A method of configuring a payment terminal to become usable as a payment terminal shared by a plurality of operators with cryptographic segregation between the different operators of the payment terminal, the payment terminal being arranged to communicate with at least one payment provider to perform payment transactions, and being associated with a controlling entity that controls usage of the payment terminal in an operator-selective manner, the payment terminal having a terminal-specific access key stored therein, and a terminal-identification number, the method comprising: transmitting an operator- and terminal-specific transport key, encrypted by the terminal-specific access key, to the payment terminal; decrypting the encrypted operator- and terminal-specific transport key at the payment terminal with the stored terminal-specific access key; wherein usage of the payment terminal by operators and/or payment providers is granted by the controlling entity remotely, without physical contact with the payment terminal, by injecting the operator- and terminal-specific transport key into the payment terminal, i.e. by storing the operator- and terminal-specific transport key in the payment terminal in an unencrypted or encrypted form; deriving, by the payment provider, an operator- and terminal-specific initial-encryption key from an operator-specific base-derivation key using the terminal-identification number, or an additional identification number of the payment terminal, and symmetrically encrypting the operator- and terminal-specific initial-encryption key with the operator- and terminal-specific transport key; transmitting the encrypted operator- and terminal-specific initial-encryption key to the payment terminal; decrypting the encrypted operator- and terminal-specific initial-encryption key at the payment terminal with the decrypted operator- and terminal-specific transport key; deriving (S13, S14), both at the payment provider and the payment terminal, an operator- and transaction-specific encryption key from the operator- and terminal-specific initial-encryption key using a transaction-specific number associated with this transaction, when performing a transaction with the payment terminal; performing the transaction with the payment terminal. transmitting an operator- and terminal-specific transport key, encrypted by the terminal-specific access key, to the payment terminal; decrypting the encrypted operator- and terminal-specific transport key at the payment terminal with the stored terminal-specific access key; wherein usage of the payment terminal by operators and/or payment providers is granted by the controlling entity remotely, without physical contact with the payment terminal, by injecting the operator- and terminal-specific transport key into the payment terminal, i.e. by storing the operator- and terminal-specific transport key in the payment terminal in an unencrypted or encrypted form; deriving, by the payment provider, an operator- and terminal-specific initial-encryption key from an operator-specific base-derivation key using the terminal-identification number, or an additional identification number of the payment terminal, and symmetrically encrypting the operator- and terminal-specific initial-encryption key with the operator- and terminal-specific transport key; transmitting the encrypted operator- and terminal-specific initial-encryption key to the payment terminal; decrypting the encrypted operator- and terminal-specific initial-encryption key at the payment terminal with the decrypted operator- and terminal-specific transport key; deriving (S13, S14), both at the payment provider and the payment terminal, an operator- and transaction-specific encryption key from the operator- and terminal-specific initial-encryption key using a transaction-specific number associated with this transaction, when performing a transaction with the payment terminal; performing the transaction with the payment terminal.