Class ExternalSignerBase

Base helper implementation for building external (client supplied) digital signatures.

Inheritance
System.Object
ExternalSignerBase
Inherited Members
System.Object.ToString()
System.Object.Equals(System.Object)
System.Object.Equals(System.Object, System.Object)
System.Object.ReferenceEquals(System.Object, System.Object)
System.Object.GetHashCode()
System.Object.GetType()
System.Object.MemberwiseClone()
Namespace: Telerik.Documents.Fixed.Model.DigitalSignatures
Assembly: Telerik.Windows.Documents.Fixed.dll

Syntax

public abstract class ExternalSignerBase : IExternalSigner
Remarks

Implementations provide the signing certificate chain (public keys) and the raw data signing routine (private key operation) while the PDF processing library constructs the CMS (PKCS#7) detached signature container. This allows integrating hardware devices (HSM, smart card), remote signing services, or custom cryptographic stacks without exposing the private key material to the library.

Typical usage: derive a class, override GetCertificateChain() to return the X.509 certificate chain that will be embedded in the CMS structure, and override SignData(Byte[], SignatureSettings) to invoke the external signing facility over the DER-encoded signed attributes. The infrastructure will call the explicit Sign(Byte[], SignatureSettings) implementation to obtain the final CMS encoded byte array that is written into the PDF signature field.

Constructors

ExternalSignerBase()

Initializes a new instance of the ExternalSignerBase class.

Declaration
protected ExternalSignerBase()

Methods

GetCertificateChain()

Returns the X.509 certificate chain associated with the signer.

Declaration
protected abstract X509Certificate2[] GetCertificateChain()
Returns
System.Security.Cryptography.X509Certificates.X509Certificate2[]

An array of X.509 certificates forming the signing certificate chain. Must not be null or empty. The first element must be the signing (leaf) certificate.
Remarks

This should return an ordered array of certificates starting with the end-entity (leaf) certificate whose corresponding private key (or signing capability) is used in SignData(Byte[], SignatureSettings), followed by any intermediate CA certificates needed to establish a trust chain. The root certificate is typically excluded. Implementors may cache the certificates or retrieve them dynamically from a device/service. The library validates that the returned array is not null or empty.

SignData(Byte[], SignatureSettings)

Performs the raw cryptographic signing operation over the DER-encoded signed attributes.

Declaration
protected abstract byte[] SignData(byte[] dataToSign, SignatureSettings settings)
Parameters
System.Byte[] dataToSign

The DER-encoded signed attributes (CMS SignedAttributes) that must be signed. This includes the message digest, content type, signing time, and signing certificate reference.
SignatureSettings settings

Signature generation settings (e.g. digest algorithm, timestamp server).
Returns
System.Byte[]

Binary signature value for the provided signed attributes.
Remarks

The method should return the raw signature bytes appropriate for the public key type (e.g. RSA signature (PKCS#1 v1.5) or ECDSA signature). For ECDSA, the signature can be either raw format (r||s concatenated) or DER-encoded (SEQUENCE { r, s }); the infrastructure will handle the conversion if needed. The surrounding infrastructure will insert this value into the CMS (PKCS#7) SignerInfo structure.

Explicit Interface Implementations

IExternalSigner.Sign(Byte[], SignatureSettings)

Builds a detached CMS (PKCS#7) signature for the provided PDF byte range data using the supplied settings.

Declaration
byte[] IExternalSigner.Sign(byte[] pdfByteRangeData, SignatureSettings settings)
Parameters
System.Byte[] pdfByteRangeData

The raw PDF byte range data (document content excluding the signature placeholder) whose digest will be computed and signed.
SignatureSettings settings

Signature generation settings controlling digest algorithm and timestamping.
Returns
System.Byte[]

Byte array containing the CMS SignedData structure (detached) ready for embedding in a PDF.
Implements