Abstract:
A method to secure unique information about a handwritten document and to provide verification of document&#39;s authenticity, integrity and non-repudiation. The method includes the following steps: creating a document having an area of interest containing information, segmenting the area of interest on the document into a plurality of elements, obtaining the average gray scale of each element, inserting the average gray scale of each element into an identifier, and attaching the identifier to the document.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates generally to the field of the preparation of prescriptions and more particularly to the preparation of secure medical prescriptions. 
       BACKGROUND OF THE INVENTION 
       [0002]    A prescription is a written document which contains directions for the preparation and administration of a remedy. Prescriptions originated at the beginning of history, when there were medications and a writing system to capture directions for their preparation and usage. 
         [0003]    Modern prescriptions evolved with the separation of the role of the pharmacists, lens maker, dental technician, etc. from that of the physician, optician, or dentist. A prescription may direct a pharmacist to mix or compound medications in the pharmacy for the specific needs of the patient, or direct a lens maker to prepare optical lenses having particular characteristics. Prescriptions may also be used by dentists to direct dental technicians to prepare crowns as directed. 
         [0004]    Pharmacists and physicians are regulated professions in most jurisdictions. A prescription as a communications mechanism between them is also regulated and is a legal document. Regulations may define what constitutes a prescription, the contents and format of the prescription. States may require that a prescription contain the following elements: the name or names and address of the patient or patients; the name and quantity of the drug or device prescribed and the directions for use; the date of issue of the prescription; the name, address, and telephone number of the prescriber, his or her license classification, and his or her federal registry number, if a controlled substance is prescribed; a legible, clear notice of the condition for which the drug is being prescribed, if requested by the patient or patients; and the signature of the prescriber issuing the order. 
         [0005]    Currently, prescriptions are written on stationary paper pads. Thus, one of the problems of the prior art is that it is difficult for the pharmacist to authenticate the signature of the prescriber on the prescription or to identify that the same prescription was not reused. 
         [0006]    Prescriptions are sometimes forged because someone may be a hypochondriac and a prescriber may not be willing to write a prescription for the hypochondriac. More often drug addicts, or drug pushers forge prescriptions for narcotics, because the narcotics may not be otherwise available, the narcotics are cheaper and safer as prescription drugs than as street drugs. Thus, an additional problem of the prior art is to reduce the amount of forged prescriptions. 
         [0007]    Another problem of the prior art is that the holder of a valid prescription may change some of the information on the prescription, i.e., change the dosage of the prescribed medication from 10 mg to 100 mg, etc. 
       SUMMARY OF THE INVENTION 
       [0008]    This invention overcomes the disadvantages of the prior art by enabling a pharmacist to authenticate and verify the integrity of a handwritten prescription or to prevent the use of the prescription more than once. The invention also enables the pharmacists to detect some fraudulently written prescriptions. The foregoing may be accomplished by applying a computer indicium to a prescriber&#39;s handwritten prescription. Thus, the pharmacy will have the means to verify that the indicium is valid and the indicium matches the prescriber shown on the prescription. 
         [0009]    It would be obvious to one skilled in the art that this invention may be used for documents other than prescriptions such as birth certificates, citizenship papers, baptismal certificates, licenses, deeds, stock certificates, car titles, medical records, passports, school transcripts and admission papers, purchase receipts, military discharge papers, baptismal and death certificates, marriage licenses, divorce papers, contracts, real estate assignments and related papers, insurance policies, banking and financial records, checks, intellectual property transfer agreements and patents, personnel records, court papers, warranties, income tax returns, accounts receivable files, invoices, wills, other legal documents, etc 
         [0010]    An advantage of the invention is that the pertinent information regarding the transaction, i.e., application of the indicium may be communicated to a data center. Thus, the pharmacy may verify with the data center that the prescription is not being replayed, meaning that the prescription was not previously filled and prevent the use of copies of the prescription. 
         [0011]    An additional advantage of this invention is the digital signature in the indicium will also prevent the prescriber&#39;s office from denying that the prescription was written by his office in cases where multiple prescriptions are written for narcotics or controlled substances. 
         [0012]    A still further advantage of this invention is that an area of interest on the prescription may be analyzed to determine if the prescription was modified. An additional advantage of this invention is that an area of interest on the prescription may be generated by a computer. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a drawing of a medical handwritten prescription; 
           [0014]      FIG. 2  is a block diagram of this invention; 
           [0015]      FIG. 3A  is a flowchart that describes the process to secure the handwritten prescription  11  for the purpose of authentication and to prevent replay; 
           [0016]      FIG. 3B  is a flowchart that describes the pharmacy&#39;s process to verify the authenticity and prevent the replay of the handwritten prescription  11 , when the pharmacy verifies the digital signature on the prescription; 
           [0017]      FIG. 3C  is a flowchart that describes the pharmacy&#39;s process to verify the authenticity and prevent the replay of the handwritten prescription  11 , when a data center verifies the digital signature on the prescription; 
           [0018]      FIG. 3D  is a flowchart that describes the data center&#39;s process to verify the authenticity and prevent replay of the handwritten prescription  11 , when a data center verifies the digital signature; 
           [0019]      FIG. 4  is a block diagram of an alternate embodiment of this invention; 
           [0020]      FIG. 5A  is a flowchart that describes an embodiment of the invention using perceptual hashing algorithm, specifically the process to secure the handwritten prescription  11  for the purpose of authentication, integrity and to prevent replay; 
           [0021]      FIG. 5B  is a flowchart that describes an embodiment of the invention using perceptual hashing algorithm, specifically the pharmacy&#39;s process to verify the handwritten prescription  11  authentication, integrity and to prevent replay; 
           [0022]      FIG. 6A  is a drawing of a prescription containing a reference strip, used in an embodiment of this invention using gray scale profile (GSP) algorithm; 
           [0023]      FIG. 6B  is a drawing of a prescription illustrating the segmentation of area of interest into elements, used in an embodiment of this invention using gray scale profile (GSP) algorithm; 
           [0024]      FIG. 6C  is a drawing of a prescription illustrating the assignment of gray levels for each element to the closest reference gray level found on the reference strip, used in an embodiment of this invention using gray scale profile (GSP) algorithm; 
           [0025]      FIG. 6D  is a drawing of a prescription illustrating the assignment of index numbers corresponding to the closest reference gray level, used in an embodiment of this invention using gray scale profile (GSP) algorithm; 
           [0026]      FIG. 6E  is a drawing of an altered prescription, used in an embodiment of this invention using gray scale profile (GSP) algorithm; 
           [0027]      FIG. 6F  is a drawing of an altered prescription illustrating the segmentation of area of interest into elements, used in an embodiment of this invention using gray scale profile (GSP) algorithm; 
           [0028]      FIG. 6G  is a drawing of an altered prescription illustrating the assignment of gray levels for each element to the closest reference gray level found on the reference strip, used in an embodiment of this invention using gray scale profile (GSP) algorithm; 
           [0029]      FIG. 6H  is a drawing of an altered prescription illustrating the assignment of index numbers corresponding to the closest reference gray level, used in an embodiment of this invention using gray scale profile (GSP) algorithm; 
           [0030]      FIG. 7  is a flowchart describing the gray scale profile (GSP) algorithm; 
           [0031]      FIG. 8A  is a flowchart that describes the process to secure the handwritten prescription  11  for the purpose of authentication, integrity and to prevent replay, used in an embodiment of this invention using gray scale profile (GSP) algorithm; and 
           [0032]      FIG. 8B  is a flowchart that describes the pharmacy&#39;s process to verify the handwritten prescription  11  authentication, integrity and to prevent replay, used in an embodiment of this invention using gray scale profile (GSP) algorithm. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0033]    Referring now to the drawings in detail and more particularly to  FIG. 1 , the reference character  11  represents a document that is a medical prescription. Prescription  11  indicates the name of the prescribing physician  12 , the license classification and license number  13  of the prescribing physician, the physician&#39;s address  14  and telephone number  15 . Prescription  11  also indicates the name of the patient, the patient&#39;s address  18  and the patient&#39;s age  17 . The date the prescription was written is shown in space  19 . The medication prescribed namely Zeita is shown at  20  and the dosage of the medication is indicated at  21 . Instructions&#39;, regarding the use of the Zeta is written in an abbreviated format at  22 . The abbreviated format indicates that the pharmacists should write on the label of the bottle containing Zeita (not shown), that the medication should be taken orally once a day. Space  23  indicates that 90 tablets should be supplied each time the prescription is filled and space  24  indicates that the prescription may be filed three times. The physician&#39;s signature appears in space  25  and an identification indicium or code  26  is placed on prescription  11 . Identification code  26  may be represented by printed alphanumeric characters, a linear bar code, a two-dimensional bar code, glyphs, information stored in an radio frequency identification device (RFID) attached to the prescription or otherwise attached to the prescription. Code  26  may be printed on prescription  11  with a black ink, colored ink, toner, invisible ink, black fluorescent ink, etc. or affixed to a label that is attached to prescription  11 . A black fluorescent ink is disclosed in the Auslander et al. U.S. Pat. No. 6,793,723 entitled “Homogeneous Photosensitive Optically Variable Ink Compositions For Ink Jet Printing” herein incorporated by reference. 
         [0034]    Code  26  includes a digital signature  27  of specified information. The digital signature does not hide the content of the information. The digital signature verifies the content of the information by authenticating someone who is in possession of the signing key for code  26 . Thus, the digital signature supports authentication and non-repudiation. Code  26  establishes that someone who signed the prescription had access to the prescription computer  9  ( FIG. 2 ) that was assigned to the medical office that issued the prescription and indicates that the prescription came from an indefinable user of the prescription computer  9 . Hence, the digital signature will also prevent the physicians&#39; office from denying that the prescription was written by his office. Code  26  may be encrypted to hide the information and prevent unauthorized disclosure. 
         [0035]    In one embodiment of the invention code  26  may include the serial number of the prescription computer that printed code  26 , the value of a counter which the prescription computer increments after each code  26  impression and the digital signature of the above. Thus, code  26  will be a unique identifier. 
         [0036]    In another embodiment of the invention in addition to the information contained in the aforementioned paragraph, the information covered by the digital signature for code  26  may also include the date and time when the code  26  was printed. 
         [0037]    Each page of prescription  11  may also have a unique identifier  29  printed on it. Unique identifier  29  is unique over a defined domain which can be as narrow as the batch of printed prescriptions  11  on individual pads, or as wide as a globally unique identifier. Unique identifiers are disclosed in the Pintsov U.S. Pat. No. 5,612,889 entitled “Mail Processing System With Unique Mailpiece Authorization Assigned In Advance Of Mailpieces Entering Carrier Service Mail Processing Stream”, herein incorporated by reference. Usually, to ensure uniqueness over a wider domain, the length of the identifier needs to be increased. 
         [0038]    When this invention uses a unique identifier  29  for each individual page of prescription  11 , identifier  29  is made available to computer  35  ( FIG. 2 ) which calculates the digital signature of the information obtained by concatenating several pieces of information which together make up the payload. This is referred to in block  107  of FIG.  5 A. The unique identifier  29  can be either entered manually into computer  35  ( FIG. 2 ), or entered using a scanner  82  ( FIG. 4 ) followed by Optical Character Recognition (OCR), calculated in sequence based on a simple protocol of incrementing the previous number or using a barcode scanner (not shown). 
         [0039]    The verification steps of the unique identifier  29  are shown in  FIG. 5B , step  168  where the unique identifier  29  is retrieved from the payload and in step  170  it is compared with the identifier printed on the prescription  11  presented to the pharmacy. The foregoing process may also be used to verify that the code  26  matches the prescription to which it is affixed. 
         [0040]      FIG. 2  is a block diagram of an embodiment of this invention. This embodiment provides for the verification of the authenticity and non-repudiation of the document. Secure device  9  contains prescription computer  35 , bar code printer  36  and cryptographic keys  37 . Device  9  insures that printer  36  is used only under the control of computer  35  and each instance of printing code  26  contains a unique identifier and a digital signature. Prescription computer  35  may be used to generate code  26  digitally signed using keys  37 , to print code  26  on prescription  11  utilizing printer  36  or any other marking device. After barcode reader  40  or other reading device scans code  26 , information contained in code  26  may be sent from computer  38  to data center computer  41  and stored in data center data base  42 . The information may be a unique identifier of secure device  9 , for example the serial number of computer  35 , the value of a counter within computer  35 , which increments after each impression of code  26  and the digital signature of the above. The manner in which code  26  and the digital signature is obtained will be described in the description of  FIG. 3A . 
         [0041]    The patient for whom prescription  11  was written or their designee will take prescription  11  to a pharmacy, where bar code  26  of prescription  11  will be scanned and transmitted to pharmacy computer  38 . The digital signature  27  included in code  26  may be verified by applying the appropriate cryptographic algorithms either by the pharmacy&#39;s computer  38  using keys  39  or by computer  41  using keys  43 . The manner in which code  26  and the digital signature is verified will be described in the description of  FIG. 3B  when pharmacy computer  38  verifies the digital signature and in the description of  FIG. 3C  when data center computer  41  verifies the digital signature. As a result the pharmacy will be assured that the serial number of prescription computer  35  that printed code  26 , and the value of a counter which prescription computer  35  increments after each code  26  impression came from a trusted source, i.e., the prescription computer  35 . 
         [0042]    The cryptographic algorithms for digital signatures used to implement this invention include, but are not limited to, public key cryptography (for example: RSA algorithms, elliptic curves algorithms), symmetric key, etc. 
         [0043]    Computer  38  will transmit the record that indicates the prescription identified by code  26  has been used at a given pharmacy to data center computer  41 . The foregoing prevents reuse of prescription  11 , at a later time in the same or different pharmacy. 
         [0044]      FIG. 3A  is a flow chart that describes the process to secure the hand written prescription  11  using only authentication. The process begins at step  200 , where a physician writes prescription  11  by hand on an ordinary prescription pad. Step  201  concatenates the unique identifiers of prescription computer  35 , i.e., time/date, the count number of a counter in computer  35 , the physician&#39;s identification etc. to create an information payload. Next in step  202  prescription computer  35  digitally signs the information payload using the assigned cryptographic key found in keys  37 . Now, in step  203  the information payload is attached to the prescription  11  by printing barcode  26 , which may be a one or two dimensional on prescription  11 . The information payload may also be programmed into a radio frequency identification device (RFID) attached to prescription  11 . 
         [0045]      FIG. 3B  is a flow chart that describes the process which takes place in a pharmacy to verify the authenticity and validity of the handwritten prescription  11 , when the pharmacy verifies the digital signature on the prescription and uses a trusted third party (TTP) datacenter to determine if the prescription can be accepted. The datacenter in most cases is a remote, distinct, facility, but it can be understood that in the most trivial case, the datacenter can be a computer system located in the pharmacy. The process begins in step  205 , where barcode reader  40  scans barcode  26  on prescription  11  and applies any needed redundancy in order to retrieve the content of barcode  26 . Next, in step  206  barcode reader  40  transfers the content of barcode  26  to computer  38 . Then in step  207  the digital signature of the payload is verified by computer  38 . At this point step  208  determines whether or not the digital signature is valid. If step  208  determines that the digital signature is not valid step  209  will indicate that verification has failed and there is something wrong with prescription  11 . If step  208  verifies that the digital signature is fine then step  210  will extract prescription  11  identifiers (P ID ) from the payload i.e., identification of computer  35 , time/date, the value of a counter in computer  35  that is contained in barcode  26 , the physician&#39;s identification, etc. Next in step  211  computer  38  requests from data center computer  41  confirmation that this (P ID ) can be accepted. Step  212  determines whether or not (P ID ) can or cannot be accepted. If step  212  determines that (P ID ) can not be accepted then in that event step  213  will indicate that verification has failed and there is something wrong with prescription  11 . If step  212  determines that (P ID ) may be accepted then step  214  will indicate that verification has succeeded. 
         [0046]      FIG. 3C  is a flow chart that describes the process which takes place in a pharmacy to verify the authenticity and validity of a hand written prescription  11 , when a data center is used to verify both the digital signature on the prescription  11  and the fact the prescription can be used. The process begins in step  220  where barcode reader  40  reads and decodes barcode  26  and applies any redundancy as needed in order to retrieve the content of barcode  26 . Then in step  221  barcode reader  40  transfers the content of barcode  26  to computer  38 . Now in step  222  computer  38  transmits the content of barcode  26  to data center computer  41 . Then in step  223  pharmacy computer  38  receives the verification results of barcode  26  from data center computer  41 . Then step  224  indicates that the verification results have been completed. 
         [0047]      FIG. 3D  is a flow chart that describes the process which takes place in a datacenter to verify the authenticity and validity of the hand written prescription  11 , when a data center verifies the digital signature and validity on the prescription. The process begins in step  230  where data center computer  41  receives the content of barcode  26  from pharmacy computer  38 . Then in step  231  data center computer  41  calculates the digital signature on the payload. Next step  232  determines whether or not the digital signature is verified. If step  232  determines that the digital signature is not verified then step  233  will indicate that verification has failed. The indication that verification has failed will be sent to step  239  so that a response may be transmitted to pharmacy computer  38 . If step  232  determines that the digital signature is fine then the next step will be step  234 . In step  234  data center computer  41  extracts prescription identifiers (P ID ) from the payload created by computer  35  i.e., identification of computer  35 , time/date, the number printed by a counter contained in prescription computer  35 , the physician&#39;s identification, etc. Next, in step  235  data center computer  41  checks to see if this (P ID ) can be accepted. Then step  236  determines whether or not (P ID ) may or may not be accepted. If step  236  determines that (P ID ) cannot be accepted then step  237  will indicate that verification has failed. The criteria for accepting the payload is given by the rules of the application, for example, a prescription cannot be used beyond the number of refills allowed. It is understood that the pharmacy may transmit to the datacenter, along with the content of code  26 , additional information (for example refill count as written on the prescription) to support such decisions. Step  239  will then transmit a response to pharmacy computer  38  indicating that verification has failed. If step  236  determines that (P ID ) is accepted then step  238  will indicate that verification has succeeded. Now an indication of the successful verification will be sent in step  239  to pharmacy computer  38 . 
         [0048]      FIGS. 4 ,  5 A and  5 B illustrate an alternate embodiment of this invention which uses an algorithm based on the perceptual hash of portions of a document. This embodiment provides for the verification of the authenticity, integrity and non-repudiation of the document. The perceptual hash of an image is a string of binary data which changes significantly when the image from which it was calculated changes in a way that would be noticeable for a human observer, but it changes very little due to variations of the image typically associated with scanning noise, variation due to skew, scale, luminosity, etc. An example of perceptual hash algorithm is contained in a communication from M. Kivanc Mihcak and Ramarathnam Venkatesan titled “New Iterative Geometric Methods for Robust Perceptual Image Hashing” which may be found at http://research.microsoft.com/˜kivancm/publications/spdrm01-pr.ppt, herein incorporated by reference. 
         [0049]      FIG. 4  is a block diagram of an alternate embodiment of this invention. Secure device  8  contains prescription computer  7 , bar code printer  81  and secure storage for cryptographic keys  80 . Device  8  insures that printer  81  is used only under the control of computer  7  and each instance of printing code  26  contains a unique identifier (for example, the value of an imprint counter) and a digital signature. Computer  7  may be used to generate code  26  using keys  80  and to print code  26  on prescription  11  utilizing printer  81  or any other marking device for example a RFID programming device. In this embodiment, the prescription  11  is scanned by scanner  82 . The resulting image file is sent to computer  75 . Computer  75  identifies the areas of interest on the prescription image, for example area of interest  640  in  FIG. 6A , which contains the handwritten text of the prescribed medication (It is understood that the same method is applicable to printed prescriptions). Computer  75  applies a perceptual hashing algorithm to the image of the area of interest identified previously, resulting in a perceptual image hash. Alternatively, computer  75  may calculate the Gray Scale Profile (GSP) using the algorithm described in  FIG. 7 . The perceptual image hash (alternatively GSP) is then sent to the computer  7  which is part of the secure device  8 . Computer  7  concatenates several pieces of information (for example: the perceptual image hash (alternatively GSP), secure device ID, value of print counter, etc.) resulting in the information payload to be attached to the prescription  11 . Additionally, computer  7  calculates a digital signature of the information payload using the encryption keys stored in the secure storage  80 . Then, computer  7  generates the information to be attached to the prescription, for example by printing a barcode  26 , or by programming a RFID device. This information contains the payload and the digital signature  27  ( FIG. 1 ). 
         [0050]    In this embodiment, the prescription  11  is taken to the pharmacy to be filled. The pharmacy wants to verify that the prescription comes from a known prescriber, also the pharmacy wants to know that the content of the prescription  11  was not altered, in particular the area of interest  640  which contains the prescribed items, and lastly, the pharmacy wants to know that the prescription was not used more than the permitted number of times in the same or other pharmacies. At the pharmacy, the prescription  11  is scanned by the scanner  78 . The resulting image is sent from the scanner  78  to the computer  79 . The computer  79  uses the process described in  FIG. 5B  to verify the digital signature on computer  79  using keys  83 , thus identifying the secure device  8  used by the prescriber to secure the prescription  11 . 
         [0051]    The computer  79  extracts from code  26  information which uniquely identifies the prescription  11 , for example the ID of secure device  8  and the print counter in computer  7 . Additional information may be sent from the pharmacy to the datacenter, for example the number of refills allowed. This information may be sent from computer  79  to data center computer  76  and compared with information stored in data center data base  77 . The result of this comparison is sent back to the computer  79  to inform the pharmacy if the prescription may be filled or not. Also, this information may be stored in the database  77  for further use. The manner in which code  26  and the digital signature is created and used are described in  FIG. 5A  and  FIG. 5B . 
         [0052]    Alternatively, the verification of the digital signature can be performed in a datacenter. In this case, the patient for whom prescription  11  was written or their designee will take prescription  11  to pharmacy scanner  78 , where the contents of prescription  11  will be scanned and transmitted to pharmacy computer  79 . Computer  79  sends code  26 , either as an image or as alphanumeric information to datacenter&#39;s computer  76 . Computer  76  may use keys  85  to verify the digital signature of code  26  by applying the appropriate cryptographic algorithm. As a result the pharmacy will be assured that the serial number of computer  7  that printed code  26 , and the value of a counter which computer  7  increments after each code  26  impression came from a trusted source. This approach eliminates the need to maintain secure cryptographic key storage  83  in each pharmacy, and instead uses the datacenter computer  76  and secure cryptographic key storage  85  to ensure the authenticity of the code  26 . 
         [0053]    Computer  79  will transmit the record that indicates the prescription identified by code  26  has been used at a given pharmacy to data center computer  76 . The foregoing prevents reuse of prescription  11 , at a later time in the same or different pharmacy. 
         [0054]      FIG. 5A  is a flow chart that describes the process which takes place in the prescriber&#39;s office to secure the handwritten prescription  11  integrity and authentication. The process begins at step  101 , where the physician writes prescription  11  by hand on an ordinary prescription pad. Now the process goes to step  102 , where scanner  82  scans prescription  11 . Then, in step  102 , the image file is transferred to computer  75 . 
         [0055]    At this point, the process goes to step  104  where areas of interest on prescription  11  are located, i.e., patient information, the medication prescribed, signature, etc. Then, in step  105 , an image file is created for the areas of interest. 
         [0056]    Next, in step  106 , a perceptual hashing algorithm is used to obtain an image hash. Perceptual hashing of an area of interest may be used to ensure the integrity of the area of interest (for example prescription content  640 ). Ensuring the integrity of an area of interest means verifying that the area of interest was not altered between the time code  26  was attached to the prescription and the time code  26  was processed by the pharmacy&#39;s computer  79 . Integrity of a document (for example a prescription) is always an important issue as long as the document may be in the possession of parties that cannot be trusted (in this case a patient cannot be trusted by the doctor or pharmacy not to modify the prescription). In the context of cryptography, the integrity of the data is provided by cryptographic hash functions (MD5, SHA-1) in which the data is mapped to short bit strings that make up the hash value, which is then attached to the data. Whenever one would like to test the integrity of the data, one recalculates the hash value from the data itself and compares it to the attached hash value. 
         [0057]    Step  107  concatenates the image hash with unique identifiers (identification of computer  7 , time/date, the count in the imprint counter in computer  7 , prescription  11  identifications, etc.) to create an information payload. Then, step  108  digitally signs the information payload using the assigned cryptographic key from keys  80 . Now, in step  109 , the information payload is attached to the prescription  11  by printing a barcode  26  on prescription  11 . The barcode may be one- or two-dimensional. The information payload may also be programmed into a radio frequency identification device (RFID) attached to prescription  11 . 
         [0058]      FIG. 5B  is a flowchart that describes the process which takes place at the pharmacy to verify the integrity and authenticity of handwritten prescription  11 . The process begins in step  150 , where scanner  78  scans prescription  11 . Next, in step  151 , the image file is transferred to computer  79 . Then, in step  152 , areas of interest on prescription  11 , i.e. area of interest  640  which contains the medication prescribed, other areas of interest containing patient information, signature, etc., are located. Then, in step  153 , an image file for the areas of interest is created. Then in step  154 , a perceptual hashing algorithm is applied (for example to area of interest  640 ) to obtain an image hash (H L ). 
         [0059]    In step  156 , the areas of interest which contains barcode  26  is located. Then, in step  157 , the process reads and decodes the barcode  26 , applying any redundancy if needed. Next, in step  159 , the digital signature of the information payload is verified. 
         [0060]    Step  160  determines whether or not the digital signature is valid. If step  160  determines that the digital signature is not valid, the process goes to step  161 , which indicates that verification has failed and there is something wrong with prescription  11 . If step  160  determines that the digital signature is correct, the next step in the process will be step  162 , where the image hash is extracted from the information payload (H p ). 
         [0061]    After steps  154  and  162  are completed, step  155  will calculate the distance D between in the perceptual hash of the image calculated locally (H L ) and the perceptual hash of the image calculated in the prescriber&#39;s office and found in the information payload (H p ). The distance D between (H L ) and (H p ) is obtained by utilizing the method described in the Arun Qamra, et. al article entitled “Enhanced Perceptual Distance Functions And Indexing For Image Replica Recognition”, published in the March 2005, issue of IEEE Transactions On Pattern Analysis And Machine Intelligence, Vol. 27, No. 3, herein incorporated by reference. 
         [0062]    Then in step  165 , the process will compare the distance D with the acceptable threshold T. An acceptable threshold is empirically determined by the application in which it is used. Then, in step  166 , the process will determine whether or not the distance D is less than or equal to the acceptable threshold T. If step  166  determines that the distance D is not less than or equal to the acceptable threshold T, step  167  indicates that the verification has failed and there is something wrong with prescription  11 , most likely the prescription was altered. 
         [0063]    If step  166  determines that the distance D is less than or equal or equal to the acceptable threshold T, the next step is step  168 , where prescription identifiers (P ID ) from the information payload (device identification, the time/date, imprint counter, physician&#39;s identification, etc.) are extracted. 
         [0064]    At this point in process, step  169  requests from data center computer  76  confirmation that this (P ID ) can be accepted. Then, step  170  determines whether or not P ID  may or may not be accepted. If step  170  determines that P ID  cannot be accepted, step  171  will indicate that the verification has failed and there is something wrong with prescription  11 . If step  170  indicates that (P ID ) is accepted, then step  172  will indicate that the verification is successful and prescription  11  is a valid prescription. 
         [0065]      FIGS. 4 ,  6 A,  6 B,  6 C,  6 D,  6 E,  6 F,  6 G,  6 H,  7 ,  8 A and  8 B illustrate another embodiment of this invention which uses an algorithm based on the gray scale profile of portions of a document instead of the perceptual hash of an image which was described previously. This embodiment provides for the verification of the authenticity, integrity and non-repudiation of the document. 
         [0066]      FIG. 6A  is a drawing of prescription  11  of  FIG. 1  containing reference gradient strip  28  and an area of interest  640 . Gradient strip  28  contains four tone levels  631 ,  632 ,  633  and  634 . Levels  631 ,  632 ,  633  and  634  have varying proportions of white and black, to give a full range of grays between white and black. Gradient strip  28  may be divided into additional levels to represent different levels of gray. Area of interest  640  has a length equal to L and a height equal to H. Area  640  contains information regarding the medication prescribed by Physician Gold, namely the medication Zeita its dosage instructions regarding the use of the Zeita and 90 tablets should be supplied each time the prescription is filled. It would be obvious to one skilled in the art that additional areas of interest may be used, i.e., areas representing information regarding the patient, areas representing the physician&#39;s signature, areas representing the number of refills, etc. 
         [0067]      FIG. 6B  is a drawing of prescription  11  illustrating the segmentation of area of interest  640  into elements. Area of interest  640  is divided into N×M sub-sections or elements. N and M are the number of columns and rows, respectively. In  FIG. 6B , N=8 and M=4. No material appears in element  641  and the letters “Z, e, i ” and a portion of the letter “t” appears in element  642 . Portions of the “#” sign and portions of the numerals “9 and 0” appear in element  643 . Portions of the numeral “0” appear in element  644 . 
         [0068]      FIG. 6C  is a drawing of prescription  11  illustrating the assignment of gray levels for each element to the closest reference gray level found on the gradient strip  28 . Element  651  appears to have the tone shown in level  631  and element  652  appears to have the tone shown in level  633 . Element  653  appears to have the tone shown in level  633  and element  654  appears to have the tone shown in level  631 . 
         [0069]      FIG. 6D  is a drawing of prescription  11  illustrating the assignment of index numbers corresponding to the closest reference gray levels appearing in gradient strip  28 . Level  631  is assigned index number “0’ and level  632  is assigned index number “1”. Level  633  is assigned index number “2’ and level  634  is assigned index number “3”; It would be obvious to one skilled in the art that additional index numbers may be used when there are additional gray scale levels appearing in strip  28 . Element  661  has the index number indicated by level  631  and element  662  has the index number indicated by level  633 . Element  663  has the index number indicated by level  633  and element  664  has the index number indicated by level  631   
         [0070]      FIG. 6E  is a drawing of an altered version of prescription  11 . Note in area of interest  640 , the number of tablets prescribed has been increased from ‘90” to “900”. 
         [0071]      FIG. 6F  is a drawing of an altered version of prescription  11  illustrating the segmentation of area of interest  640  into elements  671 ,  672 ,  673  and  674 . No material appears in element  671  and the letters “Z, e, i” and a portion of the letter “t” appears in element  672 . Portions of the “#” sign and portions of the numerals “9 and 0” appear in element  673 . Portions of the added numeral “0” and almost the complete numeral “0” appear in element  674 . 
         [0072]      FIG. 6G  is a drawing of an altered prescription  11  illustrating the assignment of gray levels for each element to the closest reference gray level found on the reference gradient strip  28 . Element  681  appears to have the tone shown in level  631  and element  682  appears to have the tone shown in level  633 . Element  683  appears to have the tone shown in level  633  and element  684  appears to have the tone shown in level  632 . Note in  FIG. 6C  element  654  had the tone shown in level  631 . 
         [0073]      FIG. 6H  is a drawing of an altered prescription  11  illustrating the assignment of index numbers corresponding to the closest reference gray level appearing in gradient strip  28 . Element  691  has the index number indicated by level  631  and element  692  has the index number indicated by level  633 . Element  693  has the index number indicated by level  633  and element  694  has the index number indicated by level  633 . Note in  FIG. 6D  element  664  had a “0” which indicates the index number of level  631  and now element  694  has a “1” which indicates the index number of level  632 . Thus, this is an indication that the prescription  11  has been altered. 
         [0074]      FIG. 7  is a flowchart that describes the grey scale profile (GSP) algorithm. The GSP algorithm receives as input an image (of the area of interest), the number of rows and the number of columns. The algorithm divides the image into N×M elements and produces as output a set of numbers that are indexes into an array of gray levels, one number for each element of the area of interest. 
         [0075]    The process begins in step  650  where the image file for the areas where changes need to be detected on prescription  11  i.e., the prescription area  29 , the patient&#39;s name, area, etc. Then in step  652  the image from area  29  is divided into N×M subsections “elements”, where N and M are the number of columns and rows. Next in step  654  the average grey level for each area of interest for each element is calculated. Then in step  656  the relative grey level R for each element in the area of interest is calculated. 
         [0076]    In step  660  an image file of the reference grey scale strip is received. In step  662  the number of elements of the reference strip is obtained. In  FIG. 6A  the number of elements is four. S is the number of elements in the reference strip (S=4 in  FIG. 6A ). Then in step  664  the average grey level for each reference strip element is calculated. Next in step  666  the relative grey level R for each element of the reference strip is calculated. In step  668  each grey level R has an index based on the position of the element in the referenced strip: first one is a zero, the second one is a one, etc. In  FIG. 6A , the index of element  631  is 0, the index of element  632  is 1, the index of element  633  is 2 and the index of element  634  is 03. 
         [0077]    After steps  656  and  668  are completed, step  670  will for each element in the area of interest, find the closest relative grey level in the reference strip. Next step  672  will use the indices of the closest grey level in the reference strip, to build the grey scale profile of the area of interest. 
         [0078]    The aforementioned flowchart may be expressed mathematically by the following Gray Scale Profile algorithm. 
         [0079]    The Gray Scale Profile (GSP) algorithm receives as input an image (of the area of interest  640 ), the number of rows “N” and the number of columns “M” and produces as output a set of numbers that are indexes into an array of gray levels, one number for each element of the area of interest. 
         [0080]    The algorithm receives an image file for the area where changes need to be detected (e.g. prescription area, patient name area, number of refills, etc. . . .). Assume that the area of interest is rectangular. If it is not rectangular, the algorithm can be modified to create sub-sections of other shapes, but the general idea can be maintained. 
         [0081]    The dimensions of the area of interest are L and H, length and height, respectively. 
         [0082]    The next step is to divide the image into N×M sub-sections (elements). N and M are the number of columns and rows, respectively. In  FIG. 6B , N=8 and M=4. 
         [0083]    The scanning resolution is R, measured in dots per inch. For simplicity, we can assume that the horizontal resolution is the same with the vertical resolution. The scanner and scanning software subsystem creates an image with 2 B  gray levels. Thus, each pixel is represented by a number P using B bits. P takes values between 0 and (2 B −1). For example, in an image using 2 bits per pixel, the darkest pixel (black) will be (0, 0) and the lightest pixel (white) will be (1, 1). For black, P=0 and for white P=3. 
         [0084]    Each scanned pixel has a P value as described above. Within a given element, we use the notation Pij for the value corresponding to the pixel on row i and column j. 
         [0085]    The number of pixels in each element is ((L/N)*R)×((H/M)*R). For example, if R=100 dpi, L=4 inches, H=2 inches and we chose to have 8 columns (N=8) and 4 rows (M=4), then each elements&#39; dimensions in pixels are (UN)*R=4/8*100=50 pixels horizontally, and (H/M)*R=2/4*100=50 pixels vertically. In this example, each element is a square 50 by 50 pixels. 
         [0086]    We define the average gray level (A) for an element to be the number obtained by calculating the sum of the P numbers for all pixels in the given element and dividing by the number of pixels. 
         [0000]    
       
         
           
             
               A 
               element 
             
             = 
             
               
                 
                   ∑ 
                   
                     i 
                     = 
                     1 
                   
                   
                     
                       L 
                       N 
                     
                     * 
                     R 
                   
                 
                  
                 
                   
                     ∑ 
                     
                       j 
                       = 
                       1 
                     
                     
                       
                         H 
                         M 
                       
                       * 
                       R 
                     
                   
                    
                   Pij 
                 
               
               
                 
                   ( 
                   
                     
                       L 
                       N 
                     
                     * 
                     R 
                   
                   ) 
                 
                 * 
                 
                   ( 
                   
                     
                       H 
                       M 
                     
                     * 
                     R 
                   
                   ) 
                 
               
             
           
         
       
     
       Hence, the A element  is a number between 0 and 2 B −1. 
       [0087]    The relative gray level R (expressed in percentages) is: 
         [0000]    
       
         
           
             
               R 
               element 
             
             = 
             
               
                 A 
                 
                   2 
                   B 
                 
               
               * 
               100 
             
           
         
       
     
         [0088]    The algorithms uses a strip containing reference gray levels ( 28  in  FIG. 6A ), which was previously applied/printed on the document. This strip is a set of rectangular elements printed such that they have their R numbers spaced equally between 0 and 100%. Each element of the strip is assigned a sequence number from 0 to 2 B −1. In  FIG. 1 , B=2, resulting in four elements numbered 0, 1, 2, and 3. The values of R for each of these elements is in the middle of each interval. For example, in  FIG. 1 , the strip  28  has four elements that are intended to generate the following R numbers: R 0 =12.5%, R 1 =37.5%, R 2 =62.5% and R 3 =87.5%. These values are selected in the middle of the four intervals corresponding to 0-25%, 25%-50%, 50%-75% and 75%-100%. We will refer to these number as ‘theoretical’ values of R. 
         [0089]    The reference gray levels are used to limit the variability introduced by printing and scanning devices and to ensure a consistent measurement of relative intensity of each element in the area of interest, for example where the prescription is written. 
         [0090]    Next step is to scan the reference strip under the same conditions used to scan the area of interest. This is best achieved by scanning the entire document and isolating the areas or interest as portions of the scanned image. Identify the number of elements S of the reference strip. In the above example S=4. 
         [0091]    For each image of an element in the reference strip ( 28 ) we calculate R element . Due to the variability of printing and scanning devices, the actual R numbers obtained may be different from the theoretical values. We will refer to these values as reference R numbers R element   reference . In the above example illustrated in  FIG. 6A , there are four elements or levels in the reference strip ( 631 ,  632 ,  633 ,  634 ) and their R values are:
       R 0   reference , R 1   reference , R 2   reference , and R 3   reference  
 
for each element in the area of interest  640  we calculate R element  and find the closest R reference  number. We then assign to the given element the index of the closest R reference  number.  FIG. 6D  illustrates the result of assigning the index number of the closest reference gray level. For example the element  661  in the upper left corner of the area of interest  640  is assigned gray level  0 , while the element  662  immediately to its right is assigned gray level  2 , as shown in  FIG. 6D  By simply looking at the amount of text which is covered by each of these two elements, one can notice that the first element has no writing in it (hence its gray level  0 ) and the second element contains the first four letters of the drug being prescribed (“Zeit”), hence the level is 2.
       
 
         [0093]    As a result of the assignment in previous step, a N×M array of numbers is generated, as shown in  FIG. 6D . This array is the Gray Scale Profile for the given area of interest and it is the output of the algorithm. 
         [0094]    The distance between two gray scale profiles, for example, the first GSP being obtained by processing the image scanned in the prescriber&#39;s office and the second GSP being obtained by processing the image scanned at the pharmacy can be computed as follows. 
         [0095]    The gray scale profile can be expressed as an array of numbers. For a two-dimensional array, the elements of a first array are expressed as: 
         [0000]      Uij 
         [0096]    Two GSP can be compared if they generate profiles of the same dimensions. If the elements of a second array are 
         [0000]      Vij 
         [0000]    than, the distance between the first array and the second array can be expressed by: 
         [0000]    
       
         
           
             D 
             = 
             
               
                 ∑ 
                 
                   i 
                   , 
                   j 
                 
               
                
               
                  
                 
                   Uij 
                   - 
                   Vij 
                 
                  
               
             
           
         
       
     
       Many other measures of this distance are available and practical considerations may dictate which is most appropriate. 
       [0097]      FIG. 8  A is a flow chart that describes the process to secure the hand written prescription  11  to the purpose of authentication, integrity and to prevent unauthorized use, including the grey scale profile algorithm. The process begins at step  301  where the physician writes prescription  11  by hand on a prescription pad. In step  302  a gradient strip  28  containing reference gray levels is applied to prescription  11 . Then in step  303  scanner  82  scans prescription  11 . Then in step  304  scanner  82  transfers the image file to computer  75 . At this point in step  305  areas of interest on prescription  11  are located, i.e., the specifics of the prescription, patient information, the physician&#39;s signature, etc. Next in step  306  an image file is created for the areas of interest. Step  307  applies the grey scale profile algorithm to generate a grey scale profile for the image of the areas of interest, i.e., the area that describes the prescribed medication. 
         [0098]    Step  308  concatenates the grey scale profile  28  with unique identifiers, i.e., the identification of the computer, the time/date, the value of a counter which computer  7  increments after each code  26  impression came from a trusted source, the identification of the physician who wrote prescription  11 , etc. to create an information payload. Step  309  then digitally signs the information payload using the assigned cryptographic keys  80 . Now, in step  310 , the information payload is attached to the prescription  11  by printing barcode  26 , which may be one or two dimensional on prescription  11 . The information payload may also be programmed into a Radio Frequency Identification Device “RFID” attached to prescription  11 . 
         [0099]      FIG. 8B  is a flow chart that describes the pharmacy&#39;s process to verify the handwritten prescription  11  authentication, integrity and to unauthorized use, including the GSP algorithm. The process begins in step  550  where scanner  78  scans prescription  11  to obtain relevant information from prescription  11 , i.e., patient information, the physician&#39;s signature, barcode  26 . Then in step  551  scanner  78  transfers the image file to computer  79 . Next in step  552  the areas of interest on prescription  11  are located i.e., patient information, the physician&#39;s signature. Next in step  553  an image file is created for the areas of interest. Then step  554  uses the grey scale profile algorithm to calculate the scanned grey scale profile. 
         [0100]    After steps  554  and  562  are completed, step  555  will calculate the distance D between the gray scale profile of the image scanned in the pharmacy (GSP scan ) and gray scale profile of the image scanned in the prescriber&#39;s office and received in the code  26  (GSP received ). 
         [0101]    The distance D may be calculated by Comparing corresponding points of the two profiles, as described in a subsequent paragraph. In step  565 , the process will compare the distance D with the acceptable threshold T. An acceptable threshold is empirically determined by the application in which it is used. Then, in step  566 , the process will determine whether or not the distance D is less than or equal to the acceptable threshold T. If step  666  determines that the distance D is not less than or equal to the acceptable threshold T, step  567  indicates that the verification has failed and there is something wrong with area of interest  640 . 
         [0102]    If step  566  determines that the distance D is less than or equal or equal to the acceptable threshold T, the next step is step  568 , where prescription identifiers (P ID ) from the information payload (device identification, the time/date, imprint counter, physician&#39;s identification, etc.) are extracted. 
         [0103]    At this point in the process, step  569  requests from data center computer  76  confirmation that this (P ID ) can be accepted. Then, step  570  determines whether or not P ID  may or may not be accepted. If step  670  determines that P ID  cannot be accepted, step  571  will indicate that the verification has failed and there is something wrong with area of interest  640 . If step  670  indicates that (P ID ) is accepted, then step  672  will indicate that the verification is successful and area  640  is genuine. 
         [0104]    The above specification describes a new and improved method for the preparation and securing of prescriptions. It is realized that the above description may indicate to those skilled in the art additional ways in which the principles of this invention may be used without departing from the spirit. Therefore, it is intended that this invention be limited only by the scope of the appended claims.