expose signature on SignatureContent (#922)

Signed-off-by: Brian DeHamer <bdehamer@github.com>

.changeset/shaggy-hotels-cheat.md

@@ -0,0 +1,5 @@
+---
+"@sigstore/verify": patch
+---
+
+Expose public `signature` property on `SignatureContent` interface

packages/verify/src/bundle/dsse.ts

@@ -37,7 +37,7 @@ export class DSSESignatureContent implements SignatureContent {
     return crypto.verify(this.preAuthEncoding, key, this.signature);
   }
 
-  private get signature(): Buffer {
+  public get signature(): Buffer {
     return this.env.signatures.length > 0
       ? this.env.signatures[0].sig
       : Buffer.from('');

packages/verify/src/bundle/message.ts

@@ -19,7 +19,7 @@ import type { MessageSignature } from '@sigstore/bundle';
 import type { SignatureContent } from '../shared.types';
 
 export class MessageSignatureContent implements SignatureContent {
-  private readonly signature: Buffer;
+  public readonly signature: Buffer;
   private readonly messageDigest: Buffer;
   private readonly artifact: Buffer;
 

packages/verify/src/shared.types.ts

@@ -57,6 +57,7 @@ export type VerificationKey =
     };
 
 export type SignatureContent = {
+  signature: Buffer;
   compareSignature(signature: Buffer): boolean;
   compareDigest(digest: Buffer): boolean;
   verifySignature(key: crypto.KeyObject): boolean;