Android：InvalidKeySpecException：无法识别编码的密钥规范

Question

当我尝试从字符串生成 RSA 公钥时。我得到下面提到的异常。我正在尝试在 Android 中验证生成的密钥（字符串，使用 Swift）。如何将字符串转换为私钥/公钥？

static PublicKey getRSAPublicKeyFromString (String publicKeyPEM){
    try {
        KeyFactory keyFactory = KeyFactory.getInstance("RSA", "SC");
        byte[] publicKeyBytes = Base64.decode(publicKeyPEM.getBytes("UTF-8"), Base64.DEFAULT);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(publicKeyBytes);
        return keyFactory.generatePublic(x509KeySpec);
    }catch (Exception e){
        e.printStackTrace ();
    }

    return null;
}

例外

java.security.spec.InvalidKeySpecException: encoded key spec not recognised
at org.spongycastle.jcajce.provider.asymmetric.util.BaseKeyFactorySpi.engineGeneratePublic(BaseKeyFactorySpi.java:52)
at org.spongycastle.jcajce.provider.asymmetric.rsa.KeyFactorySpi.engineGeneratePublic(KeyFactorySpi.java:130)
at java.security.KeyFactory.generatePublic(KeyFactory.java:172)

ios 中的公钥：

MIGJAoGBAOibWF15OhLJQAWpQN++UFqyG+2uLEG8PPvCajwwh6FWi6jLiZ9VN+l3JpiJTQwF/yxlSJCZCoYnljKeRBnNxpzBnuTJsyuZ4hI8ehLzDvh9nYzX/TlcZYVshJzyIVRZAbuFOCLNIltjB+Qmw8YGlxzeDSFaB6eEC1OP49hDakURAgMBAAE=

Answer 1

不幸的是，您拥有的是 base64 编码的PKCS#1 RSAPublicKey，这是 Java 不会产生或消耗的东西。 Java 产生并使用了一个更通用、更复杂的X.509 SubjectPublicKeyInfo。

使用Bouncycastle 库，下面是一些生成 RSAPublicKey 的示例代码：

import org.bouncycastle.asn1.ASN1InputStream;
import org.bouncycastle.asn1.ASN1Primitive;

import java.security.KeyFactory;
import java.security.PublicKey;
import java.security.spec.RSAPublicKeySpec;
import java.util.Base64;

public class Main {

    public static void main(String[] args) throws Exception {
        String pubkey64 = "MIGJAoGBAOibWF15OhLJQAWpQN++UFqyG+2uLEG8PPvCajwwh6FWi6jLiZ9VN+l3JpiJTQwF/yxlSJCZCoYnljKeRBnNxpzBnuTJsyuZ4hI8ehLzDvh9nYzX/TlcZYVshJzyIVRZAbuFOCLNIltjB+Qmw8YGlxzeDSFaB6eEC1OP49hDakURAgMBAAE=";
        PublicKey rsaPub = readRSAPublicKey(pubkey64);
        System.out.println(rsaPub);
    }

    private static PublicKey readRSAPublicKey(String pubkey64) throws Exception {
        byte [] derRsaPubBytes = Base64.getDecoder().decode(pubkey64);
        ASN1Primitive asn1Prime = new ASN1InputStream(derRsaPubBytes).readObject();
        org.bouncycastle.asn1.pkcs.RSAPublicKey rsaPub = org.bouncycastle.asn1.pkcs.RSAPublicKey.getInstance(asn1Prime);
        KeyFactory kf = KeyFactory.getInstance("RSA");
        return kf.generatePublic(new RSAPublicKeySpec(rsaPub.getModulus(), rsaPub.getPublicExponent()));
    }
}