Class DiffieHellman

The DiffieHellman class is a utility for creating Diffie-Hellman key exchanges.

Instances of the DiffieHellman class can be created using the createDiffieHellman function.

import assert from 'node:assert';

const {
  createDiffieHellman,
} = await import('node:crypto');

// Generate Alice's keys...
const alice = createDiffieHellman(2048);
const aliceKey = alice.generateKeys();

// Generate Bob's keys...
const bob = createDiffieHellman(alice.getPrime(), alice.getGenerator());
const bobKey = bob.generateKeys();

// Exchange and generate the secret...
const aliceSecret = alice.computeSecret(bobKey);
const bobSecret = bob.computeSecret(aliceKey);

// OK
assert.strictEqual(aliceSecret.toString('hex'), bobSecret.toString('hex'));

Since

v0.5.0

Properties

verifyError

Methods

computeSecret generateKeys getGenerator getPrime getPrivateKey getPublicKey setPrivateKey setPublicKey

Properties

verifyError

verifyError: number

A bit field containing any warnings and/or errors resulting from a check performed during initialization of the DiffieHellman object.

The following values are valid for this property (as defined in node:constants module):

  • DH_CHECK_P_NOT_SAFE_PRIME
  • DH_CHECK_P_NOT_PRIME
  • DH_UNABLE_TO_CHECK_GENERATOR
  • DH_NOT_SUITABLE_GENERATOR

Since

v0.11.12

Methods

computeSecret

  • computeSecret(otherPublicKey, inputEncoding?, outputEncoding?): Buffer

  • Computes the shared secret using otherPublicKey as the other party's public key and returns the computed shared secret. The supplied key is interpreted using the specified inputEncoding, and secret is encoded using specified outputEncoding. If the inputEncoding is not provided, otherPublicKey is expected to be a Buffer, TypedArray, or DataView.

    If outputEncoding is given a string is returned; otherwise, a Buffer is returned.

    Parameters

    • otherPublicKey: ArrayBufferView
    • OptionalinputEncoding: null

      The encoding of an otherPublicKey string.

    • OptionaloutputEncoding: null

      The encoding of the return value.

    Returns Buffer

    Since

    v0.5.0

  • computeSecret(otherPublicKey, inputEncoding, outputEncoding?): Buffer

  • Parameters

    Returns Buffer

  • computeSecret(otherPublicKey, inputEncoding, outputEncoding): string

  • Parameters

    Returns string

  • computeSecret(otherPublicKey, inputEncoding, outputEncoding): string

  • Parameters

    Returns string

generateKeys

  • generateKeys(): Buffer

  • Generates private and public Diffie-Hellman key values unless they have been generated or computed already, and returns the public key in the specified encoding. This key should be transferred to the other party. If encoding is provided a string is returned; otherwise a Buffer is returned.

    This function is a thin wrapper around DH_generate_key(). In particular, once a private key has been generated or set, calling this function only updates the public key but does not generate a new private key.

    Returns Buffer

    Since

    v0.5.0

  • generateKeys(encoding): string

  • Parameters

    Returns string

getGenerator

  • getGenerator(): Buffer

  • Returns the Diffie-Hellman generator in the specified encoding. If encoding is provided a string is returned; otherwise a Buffer is returned.

    Returns Buffer

    Since

    v0.5.0

  • getGenerator(encoding): string

  • Parameters

    Returns string

getPrime

  • getPrime(): Buffer

  • Returns the Diffie-Hellman prime in the specified encoding. If encoding is provided a string is returned; otherwise a Buffer is returned.

    Returns Buffer

    Since

    v0.5.0

  • getPrime(encoding): string

  • Parameters

    Returns string

getPrivateKey

  • getPrivateKey(): Buffer

  • Returns the Diffie-Hellman private key in the specified encoding. If encoding is provided a string is returned; otherwise a Buffer is returned.

    Returns Buffer

    Since

    v0.5.0

  • getPrivateKey(encoding): string

  • Parameters

    Returns string

getPublicKey

  • getPublicKey(): Buffer

  • Returns the Diffie-Hellman public key in the specified encoding. If encoding is provided a string is returned; otherwise a Buffer is returned.

    Returns Buffer

    Since

    v0.5.0

  • getPublicKey(encoding): string

  • Parameters

    Returns string

setPrivateKey

  • setPrivateKey(privateKey): void

  • Sets the Diffie-Hellman private key. If the encoding argument is provided,privateKey is expected to be a string. If no encoding is provided, privateKey is expected to be a Buffer, TypedArray, or DataView.

    This function does not automatically compute the associated public key. Either diffieHellman.setPublicKey() or diffieHellman.generateKeys() can be used to manually provide the public key or to automatically derive it.

    Parameters

    • privateKey: ArrayBufferView

    Returns void

    Since

    v0.5.0

  • setPrivateKey(privateKey, encoding): void

  • Parameters

    • privateKey: string
    • encoding: BufferEncoding

    Returns void

setPublicKey

  • setPublicKey(publicKey): void

  • Sets the Diffie-Hellman public key. If the encoding argument is provided, publicKey is expected to be a string. If no encoding is provided, publicKey is expected to be a Buffer, TypedArray, or DataView.

    Parameters

    • publicKey: ArrayBufferView

    Returns void

    Since

    v0.5.0

  • setPublicKey(publicKey, encoding): void

  • Parameters

    • publicKey: string
    • encoding: BufferEncoding

    Returns void

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