带签名哈希的itextsharp签名pdf
我正在尝试通过签名服务签署pdf。这个服务需要发送一个十六进制编码的SHA256摘要,作为回报,我会收到一个十六进制编码的signatureValue。除此之外,我还收到签名证书、中间证书、OCSP响应和时间戳令牌。然而,我已经在尝试用signatureValue为pdf签名时遇到了麻烦 我读过布鲁诺的白皮书,过度浏览了互联网,尝试了许多不同的方法,但签名一直被认为是无效的 我的最新尝试: 首先,准备pdf带签名哈希的itextsharp签名pdf,pdf,hash,itext,signature,Pdf,Hash,Itext,Signature,我正在尝试通过签名服务签署pdf。这个服务需要发送一个十六进制编码的SHA256摘要,作为回报,我会收到一个十六进制编码的signatureValue。除此之外,我还收到签名证书、中间证书、OCSP响应和时间戳令牌。然而,我已经在尝试用signatureValue为pdf签名时遇到了麻烦 我读过布鲁诺的白皮书,过度浏览了互联网,尝试了许多不同的方法,但签名一直被认为是无效的 我的最新尝试: 首先,准备pdf PdfReader reader = new PdfReader(src); FileS
PdfReader reader = new PdfReader(src);
FileStream os = new FileStream(dest, FileMode.Create);
PdfStamper stamper = PdfStamper.CreateSignature(reader, os, '\0');
PdfSignatureAppearance appearance = stamper.SignatureAppearance;
appearance.Certificate = signingCertificate;
IExternalSignatureContainer external = new ExternalBlankSignatureContainer(PdfName.ADOBE_PPKLITE, PdfName.ADBE_PKCS7_DETACHED);
MakeSignature.SignExternalContainer(appearance, external, 8192);
string hashAlgorithm = "SHA-256";
PdfPKCS7 sgn = new PdfPKCS7(null, chain, hashAlgorithm, false);
PdfSignatureAppearance appearance2 = stamper.SignatureAppearance;
Stream stream = appearance2.GetRangeStream();
byte[] hash = DigestAlgorithms.Digest(stream, hashAlgorithm);
byte[] sh = sgn.getAuthenticatedAttributeBytes(hash, null, null, CryptoStandard.CMS);
散列字节[]sh并转换为字符串,如下所示
private static String sha256_hash(Byte[] value)
{
using (SHA256 hash = SHA256.Create())
{
return String.Concat(hash.ComputeHash(value).Select(item => item.ToString("x2"))).ToUpper();
}
}
并发送到签名服务。接收到的十六进制编码signatureValue I然后转换为字节
private static byte[] StringToByteArray(string hex)
{
return Enumerable.Range(0, hex.Length).Where(x => x % 2 == 0).Select(x => Convert.ToByte(hex.Substring(x, 2), 16)).ToArray();
}
最后,创建签名
private void CreateSignature(string src, string dest, byte[] sig)
{
PdfReader reader = new PdfReader(src); // src is now prepared pdf
FileStream os = new FileStream(dest, FileMode.Create);
IExternalSignatureContainer external = new MyExternalSignatureContainer(sig);
MakeSignature.SignDeferred(reader, "Signature1", os, external);
reader.Close();
os.Close();
}
private class MyExternalSignatureContainer : IExternalSignatureContainer
{
protected byte[] sig;
public MyExternalSignatureContainer(byte[] sig)
{
this.sig = sig;
}
public byte[] Sign(Stream s)
{
return sig;
}
public void ModifySigningDictionary(PdfDictionary signDic) { }
}
我做错了什么?非常感谢您的帮助。谢谢
编辑:当前状态
感谢mkl的帮助,并遵循Bruno的延迟签名示例,我已经克服了无效的签名消息。显然,我没有收到来自签名服务的完整链,而只是一个中间证书,这导致了无效消息。不幸的是,签名仍然有缺陷
我构建的链如下所示:
List<X509Certificate> certificateChain = new List<X509Certificate>
{
signingCertificate,
intermediateCertificate
};
仍然会收到以下消息:
PdfPKCS7
实例构建CMS签名容器
PdfPKCS7 sgn=新的PdfPKCS7(null、chain、hashAlgorithm、false);
对于计算的文档摘要hash
检索要删除的签名属性
byte[]sh=sgn.getAuthenticatedAttributeBytes(哈希、null、null、CryptoStandard.CMS);
发送它们以供签署
到目前为止还不错
但随后您忽略了您开始构建的CMS容器,而是将您从服务中获得的裸签名字节注入到PDF中
这无法工作,因为签名字节不直接对文档进行签名,而是对这些已签名属性进行签名(因此,间接地将文档作为已签名属性之一)。因此,通过忽略正在构造的CMS容器,您删除了实际签名的数据
此外,您使用的子过滤器ADBE_PKCS7_DETACHED承诺嵌入的签名是一个完整的CMS签名容器,而不是几个裸签名字节,因此格式也是错误的
如何取而代之?
您必须在最初开始构建签名容器的PdfPKCS7
实例中将它们设置为外部摘要,而不是将从服务中获得的裸签名字节按原样注入PDF:
public byte[] Sign(Stream s)
{
string hashAlgorithm = "SHA-256";
PdfPKCS7 sgn = new PdfPKCS7(null, chain, hashAlgorithm, false);
byte[] ocspResponse = Convert.FromBase64String("Base64 encoded DER representation of the OCSP response received from signing service");
byte[] hash = DigestAlgorithms.Digest(s, hashAlgorithm);
byte[] sh = sgn.getAuthenticatedAttributeBytes(hash, ocspResponse, null, CryptoStandard.CMS);
string messageDigest = Sha256_hash(sh);
// messageDigest sent to signing service
byte[] signatureAsByte = StringToByteArray("Hex encoded SignatureValue received from signing service");
sgn.SetExternalDigest(signatureAsByte, null, "RSA");
ITSAClient tsaClient = new MyITSAClient();
return sgn.GetEncodedPKCS7(hash, tsaClient, ocspResponse, null, CryptoStandard.CMS);
}
public class MyITSAClient : ITSAClient
{
public int GetTokenSizeEstimate()
{
return 0;
}
public IDigest GetMessageDigest()
{
return new Sha256Digest();
}
public byte[] GetTimeStampToken(byte[] imprint)
{
string hashedImprint = HexEncode(imprint);
// Hex encoded Imprint sent to signing service
return Convert.FromBase64String("Base64 encoded DER representation of TimeStampToken received from signing service");
}
}
sgn.SetExternalDigest(sig,null,加密算法);
(ENCRYPTION\u ALGO
必须是签名算法的加密部分,我假设在您的案例中“RSA”
)
然后您可以检索生成的CMS签名容器:
public byte[] Sign(Stream s)
{
string hashAlgorithm = "SHA-256";
PdfPKCS7 sgn = new PdfPKCS7(null, chain, hashAlgorithm, false);
byte[] ocspResponse = Convert.FromBase64String("Base64 encoded DER representation of the OCSP response received from signing service");
byte[] hash = DigestAlgorithms.Digest(s, hashAlgorithm);
byte[] sh = sgn.getAuthenticatedAttributeBytes(hash, ocspResponse, null, CryptoStandard.CMS);
string messageDigest = Sha256_hash(sh);
// messageDigest sent to signing service
byte[] signatureAsByte = StringToByteArray("Hex encoded SignatureValue received from signing service");
sgn.SetExternalDigest(signatureAsByte, null, "RSA");
ITSAClient tsaClient = new MyITSAClient();
return sgn.GetEncodedPKCS7(hash, tsaClient, ocspResponse, null, CryptoStandard.CMS);
}
public class MyITSAClient : ITSAClient
{
public int GetTokenSizeEstimate()
{
return 0;
}
public IDigest GetMessageDigest()
{
return new Sha256Digest();
}
public byte[] GetTimeStampToken(byte[] imprint)
{
string hashedImprint = HexEncode(imprint);
// Hex encoded Imprint sent to signing service
return Convert.FromBase64String("Base64 encoded DER representation of TimeStampToken received from signing service");
}
}
byte[]encodedSig=sgn.GetEncodedPKCS7(散列、null、null、null、CryptoStandard.CMS);
现在,这是要使用MyExternalSignatureContainer将签名容器注入文档的签名容器:
IExternalSignatureContainer external=新的MyExternalSignatureContainer(encodedSig);
MakeSignature.SignDeferred(读卡器,“Signature1”,操作系统,外部);
遗留问题
更正代码后,Adobe Reader仍会对您的签名发出警告:
MyITSAClient
类中
public字节[]GetTimeStampToken(字节[]压印)
{
字符串hashedImprint=Sha256_散列(压印);
//hashedImprint已发送到签名服务
返回Convert.FromBase64String(“从签名服务接收的TimeStampToken的Base64编码DER表示”);
}
您的GetTimeStampToken
实现的imprint
参数已经过哈希,因此您必须对这些字节进行十六进制编码并发送它们以进行时间戳。但是您可以应用您的方法Sha256_hash
,它首先对这个新的hash进行散列,然后对其进行十六进制编码
因此,不应用Sha256_散列而只对压印进行十六进制编码 “我做错了什么?”-请先说出哪里出了错。最好共享一个由您的代码签名的示例pdf进行分析。Adobe表示签名无效。也看不到证书的详细信息。这里是示例pdf的链接:感谢您的关注。感谢您的明确回答。不幸的是,我还没有完全掌握它。我应该准备带有bla的pdf