Add some telemetry in order to know what are the certificates used in pdfs (bug 1973573)

src/core/document.js

@@ -1099,6 +1099,49 @@ class PDFDocument {
     });
   }
 
+  #collectSignatureCertificates(
+    fields,
+    collectedSignatureCertificates,
+    visited = new RefSet()
+  ) {
+    if (!Array.isArray(fields)) {
+      return;
+    }
+    for (let field of fields) {
+      if (field instanceof Ref) {
+        if (visited.has(field)) {
+          continue;
+        }
+        visited.put(field);
+      }
+      field = this.xref.fetchIfRef(field);
+      if (!(field instanceof Dict)) {
+        continue;
+      }
+      if (field.has("Kids")) {
+        this.#collectSignatureCertificates(
+          field.get("Kids"),
+          collectedSignatureCertificates,
+          visited
+        );
+        continue;
+      }
+      const isSignature = isName(field.get("FT"), "Sig");
+      if (!isSignature) {
+        continue;
+      }
+      const value = field.get("V");
+      if (!(value instanceof Dict)) {
+        continue;
+      }
+      const subFilter = value.get("SubFilter");
+      if (!(subFilter instanceof Name)) {
+        continue;
+      }
+      collectedSignatureCertificates.add(subFilter.name);
+    }
+  }
+
   get _xfaStreams() {
     const { acroForm } = this.catalog;
     if (!acroForm) {
@@ -1414,6 +1457,20 @@ class PDFDocument {
       // specification).
       const sigFlags = acroForm.get("SigFlags");
       const hasSignatures = !!(sigFlags & 0x1);
+      if (typeof PDFJSDev !== "undefined" && PDFJSDev.test("MOZCENTRAL")) {
+        if (hasSignatures) {
+          const collectedSignatureCertificates = new Set();
+          this.#collectSignatureCertificates(
+            fields,
+            collectedSignatureCertificates
+          );
+          if (collectedSignatureCertificates.size > 0) {
+            formInfo.collectedSignatureCertificates = Array.from(
+              collectedSignatureCertificates
+            );
+          }
+        }
+      }
       const hasOnlyDocumentSignatures =
         hasSignatures && this.#hasOnlyDocumentSignatures(fields);
       formInfo.hasAcroForm = hasFields && !hasOnlyDocumentSignatures;
@@ -1441,6 +1498,11 @@ class PDFDocument {
       IsSignaturesPresent: formInfo.hasSignatures,
     };
 
+    if (typeof PDFJSDev !== "undefined" && PDFJSDev.test("MOZCENTRAL")) {
+      docInfo.collectedSignatureCertificates =
+        formInfo.collectedSignatureCertificates ?? null;
+    }
+
     let infoDict;
     try {
       infoDict = xref.trailer.get("Info");

web/app.js

@@ -1637,6 +1637,13 @@ const PDFViewerApplication = {
     if (pdfDocument !== this.pdfDocument) {
       return; // The document was closed while the metadata resolved.
     }
+    if (info.collectedSignatureCertificates) {
+      this.externalServices.reportTelemetry({
+        type: "signatureCertificates",
+        data: info.collectedSignatureCertificates,
+      });
+    }
+
     this.documentInfo = info;
     this.metadata = metadata;
     this._contentDispositionFilename ??= contentDispositionFilename;