从模数和指数生成 RSA Public 密钥

Question

我正在寻找从 Objective-C 中的模数和指数生成一个 rsa public 密钥 (pem)。此功能可以在 Java 中通过以下方式完成；

PublicKey publicKey = KeyFactory.getInstance("RSA").generatePublic(new RSAPublicKeySpec(modulus, exponent));

尽管我在为 iOS 平台编写此代码时遇到了一些问题。我知道 OpenSSL, but I couldn't find a successful method and am still unable to generate this key. Also took a look at SCZ-BasicEncodingRules-iOS 但是这个 returns 是一个 NSData 值，我一直在想办法把它转换成 NSString。

Answer 1

如果您想创建 .PEM 格式，您需要对 berData 方法的输出进行 base64 编码。您还需要添加页眉和页脚行。

测试数据和代码，见bytesFromHexString答案末尾：

NSString *modulusString =  @"c19bccae1e67743fab1c978f03122fb1a78ef05d565a2964728062ad0365e4751b8253df5fd13ab4ecb95c81ff17b91f969e4fb3d8274c30533338684278f6e5548027df775c055943a24a4117b0274c296c68b722c71670d4b21489a3da05d37ba06f2fb771b671a2c746bae4a049dc718fba19a75f1fb8ae1dd715b33d66a3";
NSString *exponentString = @"010001";

NSData *pubKeyModData = bytesFromHexString(modulusString);
NSData *pubKeyExpData = bytesFromHexString(exponentString);
NSArray *keyArray = @[pubKeyModData, pubKeyExpData];

//Given that you are using SCZ-BasicEncodingRules-iOS:
NSData *berData = [keyArray berData];
NSLog(@"berData:\n%@", berData);

NSString *berBase64 = [berData base64EncodedStringWithOptions:0];
NSString *preamble = @"-----BEGIN CERTIFICATE REQUEST-----";
NSString *postamble = @"-----END CERTIFICATE REQUEST-----";
NSString *pem = [NSString stringWithFormat:@"%@\n%@\n%@", preamble, berBase64, postamble];
NSLog(@"pem:\n%@", pem);

带有测试数据的输出：

berData:
30818802 8180c19b ccae1e67 743fab1c 978f0312 2fb1a78e f05d565a 29647280 62ad0365 e4751b82 53df5fd1 3ab4ecb9 5c81ff17 b91f969e 4fb3d827 4c305333 38684278 f6e55480 27df775c 055943a2 4a4117b0 274c296c 68b722c7 1670d4b2 1489a3da 05d37ba0 6f2fb771 b671a2c7 46bae4a0 49dc718f ba19a75f 1fb8ae1d d715b33d 66a30203 010001

pem:
-----BEGIN CERTIFICATE REQUEST-----
  MIGIAoGAwZvMrh5ndD+rHJePAxIvsaeO8F1WWilkcoBirQNl5HUbglPfX9E6tOy5XIH/F7kflp5Ps9gnTDBTMzhoQnj25VSAJ993XAVZQ6JKQRewJ0wpbGi3IscWcNSyFImj2gXTe6BvL7dxtnGix0a65KBJ3HGPuhmnXx+4rh3XFbM9ZqMCAwEAAQ==
-----END CERTIFICATE REQUEST-----

将十六进制-ascii 转换为数据：

NSData* bytesFromHexString(NSString * aString) {
    NSString *theString = [[aString componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] componentsJoinedByString:nil];

    NSMutableData* data = [NSMutableData data];
    int idx;
    for (idx = 0; idx+2 <= theString.length; idx+=2) {
        NSRange range = NSMakeRange(idx, 2);
        NSString* hexStr = [theString substringWithRange:range];
        NSScanner* scanner = [NSScanner scannerWithString:hexStr];
        unsigned int intValue;
        if ([scanner scanHexInt:&intValue])
            [data appendBytes:&intValue length:1];
    }
    return data;
}

从模数和指数生成 RSA Public 密钥

Generate RSA Public Key from Modulus and Exponent

openssl

rsa

objective-c

public-key-encryption

ios