摘要 |
Methods and device for digitally signing documents ( 140 ) by using a portable device ( 110 ) that encodes a signature string to sound. The acoustic signature string may be transmitted and then decoded ( 150 ) back into digital data. The signature string may be further processed to verify the signature of the document and to produce a certificate of identity and integrity for the document. The certificate of identity and integrity may be used to further identify and validate the document and its signer. |