--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/fix-ceb-nulls.lua Mon Aug 01 11:29:27 2022 +0100
@@ -0,0 +1,165 @@
+#!/usr/bin/env lua5.3
+
+if not _VERSION:match("^Lua 5%.[34]") then
+ print("This utility requires Lua 5.3/5.4");
+ return 1;
+end
+
+local have_ciphers, ciphers = pcall(require, "openssl.cipher");
+if not have_ciphers then
+ print("openssl.ciphers module not found.");
+ print("On Debian, install lua-luaossl, or install luarocks and run");
+ print(" luarocks install luaossl");
+ print("");
+end
+
+local have_kdf, kdf = pcall(require, "openssl.kdf");
+if not have_kdf then
+ print("openssl.kdf module not found.");
+ print("On Debian, install lua-luaossl, or install luarocks and run");
+ print(" luarocks install luaossl");
+ print("");
+end
+
+local have_zlib, zlib = pcall(require, "zlib");
+if not have_zlib then
+ print("zlib module not found.");
+ print("On Debian, install lua-zlib, or install luarocks and run");
+ print(" luarocks install lua-zlib");
+ print("");
+end
+
+if #arg == 0 then
+ print("Fix Conversations backup files that contain NUL bytes");
+ print("");
+ print("Usage:");
+ print("");
+ print("", arg[0].." INPUT_FILE PASSWORD");
+ print("");
+ print("On success, a new backup file will be created with the suffix '-fixed.ceb'.");
+ print("");
+end
+
+if #arg == 0 or not have_zlib or not have_kdf or not have_ciphers then
+ return 1;
+end
+
+local input_filename = assert(arg[1], "no ceb file specified");
+
+local file_password = assert(arg[2], "no password specified");
+
+local function read_header(f)
+ local function read_int()
+ return (">i4"):unpack(f:read(4));
+ end
+ local function read_short()
+ return (">i2"):unpack(f:read(2));
+ end
+ local function read_long()
+ return (">i8"):unpack(f:read(8));
+ end
+ local function read_string()
+ local n = read_short();
+ return f:read(n);
+ end
+
+ return {
+ version = read_int();
+ app_id = read_string();
+ jid = read_string();
+ timestamp = math.floor(read_long()/1000);
+ iv = f:read(12);
+ salt = f:read(16);
+ };
+end
+
+local function write_header(f, header)
+ local function write_int(f, n)
+ f:write((">i4"):pack(n));
+ end
+ local function write_short(f, n)
+ f:write((">i2"):pack(n));
+ end
+ local function write_long(f, n)
+ f:write((">i8"):pack(n));
+ end
+ local function write_string(f, s)
+ write_short(f, #s);
+ f:write(s);
+ end
+
+ write_int(f, header.version);
+ write_string(f, header.app_id);
+ write_string(f, header.jid);
+ write_long(f, header.timestamp*1000);
+ assert(#header.iv == 12);
+ f:write(header.iv);
+ assert(#header.salt == 16);
+ f:write(header.salt);
+end
+
+local f = io.open(input_filename);
+
+local header = read_header(f);
+
+print("version", header.version);
+print("app", header.app_id);
+print("jid", header.jid);
+print("timestamp", os.date("%c", header.timestamp));
+
+
+local function generate_key(password, salt)
+ return kdf.derive({
+ type = "PBKDF2";
+ md = "sha1";
+ pass = password;
+ salt = salt;
+ iter = 1024;
+ outlen = 128/8;
+ });
+end
+
+print("k", #(generate_key(file_password, header.salt)));
+
+local decryption_key = generate_key(file_password, header.salt);
+
+local cipher = ciphers.new("AES-128-GCM"):decrypt(decryption_key, header.iv);
+
+local decompress = zlib.inflate();
+
+local compress = zlib.deflate();
+local cipher_out = ciphers.new("AES-128-GCM"):encrypt(decryption_key, header.iv);
+
+local null_replacement = string.char(0xE2, 0x90, 0x80); -- U+2400 SYMBOL FOR NULL
+
+local outfile = assert(io.open(input_filename:gsub("%.ceb$", "-fixed.ceb"), "w+"));
+write_header(outfile, header);
+
+repeat
+ local enc_data = f:read(4096);
+ if not enc_data then break; end
+
+ local gz_data = assert(cipher:update(enc_data));
+
+ local status, data, eof = pcall(decompress, gz_data);
+ if not status then
+ print("EE: Failed to decompress: "..tostring(data));
+ return 1;
+ end
+
+ local status, recompressed = pcall(compress, ((data:gsub("\000", null_replacement))));
+ if not status then
+ print("EE: Failed to compress: "..tostring(data));
+ return 1;
+ end
+ local reencrypted = cipher_out:update(recompressed);
+ outfile:write(reencrypted);
+until eof
+
+local final_data = cipher_out:final();
+if final_data and final_data ~= "" then
+ outfile:write(final_data);
+end
+outfile:close();
+
+print("Done");