来自android，java上的PEM文件的PublicKey [英] PublicKey from PEM file on android, java

问题描述

基本上我正在尝试验证使用openssl的签名如下：

Basically I'm trying to verify signature which using openssl looks like this:

openssl dgst -sha256 -verify prime192v1-pub-v1.pem -signature signatureFile.bin < dataFile.bin

...为了在android上执行此操作，我需要创建 PublicKey 对象。我正在使用的方法抛出 java.security.spec.InvalidKeySpecException：意外的密钥类型在行 kf.generatePublic（new X509EncodedKeySpec（encoded）） 。

... and in order to do that on android I need to create PublicKey object. The method that I'm using throws java.security.spec.InvalidKeySpecException: Unexpected key type at line kf.generatePublic(new X509EncodedKeySpec(encoded)).

import org.spongycastle.util.encoders.Base64;

import java.io.IOException;
import java.security.GeneralSecurityException;
import java.security.KeyFactory;
import java.security.PublicKey;
import java.security.spec.X509EncodedKeySpec;

public class SO {

    public static PublicKey getPublicKeyFromString(String key) throws IOException, GeneralSecurityException {
        String publicKeyPEM = key;
        publicKeyPEM = publicKeyPEM.replace("-----BEGIN PUBLIC KEY-----\n", "");
        publicKeyPEM = publicKeyPEM.replace("-----END PUBLIC KEY-----", "");
        byte[] encoded = Base64.decode(publicKeyPEM);
        KeyFactory kf = KeyFactory.getInstance("RSA");
        return kf.generatePublic(new X509EncodedKeySpec(encoded));
    }

}

这就是我调用方法的方法：

This is how I call the method:

    SO.getPublicKeyFromString(
            "-----BEGIN PUBLIC KEY-----\n" +
            "MEkwEwYHKoZIzj0CAQYIKoZIzj0DAQEDMgAEXMHnQfWiM4oCaLfx296llgz7iaVv\n" +
            "avMPppkzVNZAxtlNLhFlXnNWD0Mw9yzP8/Go\n" +
            "-----END PUBLIC KEY-----"
    );

任何人都知道我做错了什么？

Anyone knows what I'm doing wrong?

推荐答案

我搞定了。公钥是椭圆曲线（p192）公钥，应加载不同。拥有 PublicKey 我能够像使用openssl命令一样验证签名。

I got it working. The public key is elliptic curve (p192) public key and it should be loaded differently. Having PublicKey I was able to verify signature the same way as using openssl command.

import org.bouncycastle.jce.provider.BouncyCastleProvider;

import java.io.Reader;
import java.io.StringReader;
import java.security.KeyFactory;
import java.security.PublicKey;
import java.security.Security;
import java.security.Signature;
import java.security.spec.X509EncodedKeySpec;

public class SO {

    public PublicKey getPublicKey() throws Exception {
        Security.addProvider(new BouncyCastleProvider());
        Reader rdr = new StringReader(
                "-----BEGIN PUBLIC KEY-----\n" +
                        "MEkwEwYHKoZIzj0CAQYIKoZIzj0DAQEDMgAEXMHnQfWiM4oCaLfx296llgz7iaVv\n" +
                        "avMPppkzVNZAxtlNLhFlXnNWD0Mw9yzP8/Go\n" +
                        "-----END PUBLIC KEY-----\n"
        ); // or from file etc.

        org.bouncycastle.util.io.pem.PemObject spki = new org.bouncycastle.util.io.pem.PemReader(rdr).readPemObject();
        PublicKey key = KeyFactory.getInstance("EC", "BC").generatePublic(new X509EncodedKeySpec(spki.getContent()));
        return key;
    }

    public static boolean verify(byte[] data, byte[] signatureBytes, PublicKey publicKey) throws Exception {
        Signature signature = Signature.getInstance("SHA256withECDSA", "BC");
        signature.initVerify(publicKey);
        signature.update(data);
        return signature.verify(signatureBytes);
    }

}

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