MP4Crypt

MP4 encrypt-decrypt tools with some features :

• encrypt from file or readable stream source
• decrypt from file or readable stream source
• perform partial decrypt

Beside from MP4, another types of file are supported. Especially if partial decryption are needed.

Instalation

Make sure Node.js and npm already installed

node -v
v16.14.2

npm -v
8.5.0

Open your terminal or CMD and type the following

git clone https://github.com/galaparadi/mp4crypt.git
cd mp4crypt
npm link

after instalation, go to your working directory, and type the following

npm link mp4crypt

Usage

Encrypt file

To encrypt a file, you can use the encrypt method and pipe it to fs.createWriteStream.

const { encrypt } = require('mp4crypt');
const { createWriteableStream } = require('fs');

const sourcePath = "<your file location>";
const secret = "<your secret key>";
const destinationPath = "<your destination file location>"

encrypt({sourcePath, secret})
    .pipe(createWriteStream(destinationPath);

Encrypt file from readable stream

To encrypt data from readable stream (stream.Readable), use encryptStream method instead. To use it, pipe encryptStream to the plain data's readable stream, and then pipe it to writeable stream to get the encrypted data.

const { encryptStream } = require('mp4crypt');
const { createReadableStream } = require('fs')
const { createWriteableStream } = require('fs');

const sourcePath = "<your file location>";
const secret = "<your secret key>";
const destinationPath = "<your destination file location>"
const size = "<filesize>"

createReadableStream(sourcePath)
    .pipe(encryptStream({size, secret}))
    .pipe(createWriteStream(destinationPath);

Decrypt file

To decrypt an encrypted data, start and end byte of the plain data and your secret key must be provided.

const { decrypt, getValidDechiperPositionBlock } = require('mp4crypt');
const { createWriteableStream } = require('fs');

const sourcePath = "<your file location>";
const secret = "<your secret key>";
const destinationPath = "<your destination file location>";
const start = "<your start byte of plain file>";
const end = "<your end byte of plain file>";

decrypt({sourcePath, secret, start, end})
    .pipe(createWriteStream(destinationPath);

Decrypt file from readable stream

To decrypt from readable stream, the iv of the encrypted data must be provided.

To get the iv, the position of the iv is required. Use getIvPosition method to get the iv. After getting the iv position, use the iv position to get the iv byte from the encrypted data.

const { decrypt, getValidDechiperPositionBlock, getIvPosition } = require('mp4crypt');
const { createReadbleStream, createWriteableStream, openSync } = require('fs');

const sourcePath = "<your file location>";
const secret = "<your secret key>";
const destinationPath = "<your destination file location>";
const [start, end] = getValidDechiperPositionBlock(startByte, endByte);
const fd = openSync(join(__dirname, sourcePath), 'r');
const iv = Buffer.alloc(16);
const [ivStart, _] = getIvPosition(startByte);
readSync(fd, iv, 0, 16, ivStart);

createReadableStream(sourcePath, {start, end})
    .pipe(decryptStream({secret, start, end, iv}))
    .pipe(createWriteStream(destinationPath);

API

encrypt({sourcePath: String, secret: String}): stream.Writeable

params :

• sourcePath <String> : path location of your plain file
• secret <String> : your secret key

return : <Writeable>

decrypt({path: String, secret: String, start: Number, end: Number}): stream.Writeable

params :

• path <String> : path location of your encrypted file
• secret <String> : your secret key
• start <Number> : start byte of plain file
• end <Number> : end byte of plain file

return : <Writeable>

encryptStream({secret: String, size: Number}): stream.Duplex

params :

• secret <String> : your secret key
• size <Number> : the size of plain data

return : <Duplex>

decryptStream({secret: String, start: Number, end: Number, iv: Buffer}): stream.Duplex

params :

• secret <String> : your secret key
• size <Number> : the size of plain data
• start <Number> : start byte of plain data
• end <Number> : end byte of plain data
• iv <Buffer> : buffer iv for encrypting data

return : <Duplex>

Contributing

Feel free to contribute on this repository.

License

MIT

Author

galaparadi