KRA - VAT - Electronic Digital Signing of Computer based issuing of Recorsd

General Procedure Description

The issuer of the record (ie invoice, consignment note, Invoice, Consignment Note, etc.) should possess:-

A special secure fiscal mechanism - Special Secure Fiscal Device or Record Signing (SSFDRS)
A computer with the appropriate software and capability of communicating with the SSFDRS.

The general manner of printing . issuing of records does not change and can be continued with the already existing infrastructure and printing mechanism of the issuer.

After entering and formatting the data to be printed in the computer, and after initialisation of the record issuing . printing, the computer's software saves, communicates and transmits to the SSFDRS' the set of the required data of the slip being issued.

The SSFDRS receives this data, processes it with a special security algorithm (SHA-1) that creates a hash value (sign) and sends the result of this processing back to the connected computer. The hash value, which represents a sequence of characters and digits is the unique electronic digital "fingerprint" of the data of the slip being issued. Furthermore the SSFDRS saves this hash value into his own working daily memory and issues a relevant slip - receipt with:-

the date,
the time,
the daily ascending sequential number,
And the general ascending sequential number of slip issue.

The supporting software of the SSFDRS which is located in the connected computer receives this "unique summary - signature" ie hash value and prints it along with the other data of the issued slip, while at the same "time signature", in special electronic files. This process is repeated for all issuer's slips.

In the end of the day the SSFDRS processes all the stored hash values of the working daily memory, produces a general daily hash value of all "summaries - signature" of the day, issues a "Z" day report slip, on which the general day hash value is written, saves this hash valued permanently in the secure fiscal memory it includes for that purpose, and sends it to the connected computer.

The computer software receives this unique general .day summary . signature. hash value and saves it in a special electronic file.

Special Secure Fiscal Device for Record Signing (SSFDRS)

A Special Secure Fiscal Device for Record Signing (SSFDRS) is defined as the operationally and naturally Autonomous Fiscal Processing Unit which:-

is connected exclusively with a Special Data Communication Port (SDCP) with the interconnected computer system for the secure signing of the records being issued.
comprises no capability of data import and communication for the signing of the issued slips other than the Special Data Communication Port (SDCP).
is capable of complete disconnection - detachment from the interconnected data communication . receiving electronic system.
holds a self-contained power supply input and consists of:-
a processor executing special software for the processing and marking of the records (tax micro-code),
a special software (fiscal micro-code - firmware) program memory,
a working daily memory,
a real time clock,
a fiscal memory for the permanent storage of financial data
a fiscal printer with a autonomous capability for the issue of the following slips:-
- Daily Fiscal Signing Record Report Slip - "Z" (DFSRRS)
- Daily Summary - Signature Slip - (DSSS)
- Periodical Summary of Memory Reading Slip - (PSMRS).

The SSFDRS is sealed in an inviolable manner, all its operations are justified and controlled by the committee and the supporting software is at the disposal of the Ministry of Economy and Finance.

(Note: The keeping of the stored files of required data of the signing process is regulated by the same conditions as the keeping of the electronic journal, mentioned earlier).

As anyone can easily realize due to the use of the standard algorithm SHA-1 (electronic journal . invoice signing), it is too easy for the authorities to check immediately the stored files of data for any changes.

Important Security Considerations