ios - 从 iOS 中的 kSecAttrApplicationTag 中提取模数

Question

我正在尝试从 kSecAttrApplicationTag(我从 URL 获取公钥信息)中提取模数。我想比较来自服务器和手动输入的公钥。如果两者相同，那么我们将允许用户继续。否则，它将取消用户的请求。这是一段代码:

SecTrustRef trust = [protectionSpace serverTrust];
SecKeyRef publicKey = SecTrustCopyPublicKey(trust); // here i'm getting complete SecKeyRef info
NSMutableDictionary * queryPublicKey = [[NSMutableDictionary alloc] init];
[queryPublicKey setObject:(__bridge id)publicKey forKey:(__bridge id)kSecAttrApplicationTag];

我也尝试使用 kSecAttrApplicationTag 和 publickey 获取模数，但没有成功。

kSecAttrApplicationTag 键的输出是:

{
atag = "<SecKeyRef algorithm id: 1, key type: RSAPublicKey, version: 2, block size: 2048 bits, exponent: {hex: 10001, decimal: 65537}, modulus: 98A8819BAEA1361029F78D1FA35B4A39A9C6D017501BD56C8D656CAC0800DE90BCF93D465CC7CAFB697841B3DCF47CE4F35E00CC3CC163, addr: 0xa065400>";}

publicKey 的输出与 kSecAttrApplicationTag 相同，但没有 {atag =}(它包含其余内容)。

有人可以帮我解决如何提取模数的问题吗？

Answer 1

看起来 atag 是 XML，所以有几种方法。

1. 使用 XML 解析器:NSXMLParser。
2. 使用正则表达式:NSString 方法 rangeOfString:options: 和选项 NSRegularExpressionSearch。
3. 使用 NSScanner。

使用正则表达式:

NSString *atag = @"<SecKeyRef algorithm id: 1, key type: RSAPublicKey, version: 2, block size: 2048 bits, exponent: {hex: 10001, decimal: 65537}, modulus: 98A8819BAEA1361029F78D1FA35B4A39A9C6D017501BD56C8D656CAC0800DE90BCF93D465CC7CAFB697841B3DCF47CE4F35E00CC3CC163, addr: 0xa065400>";

    NSRange range;

    NSString *blockSizeRegex = @"(?<=block size:\\s?)[0-9]+";
    range = [atag rangeOfString:blockSizeRegex options:NSRegularExpressionSearch];
    if (range.location != NSNotFound) {
        NSString *blockSize = [atag substringWithRange:range];
        NSLog(@"blockSize: %@", blockSize);
    }

    NSString *modulusRegex = @"(?<=modulus:\\s?)[0-9A-Z]+";
    range = [atag rangeOfString:modulusRegex options:NSRegularExpressionSearch];
    if (range.location != NSNotFound) {
        NSString *modulus = [atag substringWithRange:range];
        NSLog(@"modulus: %@", modulus);
    }

    NSString *exponentRegex = @"(?<=decimal:\\s?)[0-9]+";
    range = [atag rangeOfString:exponentRegex options:NSRegularExpressionSearch];
    if (range.location != NSNotFound) {
        NSString *exponent = [atag substringWithRange:range];
        NSLog(@"exponent: %@", exponent);
    }

输出:

blockSize: 2048
modulus: 98A8819BAEA1361029F78D1FA35B4A39A9C6D017501BD56C8D656CAC0800DE90BCF93D465CC7CAFB697841B3DCF47CE4F35E00CC3CC163
exponent: 65537

ICU 用户指南 Regular Expressions