Abstract: The invention relates to a method for producing a cryptographically signed transaction for the transfer of an amount of a currency within a blockchain. The transaction comprises one or more inputs and one or more outputs. The method comprises: retrieving the one or more inputs, the inputs being a reference to one or more previous transactions, determining the one or more outputs, each output defining an amount to be transferred to a receiver indicated in the respective output, adding security information, the security information defining directly or indirectly a maximum amount to be spent with the transaction, and cryptographically signing the transaction by adding signature information.