Experimant: EPUB encryption support test

vivliostyle · Jul 7, 2023 · 72f109e · 72f109e
1 parent 9617665
commit 72f109e
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Showing 3 changed files with 136 additions and 1 deletion.
diff --git a/packages/core/src/vivliostyle/epub.ts b/packages/core/src/vivliostyle/epub.ts
@@ -488,6 +488,65 @@ export function makeDeobfuscator(uid: string): (p1: Blob) => Task.Result<Blob> {
   };
 }
 
+export function makeDecrypter(uid: string): (p1: Blob) => Task.Result<Blob> {
+  // for test
+  const hexKey =
+    "87fb7a5c9358aa21d1ea991d9f17781c20c3d420718f6342592e06b0421a220c";
+  const rawKey = new Uint8Array(32);
+  for (let i = 0; i < 32; i++) {
+    rawKey[i] = parseInt(hexKey.substr(i * 2, 2), 16);
+  }
+  return (blob) => {
+    const frame = Task.newFrame("decrypter") as Task.Frame<Blob>;
+
+    makeCryptoKey(rawKey).then((key) => {
+      Net.readBlob(blob).then((buf) => {
+        const iv = buf.slice(0, 16);
+        const cipher = buf.slice(16);
+
+        doDecrypt(key, iv, cipher).then((buf) => {
+          frame.finish(Net.makeBlob([buf]));
+        });
+      });
+    });
+
+    return frame.result();
+  };
+}
+
+function makeCryptoKey(rawKey: Uint8Array): Task.Result<CryptoKey> {
+  const frame: Task.Frame<CryptoKey> = Task.newFrame("makeCryptoKey");
+  const continuation = frame.suspend();
+  window.crypto.subtle
+    .importKey("raw", rawKey, "AES-CBC", true, ["decrypt"])
+    .then((key) => {
+      continuation.schedule(key);
+    });
+  return frame.result();
+}
+
+function doDecrypt(
+  key: CryptoKey,
+  iv: ArrayBuffer,
+  cipher: ArrayBuffer,
+): Task.Result<ArrayBuffer> {
+  const frame: Task.Frame<ArrayBuffer> = Task.newFrame("doDecrypt");
+  const continuation = frame.suspend();
+  window.crypto.subtle
+    .decrypt(
+      {
+        name: "AES-CBC",
+        iv: iv,
+      },
+      key,
+      cipher,
+    )
+    .then((buf) => {
+      continuation.schedule(buf);
+    });
+  return frame.result();
+}
+
 type RawMeta = {
   [key: string]: RawMetaItem[];
 };
@@ -954,6 +1013,24 @@ export class OPFDoc {
           .child("CipherData")
           .child("CipherReference")
           .attribute("URI");
+    const cryptoURLs = !encXML
+      ? []
+      : encXML
+          .doc()
+          .child("encryption")
+          .child("EncryptedData")
+          .predicate(
+            XmlDoc.predicate.withChild(
+              "EncryptionMethod",
+              XmlDoc.predicate.withAttribute(
+                "Algorithm",
+                "http://www.w3.org/2001/04/xmlenc#aes256-cbc",
+              ),
+            ),
+          )
+          .child("CipherData")
+          .child("CipherReference")
+          .attribute("URI");
     const mediaTypeElems = pkg
       .child("bindings")
       .child("mediaType")
@@ -984,6 +1061,12 @@ export class OPFDoc {
         this.store.deobfuscators[this.pubURL + idpfObfURLs[i]] = deobfuscator;
       }
     }
+    if (cryptoURLs.length > 0 && this.uid) {
+      const decrypter = makeDecrypter(this.uid);
+      for (let i = 0; i < cryptoURLs.length; i++) {
+        Net.epubDecrypters[this.pubURL + cryptoURLs[i]] = decrypter;
+      }
+    }
     if (this.prePaginated) {
       this.assignAutoPages();
     }

diff --git a/packages/core/src/vivliostyle/net.ts b/packages/core/src/vivliostyle/net.ts
@@ -39,6 +39,9 @@ export enum XMLHttpRequestResponseType {
 
 export type Response = Net.Response;
 
+export let epubDecrypters: { [key: string]: (p1: Blob) => Task.Result<Blob> } =
+  {};
+
 export function ajax(
   url: string,
   opt_type?: XMLHttpRequestResponseType,
@@ -47,6 +50,31 @@ export function ajax(
   opt_contentType?: string,
 ): Task.Result<Response> {
   const frame: Task.Frame<Response> = Task.newFrame("ajax");
+
+  const decrypter =
+    opt_type === XMLHttpRequestResponseType.BLOB ? null : epubDecrypters?.[url];
+  if (decrypter) {
+    ajax(url, XMLHttpRequestResponseType.BLOB).then((xhr1) => {
+      if (!xhr1.responseBlob) {
+        frame.finish(xhr1);
+        return;
+      }
+      decrypter(xhr1.responseBlob).then((blob) => {
+        ajax(
+          createObjectURL(blob),
+          opt_type,
+          opt_method,
+          opt_data,
+          opt_contentType,
+        ).then((xhr2) => {
+          xhr2.url = url;
+          frame.finish(xhr2);
+        });
+      });
+    });
+    return frame.result();
+  }
+
   const request = new XMLHttpRequest();
   const continuation = frame.suspend(request);
   const response: Response = {
@@ -322,6 +350,24 @@ export function loadElement(
 ): TaskUtil.Fetcher<string> {
   const fetcher = new TaskUtil.Fetcher(() => {
     const frame: Task.Frame<string> = Task.newFrame("loadElement");
+
+    const decrypter = epubDecrypters?.[src];
+    if (decrypter) {
+      ajax(src, XMLHttpRequestResponseType.BLOB).then((xhr) => {
+        if (!xhr.responseBlob) {
+          frame.finish("error");
+          return;
+        }
+        decrypter(xhr.responseBlob).then((blob) => {
+          const fetcher2 = loadElement(elem, createObjectURL(blob));
+          fetcher2.get().then((type) => {
+            frame.finish(type);
+          });
+        });
+      });
+      return frame.result();
+    }
+
     const continuation = frame.suspend(elem);
     let done = false;
     const handler = (evt: Event) => {

diff --git a/packages/core/src/vivliostyle/vgen.ts b/packages/core/src/vivliostyle/vgen.ts
@@ -1417,7 +1417,13 @@ export class ViewFactory
             }
             return false;
           };
-          if (!hasAutoWidth && !hasAutoHeight && !isInsideRunningElement()) {
+          const decrypter = Net.epubDecrypters?.[delayedSrc];
+          if (
+            !decrypter &&
+            !hasAutoWidth &&
+            !hasAutoHeight &&
+            !isInsideRunningElement()
+          ) {
             // No need to wait for the image, does not affect layout
             this.page.fetchers.push(imageFetcher);
           } else {