Patent ID: 8078878

Claim:
A computer-implemented method comprising: in response to at least a selection through a portable signing device by an employee of a courier service, presenting an electronic document through the portable signing device to a signer, the electronic document assigned to an item being delivered to the signer and configured to indicate receipt of the item by the signer, the portable signing device managed by the courier service different than the signer of the electronic document and configured to receive signatures from different signers; calculating a one-way hash for the electronic document; encrypting, using the portable signing device, the one-way hash using a private key assigned to the portable signing device different from private keys assigned to signers and inaccessible to signers, the portable device configured to encrypt, using the portable-device private key, one-way hashes for documents signed by other signers, a public-private key certificate of the private key is maintained by the courier service and inaccessible to the signers; embedding a digital watermark representing the encrypted one-way hash in a signature document, wherein the digital watermark is a second image representing a watermark that overlays at least a portion of a first image and embeds in the signature document the encrypted one-way hash calculated using the electronic document; based on input from the signer of the electronic document, altering an appearance of the signature document having the embedded digital watermark; and associating the electronic document with the signature document, wherein the electronic document and the signature document together comprise a signed electronic document.