public class SignatureServiceDisconnected implements SignatureService {

    public static final String STR_CMS_OID_SIGNED = "1.2.840.113549.1.7.2";
    public static final String STR_CMS_OID_DATA = "1.2.840.113549.1.7.1";
    public static final String STR_CMS_OID_CONT_TYP_ATTR = "1.2.840.113549.1.9.3";
    public static final String STR_CMS_OID_DIGEST_ATTR = "1.2.840.113549.1.9.4";
    public static final String STR_CMS_OID_SIGN_TYM_ATTR = "1.2.840.113549.1.9.5";
    private final KeyStore keyStore;

    @Override
    public String signature(Container<?> container, SigningDocumentRequest signingDocument) throws Exception {
        JCPPrivateKeyEntry entry = (JCPPrivateKeyEntry) (Object) keyStore.getEntry(
                container.getAlias(),
                new KeyStore.PasswordProtection(container.getPassword().toCharArray())
        );
        PrivateKey privateKey = entry.getPrivateKey();
        Certificate certificate = entry.getCertificate();

        byte[] data = Base64.getDecoder().decode(signingDocument.document());

        byte[] hashCMSEx = createHashCMSEx(data, new PrivateKey[]{privateKey}, new Certificate[]{certificate});

        return Base64.getEncoder().encodeToString(hashCMSEx);
    }
    
    private static byte[] createHashCMSEx(byte[] data, PrivateKey[] keys, Certificate[] certs) throws Exception {
        //create hashCMS
        final ContentInfo all = new ContentInfo();
        all.contentType = new Asn1ObjectIdentifier(new OID(STR_CMS_OID_SIGNED).value);

        final SignedData cms = new SignedData();
        all.content = cms;
        cms.version = new CMSVersion(1);

        // digest
        cms.digestAlgorithms = new DigestAlgorithmIdentifiers(1);
        final DigestAlgorithmIdentifier a = new DigestAlgorithmIdentifier(new OID(JCP.GOST_DIGEST_OID).value);
        a.parameters = new Asn1Null();
        cms.digestAlgorithms.elements[0] = a;

        // Нельзя сделать подпись совмещенной, если нет данных, а
        // есть только хеш с них.
        cms.encapContentInfo = new EncapsulatedContentInfo(new Asn1ObjectIdentifier(new OID(STR_CMS_OID_DATA).value), null);

        // certificates
        final int nCerts = certs.length;
        cms.certificates = new CertificateSet(nCerts);
        cms.certificates.elements = new CertificateChoices[nCerts];

        for (int i = 0; i < cms.certificates.elements.length; i++) {
            final ru.CryptoPro.JCP.ASN.PKIX1Explicit88.Certificate certificate = new ru.CryptoPro.JCP.ASN.PKIX1Explicit88.Certificate();
            final Asn1BerDecodeBuffer decodeBuffer = new Asn1BerDecodeBuffer(certs[i].getEncoded());
            certificate.decode(decodeBuffer);
            cms.certificates.elements[i] = new CertificateChoices();
            cms.certificates.elements[i].set_certificate(certificate);
        }

        // Signature.getInstance
        final Signature signature = Signature.getInstance(JCP.GOST_SIGN_2012_256_NAME, JCP.PROVIDER_NAME);
        byte[] sign;

        // signer infos
        final int nsign = keys.length;
        cms.signerInfos = new SignerInfos(nsign);
        for (int i = 0; i < cms.signerInfos.elements.length; i++) {
            cms.signerInfos.elements[i] = new SignerInfo();
            cms.signerInfos.elements[i].version = new CMSVersion(1);
            cms.signerInfos.elements[i].sid = new SignerIdentifier();
            final byte[] encodedName = ((X509Certificate) certs[i]).getIssuerX500Principal().getEncoded();
            final Asn1BerDecodeBuffer nameBuf = new Asn1BerDecodeBuffer(encodedName);
            final Name name = new Name();
            name.decode(nameBuf);
            final CertificateSerialNumber num = new CertificateSerialNumber(((X509Certificate) certs[i]).getSerialNumber());
            cms.signerInfos.elements[i].sid.set_issuerAndSerialNumber(new IssuerAndSerialNumber(name, num));
            cms.signerInfos.elements[i].digestAlgorithm = new DigestAlgorithmIdentifier(new OID(JCP.GOST_DIGEST_OID).value);
            cms.signerInfos.elements[i].digestAlgorithm.parameters = new Asn1Null();
            cms.signerInfos.elements[i].signatureAlgorithm = new SignatureAlgorithmIdentifier(new OID(JCP.GOST_EL_KEY_OID).value);
            cms.signerInfos.elements[i].signatureAlgorithm.parameters = new Asn1Null();

            //signedAttributes
            final int kmax = 3;
            cms.signerInfos.elements[i].signedAttrs = new SignedAttributes(kmax);

            //-contentType
            int k = 0;
            cms.signerInfos.elements[i].signedAttrs.elements[k] = new Attribute(
                    new OID(STR_CMS_OID_CONT_TYP_ATTR).value,
                    new Attribute_values(1)
            );

            final Asn1Type conttype = new Asn1ObjectIdentifier(new OID(STR_CMS_OID_DATA).value);

            cms.signerInfos.elements[i].signedAttrs.elements[k].values.elements[0] = conttype;

            //-Time
            k += 1;
            cms.signerInfos.elements[i].signedAttrs.elements[k] = new Attribute(
                    new OID(STR_CMS_OID_SIGN_TYM_ATTR).value,
                    new Attribute_values(1)
            );

            final Time time = new Time();

            final Asn1UTCTime utcTime = new Asn1UTCTime();
            //текущая дата с календаря
            utcTime.setTime(Calendar.getInstance());
            time.set_utcTime(utcTime);

            cms.signerInfos.elements[i].signedAttrs.elements[k].values.elements[0] = time.getElement();

            //-message digest
            k += 1;
            cms.signerInfos.elements[i].signedAttrs.elements[k] = new Attribute(
                    new OID(STR_CMS_OID_DIGEST_ATTR).value,
                    new Attribute_values(1)
            );

            final byte[] messageDigestBlob;

            // Если вместо данных у нас хеш, то сразу его передаем, ничего не вычисляем.
            messageDigestBlob = digestm(data, JCP.GOST_DIGEST_2012_256_NAME, JCP.PROVIDER_NAME);

            final Asn1Type messageDigest = new Asn1OctetString(messageDigestBlob);
            cms.signerInfos.elements[i].signedAttrs.elements[k].values.elements[0] = messageDigest;

            // Добавление signingCertificateV2 в подписанные аттрибуты, чтобы подпись
            // стала похожа на CAdES-BES.

            //signature
            Asn1BerEncodeBuffer encBufSignedAttr = new Asn1BerEncodeBuffer();
            cms.signerInfos.elements[i].signedAttrs.encode(encBufSignedAttr);
            final byte[] hsign = encBufSignedAttr.getMsgCopy();
            signature.initSign(keys[i]);
            signature.update(hsign);
            sign = signature.sign();

            cms.signerInfos.elements[i].signature = new SignatureValue(sign);
        }
        // encode
        final Asn1BerEncodeBuffer asnBuf = new Asn1BerEncodeBuffer();
        all.encode(asnBuf, true);
        return asnBuf.getMsgCopy();
    }

    public static byte[] digestm(byte[] bytes, String digestAlgorithmName, String providerName) throws Exception {
        final ByteArrayInputStream stream = new ByteArrayInputStream(bytes);
        final java.security.MessageDigest digest = providerName != null
                ? java.security.MessageDigest.getInstance(digestAlgorithmName, providerName)
                : MessageDigest.getInstance(digestAlgorithmName);

        final DigestInputStream digestStream = new DigestInputStream(stream, digest);
        while (digestStream.available() != 0) {
            digestStream.read();
        }
        return digest.digest();
    }
}