flexSecure Java Card Implant

The flexSecure is a developer friendly in vivo platform for digital identity, cryptography, and blockchain applications secured in a subdermal NFC implant.

  • Implantable 8mm x 28mm secure element contactless smart card
  • JCOP 4 OS for Java Card 3.0.5 applets on 167736 bytes of available EEPROM
  • Common Criteria EAL 6+ and other national certification schemes
  • Factory default master key, ready for developers to immediately deploy apps
  • 5mm (4G) Flex Install Needle Included! *Details & Warning


More Information

The flexSecure is a subdermal contactless secure element enabling fully autonomous separation of your cryptographic keys and functions from vulnerable general computing platforms such as your smartphone or computer. The ability to not only carry your OTP, PGP, and other cryptographic keys with you at all times, but also perform cryptographic functions in vivo (generate OTP codes, encrypt & decrypt data, etc.) without ever revealing private keys to the NFC interface you are interacting with is a huge step forward for personal digital identity and data security.

flexSecure Kit Contents

Your flexSecure kit comes with the following items.

    • Pre-sterilized flexSecure implant in tyvek sterilization pouch
    • Custom 4G (5mm) flex installation needle (unlubricated)
    • 1 packet of sterile surgical needle lubricant


  • 1 packet of topical anesthetic Numbing Gel
  • –>

    Use of your flexSecure

    The flexSecure uses a SmartMX3 P71 chip from NXP. It comes with factory default master key set, and with ISD: A000000151000000 (OP_READY) and the card manager applet PKG: A0000001515350 (LOADED) so it’s ready for use with GlobalPlatformPro. Full documentation is available via public repository located at https://github.com/DangerousThings/flexsecure-applets/tree/master/docs.

    flexSecure Applets

    You are free to compile and load any applets you want of course, but we are maintaining a repository of open source applets and associated tools for your convenience at https://github.com/DangerousThings/flexsecure-applets/. If you would rather have an easy to use app-store like experience to deploy and manage your in vivo secure applications, check out Apex Flex.


    • The P71 chip in the flexSecure only allows a handful of incorrect master key attempts before permanently and irreversibly bricking itself. Changing the master key from factory default is necessary for security, but losing the key has no recovery process. Bricking the P71 has no recovery process. Proceed with caution.
    • The flexSecure is for advanced users. Compiling applets, deploying applets to the flexSecure, and using your flexSecure with various applications all require some amount of mastery over the various domains involved. We do not offer direct support in any of these areas, however the community forum will have a place for flexSecure discussion.

    Professional installation notes

    The flexSecure is approximately 8mm wide by 28mm long, with an average thickness of 0.4mm. Installation should always be done by a professional.

    • Do not install under any gripping surface (e.g. no palm side installations)
    • Do not install atop or parallel to any joints (flex devices are only “semi-flexible”)
    Scalpel Procedure
    • Make a 8mm wide incision in skin
    • Lift & separate dermal layer using elevator tool
    • The subdermal “pocket” should be at least 35mm deep
    • Remove all tools from installation site
    • Slide flex device under skin with sterile gloves – no forceps or tools
    • Suture to close wound – do not pierce flex device while suturing
    Needle Procedure
    • Incise skin using a 4g (5mm diameter) piercing needle, bevel side down
    • Carefully insert the needle to a depth of at least 35mm (video)
    • Be sure to lift the skin ahead of the needle’s point as you insert it
    • Slide flex device under skin with sterile gloves – no forceps or tools
    • Achieve complete hemostasis before applying bandaging
    • Use re-enforced butterfly bandage or dermal strips to pull wound closed
    • Apply transparent film (tegaderm) dressing overtop the dermal strips
    • While hemostasis is maintained, do not remove bandaging for 7-10 days

    Important things to know about the flexSecure

    – The biopolymer is ISO 10993 and USP Class IV tested and certified, however the final product has not been tested post-processing, meaning material changes during processing could render the final product unsafe in some way.

    – There is no “preferred” location for installation of a flex device. Customers are free to install a flex into any area of the body their installation professional is comfortable with, as long as it is in the fascia layer between dermis and muscle tissue and not in an area of flexion or under a gripping surface. Even though we use images which suggest installation above the second metacarpal of one of the fingers, it is not an ideal location for such a device. Fingers are filled with tendons, nerve bundles, and very important things all packed into a very tight space. We urge you to think about easier locations like the back of the hand or in the arm/wrist.