType];
    [peerPublicKeyAttr setObject:peerTag forKey:(__bridge id) kSecAttrApplicationTag];
    [peerPublicKeyAttr setObject:publicKey forKey:(__bridge id) kSecValueData];
    [peerPublicKeyAttr setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id) kSecReturnPersistentRef];

    sanityCheck = SecItemAdd((__bridge CFDictionaryRef) peerPublicKeyAttr, (CFTypeRef *) &persistPeer);

    // The nice thing about persistent references is that you can write their value out to disk and
    // then use them later. I don't do that here but it certainly can make sense for other situations
    // where you don't want to have to keep building up dictionaries of attributes to get a reference.
    //
    // Also take a look at SecKeyWrapper's methods (CFTypeRef)getPersistentKeyRefWithKeyRef:(SecKeyRef)key
    // & (SecKeyRef)getKeyRefWithPersistentKeyRef:(CFTypeRef)persistentRef.

    LOGGING_FACILITY1( sanityCheck == noErr || sanityCheck == errSecDuplicateItem, @"Problem adding the peer public key to the keychain, OSStatus == %ld.", sanityCheck );

    if (persistPeer) {
        peerKeyRef = [self getKeyRefWithPersistentKeyRef:persistPeer];
    } else {
        [peerPublicKeyAttr removeObjectForKey:(__bridge id) kSecValueData];
        [peerPublicKeyAttr setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id) kSecReturnRef];
        // Let's retry a different way.
        sanityCheck = SecItemCopyMatching((__bridge CFDictionaryRef) peerPublicKeyAttr, (CFTypeRef *) &peerKeyRef);
    }

    LOGGING_FACILITY1( sanityCheck == noErr && peerKeyRef != NULL, @"Problem acquiring reference to the public key, OSStatus == %ld.", sanityCheck );

    if (persistPeer) CFRelease(persistPeer);
    return peerKeyRef;
}

Answer 1

我遇到了同样的问题，我假设您尝试导入不是从其他 iOS 设备导出的 RSA key 。

原因似乎是不兼容的 key 格式——详细来说，iOS 期望某些 ASN1 header 不被设置。为什么函数返回 OK 对我来说只能用错误来解释......

查看 http://blog.flirble.org/2011/01/05/rsa-public-key-openssl-ios/ 处的代码这是正确的解决方案并且对我有用 - 感谢 Chris Luke