iOS，rsa加密随机发生失败

+ (SecKeyRef)addPublicKey:(NSString *)key{
    NSRange spos = [key rangeOfString:@"-----BEGIN PUBLIC KEY-----"];
    NSRange epos = [key rangeOfString:@"-----END PUBLIC KEY-----"];
    if(spos.location != NSNotFound && epos.location != NSNotFound){
        NSUInteger s = spos.location + spos.length;
        NSUInteger e = epos.location;
        NSRange range = NSMakeRange(s, e-s);
        key = [key substringWithRange:range];
    }
    key = [key stringByReplacingOccurrencesOfString:@"\r" withString:@""];
    key = [key stringByReplacingOccurrencesOfString:@"\n" withString:@""];
    key = [key stringByReplacingOccurrencesOfString:@"\t" withString:@""];
    key = [key stringByReplacingOccurrencesOfString:@" "  withString:@""];
    
    NSData *data = [RSA hexStrToNSData:key];
    data = [RSA stripPublicKeyHeader:data];
    if(!data){
        return nil;
    }
    
    NSString *tag = @"what_the_fuck_is_this";
    NSData *d_tag = [NSData dataWithBytes:[tag UTF8String] length:[tag length]];
    
    // Delete any old lingering key with the same tag
    NSMutableDictionary *publicKey = [[NSMutableDictionary alloc] init];
    [publicKey setObject:(__bridge id) kSecClassKey forKey:(__bridge id)kSecClass];
    [publicKey setObject:(__bridge id) kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];
    [publicKey setObject:d_tag forKey:(__bridge id)kSecAttrApplicationTag];
    SecItemDelete((__bridge CFDictionaryRef)publicKey);
    
    // Add persistent version of the key to system keychain
    [publicKey setObject:data forKey:(__bridge id)kSecValueData];
    [publicKey setObject:(__bridge id) kSecAttrKeyClassPublic forKey:(__bridge id)
     kSecAttrKeyClass];
    [publicKey setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)
     kSecReturnPersistentRef];
    
    CFTypeRef persistKey = nil;
    OSStatus status = SecItemAdd((__bridge CFDictionaryRef)publicKey, &persistKey);
    if (persistKey != nil){
        CFRelease(persistKey);
    }
    if ((status != noErr) && (status != errSecDuplicateItem)) {
        return nil;
    }
    
    [publicKey removeObjectForKey:(__bridge id)kSecValueData];
    [publicKey removeObjectForKey:(__bridge id)kSecReturnPersistentRef];
    [publicKey setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)kSecReturnRef];
    [publicKey setObject:(__bridge id) kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];
    
    // Now fetch the SecKeyRef version of the key
    SecKeyRef keyRef = nil;
    status = SecItemCopyMatching((__bridge CFDictionaryRef)publicKey, (CFTypeRef *)&keyRef);
    if(status != noErr){
        return nil;
    }
    return keyRef;
}

这里的keyRef有的时候会是nil,有知道知道问题在哪么？
当keyRef变成nil的时候，key是值得，

---

我也遇到这种情况，status=0，苹果文档提到是返回成功的，但是keyRef是nil

---

好像看到过这问题，有可能是 public key 的问题。可以试试在前面插一个0…… 参考这里