A method for performing a transaction between a legal entity A who has an approval to perform such transaction, and a legal entity B over a network, the transaction being initiated by the legal entity A, wherein the legal entity A, to verify the approval to the legal entity B, associates the transaction with a verification insignia, the verification insignia being a unique transitory insignia provided to the legal entity A by a legal entity C who thereby guarantees that the legal entity A has the approval, the provision of the unique transitory insignia to the legal entity A by the legal entity C being conditioned by the legal entity A providing to the legal entity C a secret identification code confirming the identity of the legal entity A to the legal entity C, the legal entity B validating the unique transitory insignia, and upon positive validation, and only then, accepts the transaction, and the transitory unique insignia being invalidated substantially immediately after the validation.