Node JS crypto.createCipheriv Error: Invalid key length

Question

I am trying to encrypt text in using node.js crypto module.

Here is code:

const crypto = require('crypto');

const password = 'password';
const key = crypto.scryptSync(password, 'salt', 24);

const iv = crypto.randomBytes(16);
const cipher = crypto.createCipheriv('aes-256-gcm', key, iv);
var encrypted = cipher.update("Hello", 'utf8', 'hex') + cipher.final('hex');

console.log(encrypted);

And I get following error:

internal/crypto/cipher.js:103
    this[kHandle].initiv(cipher, credential, iv, authTagLength);
                  ^

Error: Invalid key length
[90m    at Cipheriv.createCipherBase (internal/crypto/cipher.js:103:19)[39m
[90m    at Cipheriv.createCipherWithIV (internal/crypto/cipher.js:121:20)[39m
[90m    at new Cipheriv (internal/crypto/cipher.js:225:22)[39m
[90m    at Object.createCipheriv (crypto.js:117:10)[39m
    at Object.<anonymous> (F:\Misc\App\MySQL-Buzzer-Electron\demo.js:7:23)
[90m    at Module._compile (internal/modules/cjs/loader.js:1156:30)[39m
[90m    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1176:10)[39m
[90m    at Module.load (internal/modules/cjs/loader.js:1000:32)[39m
[90m    at Function.Module._load (internal/modules/cjs/loader.js:899:14)[39m
[90m    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:74:12)[39m

What am I doing wrong ?

Seti · Accepted Answer · 2020-11-19 11:44:04Z

8

you used aes-256-gmc you need to use key length of 32 and iv of length 16

const crypto = require('crypto');

const password = 'password';
const key = crypto.scryptSync(password, 'salt', 32);

const iv = crypto.randomBytes(16);
const cipher = crypto.createCipheriv('aes-256-gcm', key, iv);
var encrypted = cipher.update("Hello", 'utf8', 'hex') + cipher.final('hex');

answered Nov 19, 2020 at 11:44

Seti

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7 Comments

President James K. Polk Over a year ago

iv length should be 12 for GCM.

Seti Over a year ago

but not for aes-256-gmc

President James K. Polk Over a year ago

There is no such thing as GMC. As you can see, it's GCM.

President James K. Polk Over a year ago

16 will work, but 12 makes more sense as anything else results in extra work to compute the pre-counter block. Please read up on GCM in NIST SP 800-38D, or take a look at RFC 5288 nonce specification.

Artjom B. Over a year ago

@Seti Please read Maarten's answer again. It clearly states that the IV has a default length of 12 bytes for AES-GCM mode (regardless of key size). Yes, it can have a different, but then the IV is hashed ("extra work" as James said) to get the necessary length which would not be necessary if it had the correct length in the first place.

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