Task-929640- committed the sample

Author: irfanajaffer

Digital Signature/Extract-PDF-Content-and-Certificate-Metadata-from-p7m-Files/Extract-PDF-Content-and-Certificate-Metadata-from-p7m-Files.slnx

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+<Solution>
+  <Project Path="Extract-PDF-Content-and-Certificate-Metadata-from-p7m-Files/Extract-PDF-Content-and-Certificate-Metadata-from-p7m-Files.csproj" />
+</Solution>

Digital Signature/Extract-PDF-Content-and-Certificate-Metadata-from-p7m-Files/Extract-PDF-Content-and-Certificate-Metadata-from-p7m-Files/Data/TestCert.pdf.p7s

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <RootNamespace>Extract_PDF_Content_and_Certificate_Metadata_from_p7m_Files</RootNamespace>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="System.Security.Cryptography.Cng" Version="5.0.0" />
+    <PackageReference Include="System.Security.Cryptography.Pkcs" Version="9.0.10" />
+  </ItemGroup>
+
+</Project>

Digital Signature/Extract-PDF-Content-and-Certificate-Metadata-from-p7m-Files/Extract-PDF-Content-and-Certificate-Metadata-from-p7m-Files/Extract-PDF-Content-and-Certificate-Metadata-from-p7m-Files.csproj

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+using System.Security.Cryptography;
+using System.Security.Cryptography.Pkcs;
+using System.Security.Cryptography.X509Certificates;
+
+namespace ConsoleApp
+{
+    internal class Program
+    {
+        static void Main(string[] args)
+        {
+            // Load the signed CMS (assumes signedCmsBytes contains the Signed CMS data)
+            byte[] signedCmsBytes = File.ReadAllBytes("../../../TestCert.pdf.p7s");
+
+            SignedCms signedCms = new SignedCms();
+
+            // Decode the Signed CMS data
+            signedCms.Decode(signedCmsBytes);
+
+            // Verify the signature without considering the certificate chain
+            signedCms.CheckSignature(true);
+
+            // Extract the original content
+            byte[] originalMessage = signedCms.ContentInfo.Content;
+            File.WriteAllBytes("D://Decoded.pdf", originalMessage);
+
+            // Extract signer information
+            foreach (SignerInfo signerInfo in signedCms.SignerInfos)
+            {
+                // Get the signing certificate
+                X509Certificate2 signerCertificate = signerInfo.Certificate;
+
+                // Extract signer's name
+                string signerName = signerCertificate?.Subject ?? "Unknown Signer";
+                Console.WriteLine($"Signer Name: {signerName}");
+
+                // Extract signing date (signing time attribute)
+                Pkcs9SigningTime signingTime = null;
+                foreach (var data in from CryptographicAttributeObject attr in signerInfo.SignedAttributes
+                                     from AsnEncodedData data in attr.Values
+                                     where data is Pkcs9SigningTime
+                                     select data)
+                {
+                    signingTime = (Pkcs9SigningTime)data;
+                    break;
+                }
+
+                if (signingTime != null)
+                {
+                    Console.WriteLine($"Signing Time: {signingTime.SigningTime}");
+                }
+                else
+                {
+                    Console.WriteLine("Signing Time: Not available in the attributes.");
+                }
+            }
+        }
+    }
+
+}