解码南非 za-drivers-license

Question

参考这个讨论：Decode South African (ZA) Drivers License

请协助我在 android 上尝试在 Java 中创建 PublicKey 实例时似乎遇到了错误。我在下面粘贴了错误：

java.lang.RuntimeException: error:0D0680A8:asn1 encoding routines:ASN1_CHECK_TLEN:wrong tag

这是代码片段：

Cipher asymmetricCipher = null;
asymmetricCipher = Cipher.getInstance("RSA");
X509EncodedKeySpec publicKeySpec128 = new X509EncodedKeySpec(key128block);
X509EncodedKeySpec publicKeySpec74 = new X509EncodedKeySpec(key74block);

KeyFactory keyFactory = KeyFactory.getInstance("RSA");
Key key = keyFactory.generatePublic(publicKeySpec128);
asymmetricCipher.init(Cipher.DECRYPT_MODE, key);

byte[] plainText = asymmetricCipher.doFinal(topBlocksData[0]);

Answer 1

您尝试读取的编码 public 密钥不是 X509EncodedKeySpec. Instead they are of an even simpler form which, unfortunately, is not supported by Java. However, you can use the Bouncycastle or Spongycastle library to code up a small java routine to parse the values. The code below is copied from to 预期的格式。

import java.io.IOException;
import java.math.BigInteger;
import org.bouncycastle.asn1.ASN1EncodableVector;
import org.bouncycastle.asn1.ASN1InputStream;
import org.bouncycastle.asn1.ASN1Integer;
import org.bouncycastle.asn1.DERSequence;
import org.bouncycastle.asn1.DLSequence;

public class RsaAsn1Example {
// ...
    public static BigInteger [] parseASN1RsaPublicKey(byte [] encoded) throws IOException {
        ASN1InputStream asn1_is = new ASN1InputStream(encoded);
        DLSequence dlSeq = (DLSequence) asn1_is.readObject();
        ASN1Integer asn1_n = (ASN1Integer) dlSeq.getObjectAt(0);
        ASN1Integer asn1_e = (ASN1Integer) dlSeq.getObjectAt(1);
        asn1_is.close();
        return new BigInteger[]{ asn1_n.getPositiveValue(), asn1_e.getPositiveValue()};
    }
// ....
}

可以将 parseASN1RsaPublicKey 返回的值提供给 RsaPublicKeySpec 构造函数以创建 public 键。

同时检查相同的问题以获得替代方案。

解码南非 za-drivers-license

decode south african za-drivers-license

java

android

encryption

rsa

public-key