AsymmetricAlgorithmSignature

AsymmetricAlgorithmSignature Public class

Description

This class allows you to sign with either an RSACryptoServiceProvider/DSACryptoServiceProvider from a X509Certificate2, or from manually created RSACryptoServiceProvider/DSACryptoServiceProvider. Depending on the certificate's CSP, sometimes you will not be able to sign with SHA-256/SHA-512 hash algorithm with RSACryptoServiceProvider taken directly from the certificate. This class allows you to use a workaround in this case and sign with certificate's private key and SHA-256/SHA-512 anyway.

         An example of a workaround for CSP that does not support SHA-256/SHA-512: ...

Diagram

  flowchart LR
  classDef interfaceStyle stroke-dasharray: 5 5;
  classDef abstractStyle stroke-width:4px
  subgraph iTextSharp.text.pdf.security
  iTextSharp.text.pdf.security.AsymmetricAlgorithmSignature[[AsymmetricAlgorithmSignature]]
  iTextSharp.text.pdf.security.IExternalSignature[[IExternalSignature]]
  class iTextSharp.text.pdf.security.IExternalSignature interfaceStyle;
  end
iTextSharp.text.pdf.security.IExternalSignature --> iTextSharp.text.pdf.security.AsymmetricAlgorithmSignature

Members

Methods

Public methods

Details

Summary

This class allows you to sign with either an RSACryptoServiceProvider/DSACryptoServiceProvider from a X509Certificate2, or from manually created RSACryptoServiceProvider/DSACryptoServiceProvider. Depending on the certificate's CSP, sometimes you will not be able to sign with SHA-256/SHA-512 hash algorithm with RSACryptoServiceProvider taken directly from the certificate. This class allows you to use a workaround in this case and sign with certificate's private key and SHA-256/SHA-512 anyway.

         An example of a workaround for CSP that does not support SHA-256/SHA-512:

                        if (certificate.PrivateKey is RSACryptoServiceProvider)
                        {                
                            RSACryptoServiceProvider rsa = (RSACryptoServiceProvider)certificate.PrivateKey;
            
                            // Modified by J. Arturo
                            // Workaround for SHA-256 and SHA-512
            
                            if (rsa.CspKeyContainerInfo.ProviderName == "Microsoft Strong Cryptographic Provider" ||
                                            rsa.CspKeyContainerInfo.ProviderName == "Microsoft Enhanced Cryptographic Provider v1.0" ||
                                            rsa.CspKeyContainerInfo.ProviderName == "Microsoft Base Cryptographic Provider v1.0")
                            {
                                string providerName = "Microsoft Enhanced RSA and AES Cryptographic Provider";
                                int providerType = 24;
            
                                Type CspKeyContainerInfo_Type = typeof(CspKeyContainerInfo);
            
                                FieldInfo CspKeyContainerInfo_m_parameters = CspKeyContainerInfo_Type.GetField("m_parameters", BindingFlags.NonPublic | BindingFlags.Instance);
                                CspParameters parameters = (CspParameters)CspKeyContainerInfo_m_parameters.GetValue(rsa.CspKeyContainerInfo);
            
                                var cspparams = new CspParameters(providerType, providerName, rsa.CspKeyContainerInfo.KeyContainerName);
                                cspparams.Flags = parameters.Flags;
            
                                using (var rsaKey = new RSACryptoServiceProvider(cspparams))
                                {
                                    // use rsaKey now
                                }
                            }
                            else
                            {
                                // Use rsa directly
                            }
                        }
             

Inheritance

• IExternalSignature

Constructors

AsymmetricAlgorithmSignature [1/2]

Source code

public AsymmetricAlgorithmSignature(RSACryptoServiceProvider algorithm, string hashAlgorithm)

Arguments

AsymmetricAlgorithmSignature [2/2]

Source code

public AsymmetricAlgorithmSignature(DSACryptoServiceProvider algorithm)

Arguments

Methods

Sign

Source code

public virtual byte Sign(byte[] message)

Arguments

GetHashAlgorithm

Source code

public virtual string GetHashAlgorithm()

GetEncryptionAlgorithm

Source code

public virtual string GetEncryptionAlgorithm()

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