Hex format validator allows empty and odd-length strings

[ishantiw]

Description

The lisk-validator method that validates hex-encoded data, isHexString, returns true if the provided string is empty ('') or consists of just one hex character (e.g., 'f'):

export const isHexString = (data: unknown): boolean => {
      if (typeof data !== 'string') {
         return false;
       }
  return data === '' || /^[a-f0-9]+$/i.test(data);
};

Both cases will cause a subsequent call to Buffer.from(data, 'hex') to return an empty Buffer object. This may violate the assumption that because the string passed hex format validation, it must encode usable data. Furthermore, when the number of characters is odd but greater than one (e.g., 'fff'), it results in incomplete decoding.

Which version(s) does this affect? (Environment, OS, etc...)

v6.0.0-beta.1

[shuse2]

empty string should return true to represent the empty bytes