Performing an online transaction using card information and PIN

A method of performing a financial transaction between a purchaser 12 and a supplier 14 comprises creating an electronic instruction 15 containing encrypted card information (39, Figure 3), including card and bank account details, encrypted security information, including a PIN (40, Figure 3) for the card, and transaction amount information, and operating on the instruction using a secure mechanism 74 providing verification of the purchaser's identity and the instruction integrity. Preferably the instruction is created on a personal computer (50, Figure 3) and the secure mechanism involves a digital signature, a digital certificate, or encrypting the instruction. Preferably in operation the purchaser transmits the created instruction over the internet 16, by email or a WWW browser, to the supplier, who may append payment instructions 17 to the instruction and perform further encryption or security operations 76 on the instruction. The supplier sends, via the internet 18, the instruction to a financial institution having online ATM/POS access 24 to the bank accounts of both the purchaser 28 and supplier 34. The institution decrypts the instruction, verifies the instruction integrity and purchaser's account details, and transfers the required sum from the purchaser's account, accessed via the online ATM/POS link 30, 36 using the purchasers card details and PIN, to the supplier's account. The institution then issues an authorisation message 32 to the supplier indicating the approval status of the transaction. A financial institution having online ATM/POS access to be used with such an instruction is also claimed.