a standard operating system facility for making the identifications id1 id2 and id3 is the object linking and embedding ole standard for the windows u2122 operating system the character data display logic 235 uses the identification id1 of the certification logic block 245 for confirming that the first signature 269 accurately verifies the non certificate character data block 249 the human user can cause the character data display logic 235 to do this by selecting the bitmapped signature image 207 using either the keyboard 250 or the mouse 222 when the bitmapped signature image 207 is selected character data display logic 235 invokes the certification logic 245 on the first signature block 269 and character data block 249 the certification logic 245 then generates a signature using a hash function decrypts the first signature block 269 using a public key and compares the newly generated signature with the decrypted signature if the signatures match then first signature block 269 is verified in fig2 b a second certificate 255 is added to the data block 247 the second certificate 255 comprises a second dynamic link block 267 and a second signature block 271 the second dynamic link block 267 comprises an identification id4 of the data which the second certificate block 255 certifies in this example the identification id4 may indicate the non certificate character data block 249 the first certificate 253 or a combination of both the second dynamic link block 267 also contains.