kruptein

kruptein

crypto (krip-toh); from kruptein to hide or conceal.

Sandbox

This started as an exercise in understanding, now has useful functionality.

Here you can experiment with the module to ensure it will suit your needs. kruptein

Install

To install npm install kruptein

Methods

• .set(secret, plaintext, [aad], callback)
• .get(secret, ciphertext, [{at: auth_tag, aad: aad}], callback)

Options

Industry standards are used for the algorithm, hashing algorithm, key & IV sizes. The default key derivation function is pbkdf2, however use of the scrypt or argon2 can be used as well.

• algorithm: (Optional) Cipher algorithm from crypto.getCiphers(). Default: aes-256-gcm.
• hashing: (Optional) Hash algorithm from crypto.getHashes(). Default: sha384.
• encodeas: (Optional) Output encoding. Currently supports binary, hex, & base64. Default: base64.
• key_size: (Optional) Key size bytes (should match block size of algorithm). Default: 32
• iv_size: (Optional) IV size bytes. Default: 16.
• at_size: (Optional) Authentication tag size. Applicable to gcm & ocb cipher modes. Default: 128.
• use_scrypt: (Optional) Use .scrypt() to derive a key. Requires node > v10. Default/Fallback: .pbkdf2().
• use_argon2: (Optional) Use .argon2id() to derive a key. Requires node > v24. Default/Fallback: .pbkdf2().
• use_asn1: (Optional) Disable the default ASN.1 encoding. Default: true
• use_safe_timing: (Optional) In some cases, decryption fails due to tampering validation using crypto.timingSafeEqual.

Usage

When selecting an algorithm from crypto.getCiphers() the iv and key_size values are calculated auto-magically to make implementation easy.

You can always define your own if the defaults per algorithm and mode aren't what you would like; see the options section above.

Create ciphertext from plaintext

An example of creating a new ciphertext object.

const kruptein = require("kruptein")(opts);
let secret = "A$tr0nGp@$S";

kruptein.set(secret, "Some kind of wonderfully private message", (err, ct) => {
  if (err)
    throw err;

  console.log(ct);
});

Get plaintext from ciphertext

An example of retrieveing plaintext from a ciphertext object.

const kruptein = require("kruptein")(opts);
let ciphertext, secret = "A$tr0nGp@$S";

kruptein.get(secret, ciphertext, (err, pt) => {
  if (err)
    throw err;

  console.log(pt);
});

Output

The .set() method output depends on three factors; the encodeas, algorithm and use_asn1.

For any algorithm that supports authentication (AEAD), the object structure includes the Authentication Tag and the Additional Authentication Data attribute and value.

When the use_asn1 option is enabled (default is true), the result is an ASN.1 value using the encodeas value. While this is a more complex encoding option, it helps standardize & minimize the size of the resulting ciphertext output.

Test harness

The included test harness, invoked with npm test, makes every attempt to trap and handle errors. Some of which come from side channel or possible malability of the resultant ciphertext.

This can be seen within the test/index.js CI test harness under the HMAC, AT & AAD validation test cases.

References

This module conforms to industry recommendations regarding algorithm type, mode, key size, iv size & implementation, digests, key derivation & management etc. References used provided here:

RFC:

• RFC 2104: HMAC: Keyed-Hashing for Message Authentication
• RFC 4086: Randomness Requirements for Security
• RFC 5084: Using AES-CCM and AES-GCM Authenticated Encryption
• RFC 7914: The scrypt Password-Based Key Derivation Function
• RFC 8018: Password-Based Cryptography Specification
• RFC 9106: Argon2 Memory-Hard Function for Password Hashing and Proof-of-Work Applications
• X.697: ASN.1 encoding rules: Specifications of JavaScript Object Notation Encoding Rules (JER)

NIST:

• SP 800-38A: Block cipher modes of operation
• SP 800-38B: Recommendation for Block Cipher Modes of Operation: Galois/Counter Mode (GCM) and GMAC
• SP 800-57P1: Recommendations for key management
• SP 800-107: Recommendation for Applications Using Approved Hash Algorithms
• SP 800-108: Recommendation for Key Derivation Using Pseudorandom Functions
• SP 800-131A: Transitioning the Use of Cryptographic Algorithms and Key Lengths
• SP 800-132: Recommendation for Password-Based Key Derivation
• SP 800-175B: Guideline for Using Cryptographic Standards in the Federal Government

FIPS:

• FIPS 197: Advanced Encryption Standard (AES)
• FIPS 198-1: The Keyed-Hash Message Authentication Code (HMAC)
• FIPS 180-4: Secure Hash Standard (SHS)

Contributing

Contributions are welcome & appreciated!

Refer to the contributing document to help facilitate pull requests.

License

This software is licensed under the MIT License.

Copyright Jason Gerfen, 2019.