The threat of phishing or malicious software (malware)-based attacks is significant and growing, at the same time online banking gets more and more popular. Financial loss may be one of the consequences if credentials get stolen. In many protocols, the transaction information is not secured properly. The proposed Biometric Transaction Authentication Protocol (BTAP) is based on the one hand on the Helper Data Scheme for biometric template protection and on the other hand on a trusted biometric transaction device. BTAP provides data- and person authentic transactions since the relevant information in financial online transactions is fused with a secure biometric template from a verified natural person in a way that it is proven to the executing party, that the transaction, as it is received, was in fact initiated and confirmed by an identified natural person.