Java 从文件加载RSA公钥

下面是从相关信息的链接，其扎基提供。

生成2048位RSA私钥

$ openssl genrsa -out private_key.pem 2048

将私钥转换为PKCS＃8格式（以便Java可以读取）

$ openssl pkcs8 -topk8 -inform PEM -outform DER -in private_key.pem -out private_key.der -nocrypt

以DER格式输出公共密钥部分（以便Java可以读取）

$ openssl rsa -in private_key.pem -pubout -outform DER -out public_key.der

Private key

import java.io.*;import java.nio.*;import java.security.*;import java.security.spec.*;public class PrivateKeyReader {  public static PrivateKey get(String filename)  throws Exception {    byte[] keyBytes = Files.readAllBytes(Paths.get(filename));    PKCS8EnpredKeySpec spec =      new PKCS8EnpredKeySpec(keyBytes);    KeyFactory kf = KeyFactory.getInstance("RSA");    return kf.generatePrivate(spec);  }}

Public key

import java.io.*;import java.nio.*;import java.security.*;import java.security.spec.*;public class PublicKeyReader {  public static PublicKey get(String filename)    throws Exception {    byte[] keyBytes = Files.readAllBytes(Paths.get(filename));    X509EnpredKeySpec spec =      new X509EnpredKeySpec(keyBytes);    KeyFactory kf = KeyFactory.getInstance("RSA");    return kf.generatePublic(spec);  }}