A method of authenticating a text document with links to a plurality of files by modifying at least a selected attribute of invisible characters on a plurality of inter-word intervals of the text document, this method comprising the steps of computing (step 10) a one-way hash function of each file in order to obtain a hash value composed of a subset of hash digits for each one, encoding (step 16) each subset of a plurality of subsets of space characters in the document by replacing in each subset of space characters, the value of the selected attribute for each space character by a corresponding encoded hash digit of each subset of hash digits corresponding to each file, computing (step 18) the electronic signature of the encoded text document by using a public-key algorithm composed of a subset of signature digits, and encoding (step 20) another subset of space characters in the encoded document by replacing the value of the selected attribute for each space character by a corresponding encoded signature digit.