src/main/java/cn/jiguang/common/utils/sm2/SM2Util.java
public static byte[] decrypt(ECPrivateKeyParameters priKeyParameters, byte[] sm2Cipher)
        throws InvalidCipherTextException {
        SM2Engine engine = new SM2Engine();
        engine.init(false, priKeyParameters);
        return engine.processBlock(sm2Cipher, 0, sm2Cipher.length);
    }
public static byte[] decrypt(ECPrivateKeyParameters priKeyParameters, byte[] sm2Cipher)
        throws InvalidCipherTextException {
        SM2Engine engine = new SM2Engine();
        engine.init(false, priKeyParameters);
        return engine.processBlock(sm2Cipher, 0, sm2Cipher.length);
    }
ECC私钥解密

@param priKeyParameters ECC私钥
@param sm2Cipher        SM2密文，实际包含三部分：ECC公钥、真正的密文、公钥和原文的SM3-HASH值
@return 原文
@throws InvalidCipherTextException