An advanced electronic signature (AdES) assures both senders and recipients of two goals. First, that the document has not been subsequently altered (integrity); and second, verification that those whom the document identifies actually signed the document digitally (authenticity).
A check guarantees that the signature has not been altered, and it shall be deemed invalid if it’s been tampered with.
You can also increase the security of the AdES with an SMS-TAN procedure where you ensure that your document actually reaches the person you want. The AdES is sufficient and legally valid for the majority of signed documents in Germany. Among other things, these include offers and orders, brokerage agreements, delivery bills and insurance contracts.