Where does SignatureHashAlgorithmExtensions live in the IronPDF API?

SignatureHashAlgorithmExtensions is a static class in the IronPdf.Signing namespace, shipped in IronPdf.dll. It extends System.Object and adds the ToBouncyCastleHashName method directly onto the SignatureHashAlgorithms enum.

How do you get a BouncyCastle hash algorithm name from a SignatureHashAlgorithms value in C#?

Call ToBouncyCastleHashName on any SignatureHashAlgorithms enum value after adding a using directive for IronPdf.Signing. The method returns the string identifier BouncyCastle expects, such as SHA-256, without any additional setup.

Class SignatureHashAlgorithmExtensions

Helpers for SignatureHashAlgorithms.

Inheritance

System.Object

SignatureHashAlgorithmExtensions

Namespace: IronPdf.Signing

Assembly: IronPdf.dll

Syntax

public static class SignatureHashAlgorithmExtensions : Object

Converting a SignatureHashAlgorithms enum value into the string name that BouncyCastle expects is the job SignatureHashAlgorithmExtensions handles. This static extension class lives in IronPdf.Signing and adds ToBouncyCastleHashName directly onto the SignatureHashAlgorithms enum, so the translation reads naturally at the call site without a separate utility call.

ToBouncyCastleHashName returns the canonical hash algorithm identifier string (for example "SHA-256" or "SHA-384") that the BouncyCastle cryptography library accepts when building or verifying a PDF digital signature. IronPDF uses this mapping internally when applying a PdfSignature to a document, but the method is public, making it accessible whenever custom signing pipelines need to bridge the IronPDF enum to a lower-level BouncyCastle API call.

Because the method is an extension, it is invoked on any SignatureHashAlgorithms value directly:

using IronPdf.Signing;

string hashName = SignatureHashAlgorithms.SHA256.ToBouncyCastleHashName();
// hashName == "SHA-256", ready to pass to a BouncyCastle signer

The class itself requires no instantiation and carries no state. Its single responsibility keeps the mapping between IronPDF's signing enum and BouncyCastle's string identifiers in one auditable place, reducing the risk of typos when algorithm names are passed as raw strings across library boundaries.

For broader context on PDF signing in IronPDF, see the digital signature how-to and the PDF signing examples.

Methods

ToBouncyCastleHashName(SignatureHashAlgorithms)

Returns the BouncyCastle digest algorithm name (e.g. "SHA256") for the given signature hash algorithm. PdfPkcs7 resolves this name to the matching digest OID and the {hash}with{RSA|ECDSA|DSA} signer. Unknown values default to SHA-256.

Declaration

public static string ToBouncyCastleHashName(this SignatureHashAlgorithms algorithm)

Parameters

Type	Name	Description
SignatureHashAlgorithms	algorithm	The signature hash algorithm.

Returns

Type	Description
System.String	The BouncyCastle digest algorithm name.