Android：InvalidKeySpecException：編碼密鑰規格不被識別

Question

當我嘗試從字符串中生成RSA公鑰時。我在下面提到異常。我試圖在Android中驗證生成的鍵（字符串，使用Swift）。如何將字符串轉換爲私鑰/公鑰？

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; 
} 

異常

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) 

在IOS公共密鑰：

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

Answer 1

不幸的是，你所擁有的是編碼PKCS#1 RSAPublicKey 64基，這是一件好事Java不生產或消費。 Java產生並消費了一個稍微更通用，更復雜的X.509 SubjectPublicKeyInfo。

使用Bouncycastle庫，這裏是一些示例代碼，以產生一個RSAPublicKey：

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())); 
    } 
}