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如何签署嵌入时间戳并启用LTV的PDF?

digital-signature itext timestamp pdf java

lucasdc · 技术社区 · 7 年前

在英语中,它表示“签名包括嵌入的时间戳”和“签名启用LTV”。以下是我使用的代码:

PrivateKey pk = // get pk from an encrypting certificate created using encrypting file system
Certificate[] chain = ks.getCertificateChain(alias);

PdfReader reader = new PdfReader(src);
FileOutputStream fout = new FileOutputStream(dest);
PdfStamper stp = PdfStamper.createSignature(reader, fout, '\0');

PdfSignatureAppearance sap = stp.getSignatureAppearance();

ExternalSignature signature = new PrivateKeySignature(pk, "SHA-512", "SunMSCAPI");
TSAClient tsc = null;
String url = // TSA URL
tsc = new TSAClientBouncyCastle(url, null, null, 4096, "SHA-512");

List<CrlClient> crlList = new ArrayList<>();
crlList.add(new CrlClientOnline(chain));

ExternalDigest digest = new BouncyCastleDigest();
MakeSignature.signDetached(sap, digest, signature, chain, crlList, null, tsc, 0, CryptoStandard.CMS);

基于 this answer ,我需要一种方法将TSA证书的CRL获取到 CrlList 但是我如何获得TSA证书?我需要做一个 timestamp-query 请求TSA并读取响应,然后将其添加到 CrlList公司 MakeSignature.signDetached 当它呼叫时 sgn.getEncodedPKCS7 . 注意,我使用的是免费的TSA服务器。

时间戳详细信息:

更新

由于它是一个免费的TSA服务器,我只需要在Adobe Trusted Certificates中添加TSA服务器证书,现在它可以工作了。

签名详细信息:

基于 this link 启用LTV意味着验证文件所需的所有信息(减去根证书)都包含在PDF中。因此,如果PDF签名正确,并且包含所有必要的证书和每个证书的有效CRL或OSCP响应,并且如果它包括CRL和OCSP上的签名,而不仅仅是签名证书,则PDF启用LTV。看起来我满足了所有这些要求,还是我遗漏了什么?如果是这样,我怎么知道缺少什么来获得支持LTV的pdf?

1 回复 | 直到 7 年前

lucasdc 7 年前

首先,基于@mkl注释,我将TSA服务器证书添加到Adobe Trusted Certificates中,以便消息

已证实的

签名包括嵌入的时间戳

签名未启用LTV,将在(…)后过期

我注意到使用

List<CrlClient> crlList = new ArrayList<>();
crlList.add(new CrlClientOnline(chain));

// long term validation (LTV)
List<CrlClient> crlList = new ArrayList<>();

for(Certificate cert : chain) {
    X509Certificate c = (X509Certificate)cert;
    List<String> crls = this.getCrlDistributionPoints(c);
    if(crls != null && !crls.isEmpty()) {
        crlList.add(new CrlClientOnline(crls.toArray(new String[crls.size()])));
    }
}

private List<String> getCrlDistributionPoints(final X509Certificate cert) throws Exception {
    final byte[] crldpExt = cert.getExtensionValue(X509Extension.cRLDistributionPoints.getId());
    if (crldpExt == null) {
        final List<String> emptyList = new ArrayList<String>();
        return emptyList;
    }
    ASN1InputStream oAsnInStream = null;
    ASN1InputStream oAsnInStream2 = null;
    List<String> crlUrls = new ArrayList<String>();

    try { 
        oAsnInStream = new ASN1InputStream(new ByteArrayInputStream(crldpExt));
        final ASN1Object derObjCrlDP = oAsnInStream.readObject();
        final DEROctetString dosCrlDP = (DEROctetString) derObjCrlDP;
        final byte[] crldpExtOctets = dosCrlDP.getOctets();
        oAsnInStream2 = new ASN1InputStream(new ByteArrayInputStream(crldpExtOctets));
        final ASN1Object derObj2 = oAsnInStream2.readObject();
        final CRLDistPoint distPoint = CRLDistPoint.getInstance(derObj2);
        for (final DistributionPoint dp : distPoint.getDistributionPoints()) {
            final DistributionPointName dpn = dp.getDistributionPoint();
            // Look for URIs in fullName
            if (dpn != null) {
                if (dpn.getType() == DistributionPointName.FULL_NAME) {
                    final GeneralName[] genNames = GeneralNames.getInstance(dpn.getName()).getNames();
                    // Look for an URI
                    for (int j = 0; j < genNames.length; j++) {
                        if (genNames[j].getTagNo() == GeneralName.uniformResourceIdentifier) {
                            final String url = DERIA5String.getInstance(genNames[j].getName()).getString();
                            crlUrls.add(url);
                        }
                    }
                }
            }
        }
    } catch(IOException e) {
        throw new Exception(e.getMessage(), e);
    } finally {
        IOUtils.closeQuietly(oAsnInStream);
        IOUtils.closeQuietly(oAsnInStream2);
    }

    return crlUrls;
}