3. The method claimed in claim 2 , further comprising verifying the document, wherein verifying the document comprises: scanning, by a scanning device of a verification system, the document having the printed identifier and gradient strip thereon to obtain an image of the document; obtaining, by a processing device of the verification system, contents of the identifier from the image including the gray scale profile; obtaining, by the processing device of the verification system, the area of interest of the document from the image; segmenting, by the processing device of the verification system, the area of interest obtained from the image into a plurality of elements; obtaining, by the processing device of the verification system, an average gray scale of each element in the area of interest obtained from the image; determining, by the processing device, a relative gray scale of each element in the area of interest obtained from the image by matching the average gray scale of each element of the area of interest to the closest element of the gradient strip; generating, by the processing device, a gray scale profile of the area of interest obtained from the image; comparing, by the processing device of the verification system, the gray scale profile of the area of interest obtained from the image with the corresponding gray scale profile that was inserted in the identifier; and determining, by the processing device of the verification system, if the gray scale profile of the area of interest obtained from the image deviates from the gray scale profile that was inserted into the identifier.
3. The method claimed in claim 2 , further comprising verifying the document, wherein verifying the document comprises: scanning, by a scanning device of a verification system, the document having the printed identifier and gradient strip thereon to obtain an image of the document; obtaining, by a processing device of the verification system, contents of the identifier from the image including the gray scale profile; obtaining, by the processing device of the verification system, the area of interest of the document from the image; segmenting, by the processing device of the verification system, the area of interest obtained from the image into a plurality of elements; obtaining, by the processing device of the verification system, an average gray scale of each element in the area of interest obtained from the image; determining, by the processing device, a relative gray scale of each element in the area of interest obtained from the image by matching the average gray scale of each element of the area of interest to the closest element of the gradient strip; generating, by the processing device, a gray scale profile of the area of interest obtained from the image; comparing, by the processing device of the verification system, the gray scale profile of the area of interest obtained from the image with the corresponding gray scale profile that was inserted in the identifier; and determining, by the processing device of the verification system, if the gray scale profile of the area of interest obtained from the image deviates from the gray scale profile that was inserted into the identifier. 6. The method claimed in claim 3 , further comprising: sending at least a portion of the identifier to a datacenter; and comparing the at least a portion of the identifier to previously used identifiers stored at the database to determine if the document has already been verified.