Tamper resistance

Definition

In practice: after posting you no longer correct, you reverse and post anew. The error stays visible — that is not embarrassing, it is the proof that nobody intervened after the fact.

For electronic archives the question of the medium is added. Where data is stored on alterable media, logs or signatures have to show that nobody swapped anything. A PDF in a folder anyone can overwrite does not meet that.

The wording

Information carriers are deemed alterable where the information stored on them can be changed or deleted without the change or deletion being detectable on the data carrier.

Where to read it

• Ordinance on the Keeping and Preservation of Books of Account (SR 221.431)
• Swiss Code of Obligations (SR 220)

What the software must be able to do

The check is the locking step: does it exist, is only reversal rather than amendment possible afterwards, and does the program log who did what and when? A deletable ledger is grounds for exclusion.

Checked Aug 2026

More terms under Bookkeeping and retention: Accrual principle Accrued liabilities Annual accounts Association accounting Balance sheet Balance sheet total Book value Break-even point Business assets Business expenses Cash book Cash flow statement Cash receipts Contribution margin Cost centre Current assets Debit and credit Depreciation Double-entry bookkeeping Duty to keep accounts EBIT EBITDA Equity Equity ratio Financial year Fixed assets Fixed costs Foreign currency General ledger Gross profit Hidden reserves Income statement Inventory count Journal Journal entry Liabilities Liquidity Loss carry-forward Membership dues Net profit Opening balance sheet Overheads Pass-through item Prepaid expenses Provision Record-keeping ordinance Reserves Retained profit Simple accounts Swiss SME chart of accounts Turnover Value adjustment Variable costs Volunteer-run structure Voucher Year-end closing modules