求助， golang 签名数据放入数字信封问题

之前在 java 用 bouncycastle 库对数据进行 SHA1withRSA 签名后，将签名放置到数字信封里。 现在要用 go 重写这段代码，但是谷歌好久也找不到该如何实现，求助该如何实现。

java 代码如下：

            CertDTO certDto = CertUtil.getCertInfo(password, cert);
            X509Certificate cerx509 = certDto.getCert()[0];
            List<X509Certificate> certList = new ArrayList();
            CMSTypedData msg = new CMSProcessableByteArray(data);
            certList.add(cerx509);
            Store certs = new JcaCertStore(certList);
            CMSSignedDataGenerator gen = new CMSSignedDataGenerator();
            ContentSigner sha1Signer = (new JcaContentSignerBuilder("SHA1withRSA"))
                .setProvider("BC").build(certDto.getPriKey());
            gen.addSignerInfoGenerator((new JcaSignerInfoGeneratorBuilder((
                new JcaDigestCalculatorProviderBuilder())
                .setProvider("BC").build())).build(sha1Signer, cerx509));
            gen.addCertificates(certs);
            CMSSignedData sigData = gen.generate(msg, isDetach);
            signedData = sigData.getEncoded();