Buyer authentication: ensuring security in digital sales 

The accelerated advancement of e-commerce has brought enormous opportunities to retail, but it has also magnified the complexity of a challenge that reaches all digital merchants: ensuring that the buyer is actually the cardholder used.   

In an environment where each transaction can become a financial risk, the authentication of the legitimacy of the customer has become one of the strategic pillars for any digital operation. This is because, when a purchase is made with a credit card, there is always the doubt about who is typing the data. If the person is not the real cardholder, he can contest the transaction, with the issuing bank and generate a direct loss to the merchant. Retail, which often operates with narrow margins, can not afford to bear this type of loss.  

Traditionally, stores have turned to anti-fraud solutions, which evaluate multiple signals during checkout.These tools analyze CPF, card data, email, address, behavior history, device usage, and hundreds of variables that, combined, generate a risk score.   

If the system sees inconsistencies, the transaction is refused. However, this process is not perfect. Legitimate customers are also barred, especially when something goes outside the standard, as happens when the bank issues a new card, or when the buyer exchanges mobile phone or address. For e-commerce, the silent loss of revenue caused by false negatives comes with a direct impact on the customer experience: when a legitimate buyer has his purchase refused, the brand also loses credibility.   

This is where authentication technologies begin to gain prominence. The 3D Secure Protocol (3DS), for example, allows the issuing bank itself to validate the buyer. The customer is directed to the bank's app, receives a push or SMS and confirms the transaction. This additional step creates unequivocal proof that it is the holder who is making the purchase, protecting the store from future chargebacks.   

However, even with the evolutions to version 2.0, each bank implements the “defio” in a way, which directly affects the experience. Some flows are faster and more intuitive, taking a few seconds to authenticate the user. Others are still confused and poorly adapted to mobile, which can generate friction and cart abandonment.   

The good news is that version 2.0 allows a silent authentication, without friction with the consumer. In this model, the store sends more data to the bank, which can automatically approve part of the purchases without interruption and request of the challenge, preserving the experience and, at the same time, increasing security.  

The great advantage of this authentication is the call liability shift. When the transaction is authenticated by the bank, the responsibility for a possible chargeback for fraud ceases to be the merchant and becomes the issuing bank. This decreases operational risk and improves financial predictability, two essential elements for growing businesses.  

Another trend that has been consolidating in the market is the use of facial biometrics as a complementary layer of identity validation. Solutions such as IDPay, from Unico, take advantage of the database created during account openings in digital banks and large retailers to create a digital identity network.  

When the customer initiates a purchase, using this feature, the system can confirm whether the face captured by the mobile phone corresponds to the CPF used for the purchase and if this same face is the holder of the card used in the transaction.   

This process happens in seconds and is usually more user-friendly than the 3DS authentication challenge flows of some issuers, especially in banks that do not yet have systems well adapted to the mobile environment. In addition to increasing the accuracy of validation, this approach allows the merchant to approve transactions that traditional anti-fraud would reject. And, in cases of future contestation, biometrics provides powerful evidence that it was the holder himself who completed the purchase.  

For companies that want to scale securely, the most effective way is to combine and orchestrate different tools, anti-fraud, 3DS and biometric validation. At Tuna, we have cases where the implementation of new tools increased approval by more than 20% by reducing undue rejections.  

This integrated ecosystem reduces risk, increases approval rates and protects the customer experience.In a competitive market with tight margins, buyer authenticity is no longer just a security measure: it becomes an essential strategy to drive conversion, ensure operational sustainability and build trust at every step of the digital journey.