class

crypto.DiffieHellman

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'));
  • 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
  • otherPublicKey: BinaryLike,
    inputEncoding?: BufferEncoding
    ): NonSharedBuffer;

    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.

    @param inputEncoding

    The encoding of an otherPublicKey string.

    otherPublicKey: BinaryLike,
    inputEncoding: undefined | null | BufferEncoding,
    outputEncoding: BufferEncoding
    ): string;

    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.

    @param inputEncoding

    The encoding of an otherPublicKey string.

    @param outputEncoding

    The encoding of the return value.

  • generateKeys(): NonSharedBuffer;

    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 recomputes the public key from the existing private key. Since the public key is determined by the private key, the result will be the same unless the private key has been changed via diffieHellman.setPrivateKey().

    encoding: BufferEncoding
    ): string;

    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 recomputes the public key from the existing private key. Since the public key is determined by the private key, the result will be the same unless the private key has been changed via diffieHellman.setPrivateKey().

    @param encoding

    The encoding of the return value.

  • getGenerator(): NonSharedBuffer;

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

    encoding: BufferEncoding
    ): string;

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

    @param encoding

    The encoding of the return value.

  • getPrime(): NonSharedBuffer;

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

    encoding: BufferEncoding
    ): string;

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

    @param encoding

    The encoding of the return value.

  • getPrivateKey(): NonSharedBuffer;

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

    encoding: BufferEncoding
    ): string;

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

    @param encoding

    The encoding of the return value.

  • getPublicKey(): NonSharedBuffer;

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

    encoding: BufferEncoding
    ): string;

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

    @param encoding

    The encoding of the return value.

  • privateKey: BinaryLike,
    encoding?: BufferEncoding
    ): 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.

    @param encoding

    The encoding of the privateKey string.

  • publicKey: BinaryLike,
    encoding?: BufferEncoding
    ): 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.

    @param encoding

    The encoding of the publicKey string.