Java IText7 PDF 签名问题 - 文档自签名后已被更改或损坏
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【中文标题】Java IText7 PDF 签名问题 - 文档自签名后已被更改或损坏【英文标题】：Java IText7 PDF Sign Problem - Document has been altered or corrupted since it was signed 【发布时间】：2021-11-06 21:03:40 【问题描述】：我尝试签署 pdf 文件，但在 Adobe 中打开已签署的 pdf 文件时遇到“文档自签署后已被更改或损坏”错误。
该错误描述性不强，我不知道该看哪里，因为代码对我来说似乎不错，但显然不是..
我使用的代码是：
public class SafeService_INPUT_Pdf
private static final String input = "";
private static final String tmp = "";
private static final String output = "";
private static final String token = "";
public static void main(String[] args) throws Exception
BouncyCastleProvider providerBC = new BouncyCastleProvider();
Security.addProvider(providerBC);
CredentialsInfoResponseDto credentialsInfoResponseDto = SafeAmaHelper.getCredentialsInfo(token);
String cert0 = "-----BEGIN CERTIFICATE-----\n"+ credentialsInfoResponseDto.getCert().getCertificates().get(0) +"\n-----END CERTIFICATE-----";
String cert1 = "-----BEGIN CERTIFICATE-----\n"+ credentialsInfoResponseDto.getCert().getCertificates().get(1) +"\n-----END CERTIFICATE-----";
String cert2 = "-----BEGIN CERTIFICATE-----\n"+ credentialsInfoResponseDto.getCert().getCertificates().get(2) +"\n-----END CERTIFICATE-----";
Certificate[] chain = new Certificate[3];
try
chain[0] = SafePdfHelper.convertStringCert(cert0);
chain[1] = SafePdfHelper.convertStringCert(cert1);
chain[2] = SafePdfHelper.convertStringCert(cert2);
catch (Exception e)
System.out.println(e.getCause().getMessage());
byte[] hash4Sign = SafePdfHelper.emptySignature(input, tmp, "sig", chain);
//concatenate sha_prefix with hash4Sign and convert to BASE64
String **hashToSign** = SafePdfHelper.getHashtoSign(hash4Sign);
//CALL AMA and gets
String amaSignature = SafeAmaHelper.getAssinat(token,**hashToSign**).getSignatures().get(0);
byte[] signedFinallyHash = Base64.getDecoder().decode(String.valueOf(amaSignature.toCharArray()));
//insert HASH (AMA) to PDF temp and creates a signed PDF
SafePdfHelper.createSignature(signedFinallyHash, tmp, output, "sig", chain);
public class SafePdfHelper
public static String getHashtoSign(byte[] hash4Sign) throws NoSuchAlgorithmException
byte[] sha256SigPrefix = 0x30, 0x31, 0x30, 0x0d, 0x06, 0x09, 0x60, (byte) 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01, 0x05, 0x00, 0x04, 0x20 ;
byte[] hash4SignWithPrefix = new byte[sha256SigPrefix.length + hash4Sign.length];
System.arraycopy(sha256SigPrefix, 0, hash4SignWithPrefix, 0, sha256SigPrefix.length);
System.arraycopy(hash4Sign, 0, hash4SignWithPrefix, sha256SigPrefix.length, hash4Sign.length);
return Base64.getEncoder().encodeToString(hash4SignWithPrefix);
public static Certificate convertStringCert(String certificate) throws Exception
InputStream targetStream = new ByteArrayInputStream(certificate.getBytes());
CertificateFactory cf = CertificateFactory.getInstance("X.509");
Certificate cert = cf.generateCertificate(targetStream);
return cert;
public static byte[] emptySignature(String src, String dest, String fieldname, Certificate[] chain) throws IOException, GeneralSecurityException, IOException
PdfReader reader = new PdfReader(src);
FileOutputStream os = new FileOutputStream(dest);
PdfSigner signer = new PdfSigner(reader, os, new StampingProperties().useAppendMode());
signer.setFieldName(fieldname);
SafePdfHelper.MyExternalBlankSignatureContainer external = new SafePdfHelper.MyExternalBlankSignatureContainer(chain, PdfName.Adobe_PPKMS, PdfName.Adbe_pkcs7_detached);
signer.signExternalContainer(external, 12000);
byte[] hash4Sign = external.getHash4Sign();
os.close();
reader.close();
return hash4Sign;
static class MyExternalBlankSignatureContainer implements IExternalSignatureContainer
/* Signature dictionary. Filter and SubFilter. */
private final PdfDictionary sigDic;
private byte[] hash4Sign = null;
private Certificate[] chain = null;
public MyExternalBlankSignatureContainer(Certificate[] _chain, PdfName filter, PdfName subFilter)
sigDic = new PdfDictionary();
sigDic.put(PdfName.Filter, filter);
sigDic.put(PdfName.SubFilter, subFilter);
chain = _chain;
public byte[] getHash4Sign()
return hash4Sign;
@Override
public byte[] sign(InputStream data) throws GeneralSecurityException
try
String hashAlgorithm = DigestAlgorithms.SHA256;//"SHA-256";
BouncyCastleDigest digest = new BouncyCastleDigest();
MessageDigest md = digest.getMessageDigest(hashAlgorithm);
byte[] hash = DigestAlgorithms.digest(data, md);
PdfPKCS7 sgn = new PdfPKCS7(null, chain, hashAlgorithm, null, digest, false);
OcspClientBouncyCastle ocspClient = new OcspClientBouncyCastle(null);
Collection<byte[]> ocsp = new ArrayList<>();
for (var i = 0; i < chain.length - 1; i++)
byte[] encoded = ocspClient.getEncoded((X509Certificate) chain[i], (X509Certificate) chain[i + 1], null);
if (encoded != null) ocsp.add(encoded);
byte[] attributeBytes = sgn.getAuthenticatedAttributeBytes(hash, PdfSigner.CryptoStandard.CMS, ocsp, null);
//create sha256 message digest
hash4Sign = MessageDigest.getInstance(hashAlgorithm).digest(attributeBytes);
return new byte[0];
catch (IOException | GeneralSecurityException de)
de.printStackTrace();
throw new GeneralSecurityException(de);
@Override
public void modifySigningDictionary(PdfDictionary signDic)
signDic.putAll(sigDic);
public static void createSignature(byte[] hashSigned, String src, String dest, String fieldName, Certificate[] chain) throws IOException, GeneralSecurityException
PdfReader reader = new PdfReader(src);
try (FileOutputStream os = new FileOutputStream(dest))
PdfSigner signer = new PdfSigner(reader, os, new StampingProperties());
IExternalSignatureContainer external = new SafePdfHelper.MyExternalSignatureContainer(hashSigned, chain, PdfName.Adobe_PPKMS, PdfName.Adbe_pkcs7_detached);
// Signs a PDF where space was already reserved. The field must cover the whole document.
signer.signDeferred(signer.getDocument(), fieldName, os, external);
reader.close();
static class MyExternalSignatureContainer implements IExternalSignatureContainer
/* Signature dictionary. Filter and SubFilter. */
private PdfDictionary sigDic;
private byte[] signedHash = null;
private Certificate[] chain = null;
public MyExternalSignatureContainer(byte[] _signedHash, Certificate[] _chain, PdfName filter, PdfName subFilter)
sigDic = new PdfDictionary();
sigDic.put(PdfName.Filter, filter);
sigDic.put(PdfName.SubFilter, subFilter);
signedHash = _signedHash;
chain = _chain;
@Override
public byte[] sign(InputStream data) throws GeneralSecurityException
try
String hashAlgorithm = DigestAlgorithms.SHA256;//"SHA-256";
BouncyCastleDigest digest = new BouncyCastleDigest();
MessageDigest md = digest.getMessageDigest(hashAlgorithm);
byte[] hash = DigestAlgorithms.digest(data, md);
PdfPKCS7 sgn = new PdfPKCS7(null, chain, hashAlgorithm, null, digest, false);
OcspClientBouncyCastle ocspClient = new OcspClientBouncyCastle(null);
Collection<byte[]> ocsp = new ArrayList<>();
for (var i = 0; i < chain.length - 1; i++)
byte[] encoded = ocspClient.getEncoded((X509Certificate) chain[i], (X509Certificate) chain[i + 1], null);
if (encoded != null) ocsp.add(encoded);
sgn.setExternalDigest(signedHash, null, "RSA");
ITSAClient tsaClient = null;//new GSTSAClient(access);
return sgn.getEncodedPKCS7(hash, PdfSigner.CryptoStandard.CMS, tsaClient, ocsp, null);
catch (IOException | GeneralSecurityException de)
de.printStackTrace();
throw new GeneralSecurityException(de);
@Override
public void modifySigningDictionary(PdfDictionary signDic)
signDic.putAll(sigDic);
签名的哈希的Base64格式是（tmp文件+sha_prefix）：
MDEwDQYJYIZIAWUDBAIBBQAEIKCZG8Xc6M2de3fuj8CMHLhW8XvMArW6Smy75TgABlGQ
签名 (AMA) 的 Base64 格式为：
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
谁能帮忙？
【问题讨论】：
格式错误请见谅。 @mkl 你能帮忙吗？ 请分享一个由您的代码签名的示例 PDF。通常，对 PDF 的快速分析可以明确在代码或环境中的何处查找。 啊，一个错误是您在MyExternalBlankSignatureContainer.sign 和 MyExternalSignatureContainer.sign 中都检索到 OCSP 响应。这是错误的，您必须在两种情况下使用相同的 OCSP 响应集，因此您只需检索它们一次，例如在MyExternalBlankSignatureContainer.sign 中，从那里检索它们，然后在MyExternalSignatureContainer.sign 中重新使用它们。如何简化错误搜索并且暂时不检索 OCSP 响应？
成功了！！！谢谢@mkl
【参考方案1】：
这是我们在 cmets 中讨论的概要。
问题是你在MyExternalBlankSignatureContainer.sign 和MyExternalSignatureContainer.sign 中检索OCSP 响应，在你执行的这两种方法中
OcspClientBouncyCastle ocspClient = new OcspClientBouncyCastle(null);
Collection<byte[]> ocsp = new ArrayList<>();
for (var i = 0; i < chain.length - 1; i++)
byte[] encoded = ocspClient.getEncoded((X509Certificate) chain[i], (X509Certificate) chain[i + 1], null);
if (encoded != null) ocsp.add(encoded);
并使用该列表ocsp 和PdfPKCS7。
当您使用MyExternalBlankSignatureContainer 计算要签名的属性的摘要并使用MyExternalSignatureContainer 根据该摘要的签名值构建签名容器时，两种情况下的属性必须相同。由于 OCSP 响应包含在其中一个属性中，这意味着您必须在两种情况下使用相同的 OCSP 响应。
但是 OCSP 响应通常会为每个请求重新创建（或最多缓存很短的时间），对于同一证书的不同请求，您通常会得到不同的 OCSP 响应。
因此，您不得在MyExternalSignatureContainer.sign 中重新检索它们，而是必须重新使用您在MyExternalBlankSignatureContainer.sign 中检索到的那些。
根据您的最终评论，这样做对您有用。
【讨论】：
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