sm2私钥、公钥转成pem

将SM2私钥、公钥转换为PEM格式，可以按照以下步骤进行：

1. 私钥转换：

import org.bouncycastle.asn1.pkcs.PrivateKeyInfo;
import org.bouncycastle.asn1.x509.AlgorithmIdentifier;
import org.bouncycastle.crypto.params.ECPrivateKeyParameters;
import org.bouncycastle.crypto.util.PrivateKeyInfoFactory;
import org.bouncycastle.crypto.util.PrivateKeyInfoParser;
import org.bouncycastle.crypto.util.PrivateKeyInfoFactory;
import org.bouncycastle.crypto.util.PrivateKeyInfoFactory;
import org.bouncycastle.jcajce.provider.asymmetric.ec.BCECPrivateKey;

import java.io.IOException;
import java.io.StringWriter;
import java.security.PrivateKey;
import java.security.interfaces.ECPrivateKey;
import java.security.spec.PKCS8EncodedKeySpec;

public class SM2Util {

    /**
     * 将SM2私钥转换为PEM格式
     *
     * @param privateKey SM2私钥
     * @return PEM格式的SM2私钥
     * @throws IOException
     */
    public static String privateKeyToPEM(ECPrivateKey privateKey) throws IOException {
        PrivateKeyInfo privateKeyInfo = PrivateKeyInfoFactory.createPrivateKeyInfo(privateKey);
        StringWriter stringWriter = new StringWriter();
        PemWriter pemWriter = new PemWriter(stringWriter);
        pemWriter.writeObject(new PemObject("PRIVATE KEY", privateKeyInfo.getEncoded()));
        pemWriter.close();
        return stringWriter.toString();
    }

    /**
     * 将PEM格式的SM2私钥转换为ECPrivateKey对象
     *
     * @param pem PEM格式的SM2私钥
     * @return ECPrivateKey对象
     * @throws Exception
     */
    public static ECPrivateKey pemToPrivateKey(String pem) throws Exception {
        PemReader pemReader = new PemReader(new StringReader(pem));
        PemObject pemObject = pemReader.readPemObject();
        byte[] derBytes = pemObject.getContent();
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(derBytes);
        KeyFactory keyFactory = KeyFactory.getInstance("EC", new BouncyCastleProvider());
        return (ECPrivateKey) keyFactory.generatePrivate(keySpec);
    }
}

2. 公钥转换：

import org.bouncycastle.asn1.x509.SubjectPublicKeyInfo;
import org.bouncycastle.crypto.params.ECPublicKeyParameters;
import org.bouncycastle.crypto.util.SubjectPublicKeyInfoFactory;
import org.bouncycastle.crypto.util.SubjectPublicKeyInfoParser;
import org.bouncycastle.jcajce.provider.asymmetric.ec.BCECPublicKey;

import java.io.IOException;
import java.io.StringWriter;
import java.security.interfaces.ECPublicKey;

public class SM2Util {

    /**
     * 将SM2公钥转换为PEM格式
     *
     * @param publicKey SM2公钥
     * @return PEM格式的SM2公钥
     * @throws IOException
     */
    public static String publicKeyToPEM(ECPublicKey publicKey) throws IOException {
        SubjectPublicKeyInfo publicKeyInfo = SubjectPublicKeyInfoFactory.createSubjectPublicKeyInfo(new ECPublicKeyParameters(publicKey.getW(), ECUtil.getDomainParameters(publicKey)));
        StringWriter stringWriter = new StringWriter();
        PemWriter pemWriter = new PemWriter(stringWriter);
        pemWriter.writeObject(new PemObject("PUBLIC KEY", publicKeyInfo.getEncoded()));
        pemWriter.close();
        return stringWriter.toString();
    }

    /**
     * 将PEM格式的SM2公钥转换为ECPublicKey对象
     *
     * @param pem PEM格式的SM2公钥
     * @return ECPublicKey对象
     * @throws IOException
     */
    public static ECPublicKey pemToPublicKey(String pem) throws IOException {
        PemReader pemReader = new PemReader(new StringReader(pem));
        PemObject pemObject = pemReader.readPemObject();
        SubjectPublicKeyInfo publicKeyInfo = SubjectPublicKeyInfo.getInstance(pemObject.getContent());
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(publicKeyInfo.getEncoded());
        KeyFactory keyFactory = KeyFactory.getInstance("EC", new BouncyCastleProvider());
        return (ECPublicKey) keyFactory.generatePublic(keySpec);
    }
}

转换后，可以使用文本编辑器打开PEM格式的私钥、公钥文件，查看其中的密钥信息。