如果您使用的是BouncyCastle，请尝试以下操作：
import java.io.File;import java.io.FileReader;import java.io.IOException;import java.security.KeyPair;import java.security.Security;import java.security.Signature;import java.util.Arrays;import org.bouncycastle.jce.provider.BouncyCastleProvider;import org.bouncycastle.openssl.PEMReader;import org.bouncycastle.openssl.PasswordFinder;import org.bouncycastle.util.enprers.Hex;public class SignatureExample { public static void main(String [] args) throws Exception { Security.addProvider(new BouncyCastleProvider()); String message = "hello world"; File privateKey = new File("private.pem"); KeyPair keyPair = readKeyPair(privateKey, "password".toCharArray()); Signature signature = Signature.getInstance("SHA256WithRSAEncryption"); signature.initSign(keyPair.getPrivate()); signature.update(message.getBytes()); byte [] signatureBytes = signature.sign(); System.out.println(new String(Hex.enpre(signatureBytes))); Signature verifier = Signature.getInstance("SHA256WithRSAEncryption"); verifier.initVerify(keyPair.getPublic()); verifier.update(message.getBytes()); if (verifier.verify(signatureBytes)) { System.out.println("Signature is valid"); } else { System.out.println("Signature is invalid"); } } private static KeyPair readKeyPair(File privateKey, char [] keyPassword) throws IOException { FileReader fileReader = new FileReader(privateKey); PEMReader r = new PEMReader(fileReader, new DefaultPasswordFinder(keyPassword)); try { return (KeyPair) r.readObject(); } catch (IOException ex) { throw new IOException("The private key could not be decrypted", ex); } finally { r.close(); fileReader.close(); } } private static class DefaultPasswordFinder implements PasswordFinder { private final char [] password; private DefaultPasswordFinder(char [] password) { this.password = password; } @Override public char[] getPassword() { return Arrays.copyOf(password, password.length); } } }
