src/crypto/sha256.js
function hmac(data, key) {
  mctx.init(key);
  mctx.update(data);
  return mctx.finish();
}
function hmac(data, key) {
  mctx.init(key);
  mctx.update(data);
  return mctx.finish();
}
function hmac ( data , key ) { mctx . init ( key ) ; mctx . update ( data ) ; return mctx . finish ( ) ; }
Create a sha256 HMAC from buffer and key.
@alias module:crypto/sha256.hmac
@param {Buffer} data
@param {Buffer} key
@returns {Buffer}
Create a sha256 HMAC from buffer and key .