Pain points

Simple authentication methods such as mobile OTP (One-Time Password), mobile authentication apps, mobile phone identity verification, and biometrics are widely used in internet-based financial transactions, which allow for easy authentication with a user's smartphone rather than a separate device. However, it is still difficult to fully block interceptions of personal information incidents in financial services.

- Risk of smishing incidents in mobile OTP

A phishing scam at one bank in Singapore in 2021 demonstrated how mobile OTP remains vulnerable to smishing. As the OTP was delivered by text message via mobile, it was stolen and a fake text message was sent to bank users by scammers. This resulted in at least 469 victims with a loss of around $8.5 million, which lead to the banks' plans to transition to a digital OTP authentication process being put on hold. In Korea, a case in which a hacker installed a remote-control malicious code on a mobile phone through a link in a text message under the guise of a family member, and then used the stolen personal information to obtain a mobile OTP and transfer a large amount of money, has also been noted.

- Related security vulnerabilities compared to physical OTP

Mobile OTP is vulnerable to external cyber-attacks such as hijacking, since it generates OTPs only online, unlike physical OTP devices that generate OTPs even when disconnected from the network. Mobile authentication apps that use a trusted execution environment (TEE) to protect the encryption key for OTP generation are also unlikely to be considered as a perfect alternative because it can be manipulated by malicious code. After all, despite the inconvenience of portability and the need for periodic replacement, physical OTPs still provide unparalleled security in comparison to other two-factor authentication (2FA) methods as mentioned above.

- Smart OTP's limited OS support and operation delay

Smart OTP is evaluated as an incomplete service because it cannot be used on iPhone, despite the advantage of being compatible with other banks, unlike existing mobile OTP. In addition, many problems remain including operational delays in generating OTPs.


SSenStone provides a mobile OTP that can be easily applied to payment cards such as a debit card and/or credit card. Whenever a user taps their mobile device with an OTAC applet embedded debit or credit card, it generates a first OTAC (One-time-authentication code), which is used to generate a second OTAC for their financial transactions. It means that users acquire the advantages of hardware OTP and mobile OTP at the same time; strong security and convenient user experience. Since near field communication (NFC) is possible through the IC chip of the card, it can be applied not only to payment, but also to financial transactions, physical access, system login, and even identity verification.


  • By using a second OTAC for financial transactions generated from a primary OTAC by tapping the card on the back of a mobile device, it fundamentally blocks hackers from stealing the seed value in the memory.

  •  it prevents hackers from infecting someone's smartphone with malicious code and then using that person's information
    through remote control to illegally use financial services such as large sum remittances.
  •  Regardless of Android or iOS, it authenticates payment card registration and financial transactions by simply tapping an OTAC applet embedded card even without entering PIN codes.

Card tapping mOTP_1_eng

Card tapping mobile OTP based on OTAC

SSenStone’s card tapping mobile OTP reduces the hassle of carrying a separate device by adding an OTP generation function to a payment card thus providing strong security through authentication medium separation, normally only provided via physical OTP. A card with OTAC applet embedded generates the first OTAC through communication with the smartphone NFC. Since the first code generated from the card is changed into a second ‘OTAC’ via the application, there is no risk of sniffing, something that can occur during standard NFC transactions.

Card tapping mOTP_2_eng-2

As the card tapping mobile OTP based on OTAC is embedded on a debit/credit card, you can use financial services that require 2FA such as high-value remittance services more safely and easily by simply tapping the payment card on the back of your smartphone. In other words, there is no need to issue a separate physical OTP device for 2FA only. Above all, it provides a safer financial service environment by preventing mobile OTP incidents associated with high-value remittances, including theft of user information from a smartphone infected with malicious code.


Read our 'Toss Bank' case study here

All-in-One Card with integrated mobile OTP

OTAC embedded cards can also be used as a means of diverse authentication beyond payment. Even when logging in to mission-critical sites such as internet banking, you can generate a one-time QR code just by tapping the back of your smartphone. You can also use the same card to enter the office or a restricted area by tapping it on the digital door lock. Businesses can use this innovative card by integrating corporate payment cards, access control devices, and employee ID into one card. High manufacturing costs related to the contactless payment function will be alleviated naturally through additional uses other than payment only.

Card tapping mOTP_3_eng


OTAC, developed by SSenStone, is the original technology that provides all of the following features at the same time.

Main Large

    OTAC is a dynamic code, which means the code keeps changing. As a result, you don’t need to worry about any leak of your personal information, such as your card details, because the codes must have already been changed when others try to use them.

    The network connection is NOT necessary at all for generating OTAC.

    Reducing an authentication stage that requires the network connection directly means there are fewer gateways for the hackers to access our personal information.

    Moreover, this feature enables users to authenticate even when they are in networkless environments, such as on the plane, underground, rural or foreign areas.

    swIDch can guarantee that the code never duplicates with anyone at any given moment.

    There is NO chance of someone else having the same code.

    The users or their devices can be identified with the code alone.

    Once OTAC has been generated, providing OTAC alone is already fully sufficient to identify the user as the code is unique.

    It means, you can forget about the bundles of static information including IDs and passwords.

University of surrey

The University of Surrey, one of the leading global cyber security companies in the UK, conducted OTAC algorithm analysis and academic verification of SSenStone. For the full text of the thesis, please visit the University of Surrey website and download the report.

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5F, 329, Cheonho-daero Dongdaemun-gu, Seoul, Republic of Korea

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Korea Office (SSenStone)

5F, 329, Cheonho-daero Dongdaemun-gu, Seoul, Republic of Korea (02622)

Tel : 02-569-9668  |  Fax : 02-6455-9668

UK Office (swIDch)

swIDch Ltd Office 176, 1st Floor, 3 More London Riverside, London SE1 2RE

Tel : 020-3283-4081