Changes between Version 8 and Version 9 of security/electronic_signatures

Timestamp:

Feb 28, 2013, 6:28:09 PM (12 years ago)

Author:

Sam Habiel

Comment:

--

security/electronic_signatures

@@ -283 +283 @@
 I didn't write example code for Radiology/Nuclear Medicine as I don't have test data in that package.
 
+Once the new algorithm is in use, to reuse an example presented above, here is what to expect if the document is tampered with:
+Original Signature:
+{{{
+/es/ DOCTOR MCDUCK, MD
+ENT PHYSICIAN
+Signed: 02/27/2013 09:34
+}}}
+
+After tampering with the document
+{{{
+/es/ bad decrypt
+bad decrypt
+Signed: 02/27/2013 09:34
+}}}
+
+
 == Impact on the rest of VISTA ==
 Analysis of the impact will take two phases: That of the Hash and that of the change in encryption.
@@ -371 +387 @@
 Casting these issues aside, there is one way in which encryption can be strengthened: basing it on a hardware token. You will need one of these for each server, but this ensures that the encrypted data will be unreadable outside the machine at which it was encrypted.
 
-It's best to know what attack vectors to protect against. The biggest security risks are internal. External protection of the entire database can be done using full database encryption.
+It's best to know what attack vectors to protect against. The encryption system here is not designed to hide the data; rather only detect if it has been tampered with outside of the official APIs.
 
 = Appendix 1: How does TIU encrypt the signature blocks =
+TIU encrypts these fields in file TIU DOCUMENT (#8925)
+{{{
+1503 SIGNATURE BLOCK NAME
+1504 SIGNATURE BLOCK TITLE
+1509 COSIGNATURE BLOCK NAME
+1510 COSIGNATURE BLOCK TITLE
+}}}
+
+The encryption and decryption are done seamlessly in Fileman. Because of that, an end user and even an API programmer will not even detect that it exists.
+
+The input transform for each field is responsible for the encryption. It looks like this:
+{{{
+S X=$$ENCRYPT^TIULC1(X,1,$$CHKSUM^TIULC("^TIU(8925,"_+DA_",""TEXT"")")) K:$L(X)>120!($L(X)<3) X
+}}}
+
+The output transform for each field is responsible for decryption. It looks like this:
+{{{
+S Y=$$DECRYPT^TIULC1(Y,1,$$CHKSUM^TIULC("^TIU(8925,"_$S(+$G(DA):+DA,+$G(D0):+D0,1:"")_",""TEXT"")"))
+}}}
+
+The algorithm is simple: Encrypt and decrypt based on a vector of the checksum of the text. If the text changes, the originally computed encrypted string won't be decrypted successfully.