我用以下方法生成了一个私钥:
openssl genrsa [-out file] –des3
在此之后,我使用以下命令生成了一个公钥:
openssl rsa –pubout -in private.key [-out file]
我想使用我的私钥对某些消息签名,并使用如下代码对我的公钥验证其他消息:
public String sign(String message) throws SignatureException{
try {
Signature sign = Signature.getInstance("SHA1withRSA");
sign.initSign(privateKey);
sign.update(message.getBytes("UTF-8"));
return new String(Base64.encodeBase64(sign.sign()),"UTF-8");
} catch (Exception ex) {
throw new SignatureException(ex);
}
}
public boolean verify(String message, String signature) throws SignatureException{
try {
Signature sign = Signature.getInstance("SHA1withRSA");
sign.initVerify(publicKey);
sign.update(message.getBytes("UTF-8"));
return sign.verify(Base64.decodeBase64(signature.getBytes("UTF-8")));
} catch (Exception ex) {
throw new SignatureException(ex);
}
}
我找到了一种解决方案,可以将我的私钥转换为PKCS8格式并加载它。它可以与以下代码一起工作:
public PrivateKey getPrivateKey(String filename) throws Exception {
File f = new File(filename);
FileInputStream fis = new FileInputStream(f);
DataInputStream dis = new DataInputStream(fis);
byte[] keyBytes = new byte[(int) f.length()];
dis.readFully(keyBytes);
dis.close();
PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(keyBytes);
KeyFactory kf =
KeyFactory.getInstance("RSA");
return kf.generatePrivate(spec);
}
最后,我的问题是:如何从文件加载RSA公钥?
我认为也许我需要将我的公共密钥文件转换为x509格式,然后使用X509EncodedKeySpec
。但是我该怎么办呢?
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
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));
PKCS8EncodedKeySpec spec =
new PKCS8EncodedKeySpec(keyBytes);
KeyFactory kf = KeyFactory.getInstance("RSA");
return kf.generatePrivate(spec);
}
}
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));
X509EncodedKeySpec spec =
new X509EncodedKeySpec(keyBytes);
KeyFactory kf = KeyFactory.getInstance("RSA");
return kf.generatePublic(spec);
}
}
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