android用.der公钥验证文件的签名

时间：2012-12-10 18:52:01

标签： android openssl rsa digital-signature sha1

我正在尝试验证文件的签名。我按照这些说明生成证书：

// generate a private key with size of 2048 bits
openssl genrsa -out private_key.pem 2048

// derive a public key from the above private key
openssl rsa -in private_key.pem -out public_key.pem -outform PEM -pubout

// iOS will not import PEM encoded data so it needs to be converted to DER encoded data
openssl rsa -pubin -inform PEM -outform DER -in public_key.pem -out public_key.der

// generate a self-signed certificate for testing
openssl req -new -x509 -key private_key.pem -out test_cert.pem -days 1095

// show the content of the original certificate
openssl x509 -in test_cert.pem -text -noout
// convert the certificate to DER format
openssl x509 -in test_cert.pem -outform der -out test_cert.der
// show the content of the new certificate
openssl x509 -in test_cert.der -inform der -text -noout

我使用this link处的示例来散列一些数据并验证一切都很好（我做了第2 - 5步）。

现在我正在尝试将.der文件，签名文件和数据文件放入Android应用程序中，并且基本上再次验证它是好的。我没有收到任何错误，但我没有得到错误。以下是我写的代码：

import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.util.Base64;
import android.util.Log;
import android.widget.TextView;

import java.io.*;
import java.security.*;
import java.security.cert.CertificateFactory;
import java.security.cert.Certificate;

// Most of the below is taken from:
// http://www.herongyang.com/JDK/Digital-Signature-JcaVerify-Signature-Verification-Program.html
public class MyActivity extends Activity {

String input = Environment.getExternalStorageDirectory() + "/data.txt";
String signFile = Environment.getExternalStorageDirectory() + "/signature";
String signAlgo = "SHA1withRSA";
int keyFile = R.raw.test_cert_josh;
String TAG = "VERIFY";

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    TextView textView = (TextView) findViewById(R.id.textView);

    try {
        PublicKey pubKey = readPublicKey(keyFile);
        byte[] sign = readSignature(signFile);
        textView.setText(verify(input, signAlgo, sign, pubKey) + "");
    } catch (Exception e) {
        e.printStackTrace();
    }
}

PublicKey readPublicKey(int cert_id) throws Exception {
    InputStream in = MyActivity.this.getResources().openRawResource(cert_id);
    byte[] buff = new byte[4000];
    int bytesRead;
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    while((bytesRead = in.read(buff)) != -1) {
        out.write(buff, 0, bytesRead);
        Log.i(TAG, "bytes read: " + bytesRead);
    }

    byte[] publicKeyBytes = out.toByteArray();

    CertificateFactory cf = CertificateFactory.getInstance("X509");
    Certificate cert = cf.generateCertificate(new ByteArrayInputStream(publicKeyBytes));

    PublicKey pubKey = cert.getPublicKey();
    Log.i(TAG, "Public Key Info: ");
    Log.i(TAG, "Algorithm = " + pubKey.getAlgorithm());
    Log.i(TAG, "toString = " + pubKey.toString());
    return pubKey;
}

byte[] readSignature(String input) throws Exception {
    FileInputStream signStream = new FileInputStream(input);
    byte[] signBytes = new byte[signStream.available()];
    signStream.read(signBytes);
    signStream.close();
    return  signBytes;
}

boolean verify(String input, String algorithm, byte[] sign, PublicKey pubKey) throws Exception {
    Signature sg = Signature.getInstance(algorithm);
    sg.initVerify(pubKey);
    Log.i(TAG, "Signature Object Info: ");
    Log.i(TAG, "Algorithm = "+sg.getAlgorithm());
    Log.i(TAG, "Provider = "+sg.getProvider());

    FileInputStream in = new FileInputStream(input);
    byte[] buff = new byte[in.available()];
    in.read(buff);

    sg.update(buff);

    boolean ok = sg.verify(sign);
    Log.i(TAG, "Verify Processing Info: ");
    Log.i(TAG, "Verification result = "+ok);
    return ok;
}
}

我读过的所有内容都说我的代码是正确的。我认为关于获取公钥的部分是正确的，因为模数与实际.der文件中的模数匹配。

请帮忙！

修改 我认为它与我如何阅读签名文件或数据文件有关。我很确定我正确地获取了有关公钥的所有信息，因为我打印出有关它的其他信息，它与之匹配openssl输出

修改 根据Nikolay的建议，我尝试使用此代码在openssl中签署Android应用程序内的相同数据：

// testing code to sign it myself
// read the data file in
FileInputStream dataStream = new FileInputStream(input);
byte[] dataBytes = new byte[dataStream.available()];
dataStream.read(dataBytes);
dataStream.close();

// hash the data file, like i do with openssl
// per Nikolay's comments, this is not needed
MessageDigest digest = MessageDigest.getInstance("SHA-1");
// digest.update(dataBytes, 0, dataBytes.length);
// dataBytes = digest.digest();
Log.i(TAG, "data from file: " + new String(dataBytes));

// read the private key in
FileInputStream fis = new FileInputStream(Environment.getExternalStorageDirectory() + "/phaero/private_key.pem");
byte[] keyBytes = new byte[fis.available()];
fis.read(keyBytes);
fis.close();

// clean up the private key and decode it
String temp = new String(keyBytes);
Log.i(TAG, "private key: " + temp);
String privKeyPEM = temp.replace("-----BEGIN RSA PRIVATE KEY-----\n", "");
privKeyPEM = privKeyPEM.replace("-----END RSA PRIVATE KEY-----", "");
byte[] decoded = Base64.decode(privKeyPEM.getBytes(), Base64.DEFAULT);

// create the private key object from the private key data
PKCS8EncodedKeySpec private_spec = new PKCS8EncodedKeySpec(decoded);
KeyFactory kf = KeyFactory.getInstance("RSA");
PrivateKey privateKey =  kf.generatePrivate(private_spec);

// set up for signing
Signature signer = Signature.getInstance(signAlgo);
signer.initSign(privateKey);
signer.update(dataBytes, 0, dataBytes.length);

// sign, and hash again so i can compare against openssl output
byte[] signed = signer.sign();
digest.update(signed, 0, signed.length);
Log.i(TAG, new BigInteger(1, digest.digest()).toString(16));

快速注意：在Jelly Bean中使用上面的代码，你必须在创建KeyFactory时指定“BC”。

然后我散列签名结果，看看它是否与openssl生成的签名文件的哈希匹配，并且它们不匹配..所以我不知道这意味着什么，但我知道这意味着什么！我假设我需要在openssl中创建签名文件时指定某种附加选项？

修改

根据Nikolay在下面的评论，我更新了我的测试代码以不签名，但是在java中创建的签名的哈希仍然与使用openssl创建的签名文件的哈希不匹配...不确定什么是错的，Java，OpenSSL，还是我。

1 个答案:

答案 0 :(得分：3)

在@NikolayElenkov的大量帮助之后，我终于弄清楚出了什么问题。尝试不同的谷歌搜索，我偶然发现this stackoverflow question，那家伙说你可以运行两个不同的签名命令。当我创建所有签名时，我正在使用上面链接的内容：

// create a hash
echo 'data to sign' > data.txt
openssl dgst -sha1 < data.txt > hash
// sign it
openssl rsautl -sign -inkey private.pem -keyform PEM -in hash  > signature
// verify it
openssl rsautl -verify -inkey public.pem -keyform PEM -pubin -in signature > verified
diff -s verified hash

从我今天发现的帖子中，我试过了：

openssl dgst -sha1 -sign privateKey.pem -out signature1 someInputFile
正如那家伙所说，

创建了一个不同的签名文件。这是我的Android代码所需要的！所以，得到这个验证的答案是我需要改变我生成签名文件的方式！ （如果没有@NikolayElenkov，我不会有这么远，非常感谢！）

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