webcrypto-crypt
v0.2.5
Published
Symmetric cryptography with a passphrase for node and the browser
Downloads
32
Maintainers
Readme
- Introduction
- Install
- Quickstart
- Examples
- Test
- API
- Processing node streams
- Command-line
- Header structure
- Security
- See also
Introduction
webcrypto-crypt encrypts and decrypts data at rest in node or the browser using secret key cryptography in conjunction with a passphrase.
The package will use either the Window.crypto or node-webcrypto-ossl library, depending on where it's running.
Encryption and decryption depend on the key derivation function referred to as PBKDF2 and the symmetric key algorithm called AES-GCM.
For node, the package provides streaming methods and command-line utility wcrypt to deal with files and pipes.
Install
λ npm install -g webcrypto-crypt
Quickstart
Command-line
From prompt
λ wcrypt | wcrypt -d
Data to encrypt: no honour among consultants.
Passphrase?
Confirm passphrase:
Passphrase?
no honour among consultants.λ
From and to file
λ wcrypt -i LICENSE -o LICENSE.wcrypt
Passphrase?
Confirm passphrase:
λ wcrypt -d -i LICENSE.wcrypt
Passphrase?
MIT License
Copyright (c) 2017 C2FO...
From arg
λ wcrypt -a 'edge of a dynastic rebellion' > mydata.wcrypt
Passphrase?
Confirm passphrase:
λ cat mydata.wcrypt | wcrypt -d # or wcrypt -di mydata.wcrypt
Passphrase?
edge of a dynastic rebellionλ
From pipe
λ echo 'pretty despite its implicit threat' | wcrypt | wcrypt -d
Passphrase?
Confirm passphrase:
Passphrase?
pretty despite its implicit threat
Node.js
const Wcrypt = require('webcrypto-crypt')
const wcrypt = new Wcrypt.Cipher('justtesting')
wcrypt.encrypt('no honour among consultants.')
.then((buf) => {
// do something with buf
})
Browser
<html>
<head>
<script src="dist/wcrypt.js"></script>
<script>
var wcrypt = new Wcrypt.Cipher('justtesting');
wcrypt.encrypt('edge of a dynastic rebellion')
.then((buf) => {
console.log('Results %s', buf);
});
</script>
</head>
<body>
</body>
</html>
Examples
Node.js
#!/bin/sh
':' //; exec "$(command -v nodejs || command -v node)" "$0" "$@"
'use strict';
const readlineSync = require('readline-sync')
const Wcrypt = require('webcrypto-crypt')
function askForData () {
return readlineSync.question('Data to encrypt? ')
}
function askForPassphrase () {
return readlineSync
.question('Passphrase to use? ',
{ hideEchoBack: true, mask: '' }
)
}
var wcrypt = new Wcrypt.Cipher(askForPassphrase())
wcrypt.encrypt(askForData())
.then((data) => {
console.log(`
Encrypted, hex-encoded: ${data.toString('hex')},
Encrypted, base64-encoded: ${data.toString('base64')},
Encrypted, web-safe base64-encoded: ${wcrypt.uriSafeBase64(data)},
Decrypted using same passphrase:`
)
wcrypt.decrypt(data)
.then((data) => {
console.log(' ' + Buffer.from(data).toString('utf8'))
})
})
λ node examples/prompts.js
Passphrase to use?
Data to encrypt? ambiguous or even contradictory situations
Encrypted, hex-encoded: c0e82e52c7400925f43e2753249afd8b1527a193917267df53d73d63f287519717c73d3e6c1a3da1797ef19055a49b8402cbb0e10f0a5a294545
Encrypted, base64-encoded: wOguUsdACSX0PidTJJr9ixUnoZORcmffU9c9Y/KHUZcXxz0+bBo9oXl+8ZBVpJuEAsuw4Q8KWilFRQ==
Encrypted, web-safe base64-encoded: wOguUsdACSX0PidTJJr9ixUnoZORcmffU9c9Y_KHUZcXxz0.bBo9oXl.8ZBVpJuEAsuw4Q8KWilFRQ--
Decrypted using same passphrase:
ambiguous or even contradictory situations
λ
Browser
<html>
<head>
<script src="dist/wcrypt.js"></script>
<script>
var wcrypt = new Wcrypt.Cipher(prompt("Secret? "));
wcrypt.encrypt(prompt("Data to encrypt? "))
.then((data) => {
console.log(`
Encrypted, hex-encoded: ${ data.toString("hex") },
Encrypted, base64-encoded: ${ data.toString("base64") },
Encrypted, web-safe base64-encoded: ${ wcrypt.uriSafeBase64(data) },
Decrypted using same passphrase:`
);
wcrypt.decrypt(data)
.then((data) => {
console.log(' ' + Buffer.from(data).toString("utf8"));
});
});
</script>
</head>
<body>
(Check the Developer console.)
</body>
</html>
// In the dev console, after calls to window.prompt() are satisfied, e.g.:
1GTLSRGmdkiAn6pwBB1XWYllS2VgF87h8575Ok2NlIzdH42YgoUFRpFiqbYqj2BKLJEQqoQ-
index.html:11 in a world that allowed such mistakes
Test
Tested environments
| OS | Environment | Version | | :-------- | :------- | :------- | | Mac El Capitan | Chrome | 79.0.3945.130 | | Mac El Capitan | Firefox | 72.0.2 | | Mac El Capitan | Node | v13.9.0 | | Mac El Capitan | Safari | 11.1.2 |
Node.js
λ npm run test
Browsers
A file that should run the module tests in the browser is test/browser/wcrypt-test.html
. webcrypto-crypt currently injects browserify's Buffer
as a global object.
API
Wcrypt.getSignature()
Return the current file signature in use by this library as a Buffer
.
Wcrypt.parseHeader(Buffer data)
Provided data
is a valid webcrypto-wcrypt header, parse it and return an object with the following structure:
{
"material": {
"iv": "<iv>",
"salt": "<salt>",
},
"config": {
"crypto": {
"tagLength": "<tagLength>"
},
"derive": {
"iterations": "<iterations>"
}
}
}
Wcrypt.setHeader(Object config)
Applies this configuration object to the current file header definition.
Wcrypt.DEBUG = true | false
If set to true
, send debugging statements to stderr. Default false
.
new Wcrypt.Cipher(String passphrase || Object options)
Instantiate a webcrypto-crypt object using just a passphrase or more options beyond the passphrase. When passing in an object, the minimum specification looks like {material: { passphrase: <your passphrase> } }
. Possible options are described below:
var wcrypt = new Wcrypt.Cipher({
config: {
crypto: {
usages: [myU1, myU2...], // default ['encrypt', 'decrypt']
tagLength: myTagLength, // default 128
},
delimiter: myDelimiter, // default '<WcRyP+>'
derive: {
hash: myHashFunction, // default 'SHA-512'
iterations: myIterations, // default 2000
length: myLength, // default 128
},
paranoid: true // check each encrypted block
// for incidental presence of
// the delimiter, re-encrypt data
// if detected (very slow).
// default false
},
material: {
iv: myInitializationVector, // default getRandomValues(new Uint8Array(12))
passphrase: 'justtesting', // REQUIRED, passphrase as String
salt: mySalt // default getRandomValues(new Uint8Array(16))
}
})
.then(...
Callers passing in their own value for initialization vector (material.iv
) must ensure that it is never reused under the same key. Likewise, callers passing in their own value for key derivation salt (material.salt
) should ensure it contains data that explicitly distinguishes between different operations.
wcrypt.createHeader()
Return a Buffer
filled with the appropriate seed data for encryption. See these lines.
wcrypt.decrypt(Buffer data)
Decrypt data
by first parsing its header section to extract config
and material
settings. The innvoking wcrypt
object will assume any extracted config
and material
settings for all subsequent operations until overwritten n by reading a different header. Returns a promise with its resolved value set to a Buffer of the decrypted data.
wcrypt.delimiter
The current delimiter in use by this library, e.g., <WcRyP+>
.
wcrypt.encrypt(Buffer data)
Encrypt the given data and include a header. Returns a promise with its resolved value set to a Buffer of the encrypted data.
wcrypt.encryptDelimited(Buffer data)
Encrypt the given data and include a delimiter. Returns a promise with its resolved value set to a Buffer of the encrypted data.
wcrypt.getDelimiter()
Return the delimiter webcrypto-crypt is currently configured to use as a Buffer
.
wcrypt.name
The current name of this library, e.g., webcrypto-crypt
.
wcrypt.rawDecrypt(Buffer data, Object options)
Decrypt data
. Assumes no header present unless assumeHeader: true
is passed in via an options
object. Returns a promise with its resolved value set to a Buffer of the decrypted data.
wcrypt.rawEncrypt(Buffer data, Object options)
Returns a promise with its resolved value set to a Buffer of the encrypted data. The first argument is the data to encrypt. The second argument options
is optional and currently supports two attributes:
wcrypt.rawEncrypt('Some text to encrypt', {appendDelimiter: true});
Will append the wcrypt.delimiter
to the end of the encrypted data before returning it. And:
wcrypt.rawEncrypt('Some text to encrypt', {includeHeader: true});
Will append a cleartext header to the returned data including: initialization vector
, iterations
, salt
, and tagLength
used in the encryption. See these lines.
wcrypt.subtle
The SubtleCrypto object currently in use.
wcrypt.uriSafeBase64(Buffer data)
Convenience method for browser contexts to encode the passed-in data
using web safe base 64 alphabet and return the result.
wcrypt.version
The current version of this library, e.g., 0.1.2
.
Processing node streams
In a node.js environment, webcrypto-crypt/lib/node-streams
provides convenience methods for encrypting and decrypting Readable Streams. Please assume the following lines precede these examples:
const fs = require('fs')
const Wcrypt = require('webcrypto-crypt')
const WcryptStream = require('webcrypto-crypt/lib/node-streams')
const cleartext = 'LICENSE'
const ciphertext = cleartext + '.wcrypt'
Encrypt a readable stream
When encrypting you need to pass in your own wcrypt
object:
const wcrypt = new Wcrypt.Cipher('justtesting')
const clear = fs.createReadStream(cleartext)
const encrypted = fs.createWriteStream(ciphertext)
const read = WcryptStream.encrypt(wcrypt, clear)
read.on('data', (chunk) => {
encrypted.write(chunk)
})
read.on('end', () => {
console.error('wrote ' + ciphertext)
})
Decrypt a readable stream
When decrypting you need to pass in the passphrase:
const decrypt = fs.createReadStream(ciphertext)
const read = WcryptStream.decrypt('justtesting', decrypt)
read.on('data', (chunk) => {
console.log(chunk.toString('utf8'))
})
Command-line
Installing webcrypto-crypt also installs a command-line utilty, wcrypt:
Help
TTY
λ wcrypt -h
Usage: wcrypt [options]
Options:
--debug, -D write debug info to stderr [boolean] [default: "false"]
--help, -h Show help [boolean]
--outfile, -o write data to this file [string]
--infile, -i read data from this file [string]
--arg, -a read data from command line [string]
--decrypt, -d [boolean] [default: false]
Examples:
wcrypt -i msg.txt -o msg.wcrypt file to encrypt
wcrypt -di msg.wcrypt -o msg.txt file to decrypt
wcrypt -a "nonessential appliances" string to encrypt
Piped
λ echo '' | wcrypt -h
Usage: data | wcrypt [options]
Options:
--debug, -D write debug info to stderr [boolean] [default: "false"]
--help, -h Show help [boolean]
--outfile, -o write data to this file [string]
--decrypt, -d [boolean] [default: false]
Examples:
cat msg.txt | wcrypt -o msg.wcrypt encrypt,store in file
cat msg.wcrypt | wcrypt -d decrypt
curl http:..:4196 | wcrypt > aud.wcrypt stream to encrypt
Examples
Note that some of these examples may take a few minutes to download or stream.
Note also that you may set the environment variable WCRYPT_PASSFILE to have wcrypt skip its passphrase prompts.
Text file
λ export TXTFILE_URL="http://web.archive.org/web/20160514230001/http://www.mit.edu/~yandros/doc/command.txt"
λ curl -Ss "$TXTFILE_URL" | wcrypt > command.wcrypt
Passphrase?
Confirm passphrase:
λ wcrypt -di command.wcrypt -o command.txt
Passphrase?
λ less command.txt
Audio file
λ export AUDIO_URL="https://ia802509.us.archive.org/18/items/interview-with-neal-stephenson.JUcDkK.popuparchive.org/focus990527b.mp3"
λ curl -NSs "$AUDIO_URL" | wcrypt > ns-interview.wcrypt # may take a few minutes...
Passphrase?
Confirm passphrase:
λ wcrypt -di ns-interview.wcrypt -o ns-interview.mp3
Passphrase?
λ open ns-interview.mp3
Audio stream
λ export STREAM_URL="http://vprbbc.streamguys.net/vprbbc24-mobile.mp3"
λ curl -NSsm 10 "$STREAM_URL" | wcrypt | wcrypt -d | mpg123 -q -
Passphrase?
Confirm passphrase:
Passphrase?
.wcryptpass
If no passphrase is specified, wcrypt
will consult the environment variable WCRYPT_PASSFILE
and try to use its contents as the path to a file containing the passphrase. If WCRYPT_PASSFILE
is not defined, wcrypt
will check for a .wcryptpass
file in the user's home directory for the same purpose. In either case, on Unix systems the permissions of this file need to disallow access to world or group, achievable with, e.g., chmod 0600 ~/.wcryptpass
. If the permissions are less strict, the file will be ignored.
Header structure
See these lines.
Security
Security Mail: [email protected]
PGP key fingerprint: E838 B51C C63F 7ED6 0980 9535 4D46 5218 A674 6F81
Keyserver: pgp.mit.edu
See also
To do
- Promisify mocha tests
- Improve stream handling
- Add key usage permissions to file header