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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef EXTENSIONS_BROWSER_VERIFIED_CONTENTS_H_
#define EXTENSIONS_BROWSER_VERIFIED_CONTENTS_H_
#include <map>
#include <string>
#include <vector>
#include "base/files/file_path.h"
#include "base/version.h"
namespace extensions {
// This class encapsulates the data in a "verified_contents.json" file
// generated by the webstore for a .crx file. That data includes a set of
// signed expected hashes of file content which can be used to check for
// corruption of extension files on local disk.
class VerifiedContents {
public:
// This function fixes up a string in base64url encoding to be in standard
// base64.
//
// The JSON signing spec we're following uses "base64url" encoding (RFC 4648
// section 5 without padding). The slight differences from regular base64
// encoding are:
// 1. uses '_' instead of '/'
// 2. uses '-' instead of '+'
// 3. omits trailing '=' padding
static bool FixupBase64Encoding(std::string* input);
// Note: the public_key must remain valid for the lifetime of this object.
VerifiedContents(const uint8* public_key, int public_key_size);
~VerifiedContents();
// Returns true if we successfully parsed the verified_contents.json file at
// |path| and validated the enclosed signature. The
// |ignore_invalid_signature| argument can be set to make this still succeed
// if the contents of the file were parsed successfully but the signature did
// not validate. (Use with caution!)
bool InitFrom(const base::FilePath& path, bool ignore_invalid_signature);
int block_size() const { return block_size_; }
const std::string& extension_id() const { return extension_id_; }
const base::Version& version() const { return version_; }
bool HasTreeHashRoot(const base::FilePath& relative_path) const;
bool TreeHashRootEquals(const base::FilePath& relative_path,
const std::string& expected) const;
// If InitFrom has not been called yet, or was used in "ignore invalid
// signature" mode, this can return false.
bool valid_signature() { return valid_signature_; }
private:
// Returns the base64url-decoded "payload" field from the json at |path|, if
// the signature was valid (or ignore_invalid_signature was set to true).
bool GetPayload(const base::FilePath& path,
std::string* payload,
bool ignore_invalid_signature);
// The |protected_value| and |payload| arguments should be base64url encoded
// strings, and |signature_bytes| should be a byte array. See comments in the
// .cc file on GetPayload for where these come from in the overall input
// file.
bool VerifySignature(const std::string& protected_value,
const std::string& payload,
const std::string& signature_bytes);
// The public key we should use for signature verification.
const uint8* public_key_;
const int public_key_size_;
// Indicates whether the signature was successfully validated or not.
bool valid_signature_;
// The block size used for computing the treehash root hashes.
int block_size_;
// Information about which extension these signed hashes are for.
std::string extension_id_;
base::Version version_;
// The expected treehash root hashes for each file, lower cased so we can do
// case-insensitive lookups.
//
// We use a multi-map here so that we can do fast lookups of paths from
// requests on case-insensitive systems (windows, mac) where the request path
// might not have the exact right capitalization, but not break
// case-sensitive systems (linux, chromeos). TODO(asargent) - we should give
// developers client-side warnings in each of those cases, and have the
// webstore reject the cases they can statically detect. See crbug.com/29941
typedef std::multimap<base::FilePath::StringType, std::string> RootHashes;
RootHashes root_hashes_;
DISALLOW_COPY_AND_ASSIGN(VerifiedContents);
};
} // namespace extensions
#endif // EXTENSIONS_BROWSER_VERIFIED_CONTENTS_H_
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