About The NFC Mint
Our Mission
We make StampCats collectibles and tags for your own creations and collections. OnceMark lets makers write a permanent public record. TamperKit lets sellers record seal checks before shipping and on return. Our validation service checks the tags in all three.
What a Tag Check Proves
Each tap makes the chip generate a fresh code. Our validation service checks that code to authenticate the tag. A genuine tag does not by itself prove that the attached item is genuine.
Makers use OnceMark to publish a permanent record. Sellers use TamperKit to keep private records and export cryptographic proof of the evidence chain.
Infrastructure and Security
A hardware security module holds our master key. Each tag's key is derived inside it from the master key and the tag's UID, then passes through our encoding software in memory as we write it into the chip. We do not store tag keys in a database. The system uses:
• Individual Tag Keys
The HSM derives each tag's key from our master key and the tag's UID, so one tag's key cannot generate valid codes for another tag.
• ECC Chip Verification
Every tag is verified against NXP's factory-programmed elliptic curve signatures before enrollment.
• AES-CMAC Attestation
Each scan generates a unique, non-replayable cryptographic proof using the tag's monotonic counter.
• Counter-Based Replay Prevention
Rolling counters ensure old signatures cannot be reused and future signatures cannot be predicted.
• Real-Time Abuse Detection
Automated monitoring for anomalous scan patterns, counter divergence, and clone attempts.
Technology
We use NXP NTAG 424 DNA chips with Secure Dynamic Messaging. A hardware security module holds the master key and derives each tag's unique key from it and the tag's UID. The key cannot be read back from the chip or generate valid codes for another tag.
Every tag registered with The NFC Mint contains a unique cryptographic key. When scanned, the chip generates a signature using its secret key, UID, and monotonic counter. Our validation service verifies this signature and checks the manufacturer's ECC originality signatures of the chip itself.
Validation Methods
URL Validation
Each tap opens a fresh link in your browser containing the chip's ID, updated scan count, and authentication code, which our service checks. You need no app or account; reopening a validated link, including a shared copy, reports a replay.
App-Based Validation
NFC Proof on iOS and Android communicates directly with the chip and verifies NXP's factory signature on your device. This checks the chip's authenticity, which a browser cannot do.
Important Notice
The NFC Mint LLC provides tag authentication and sells its own StampCats collectibles, while items marked with OnceMark or TamperKit tags are made and sold by others. Losses arising from faulty readings or exploitation in the system are at the risk of the end user. Always use multiple means to verify authenticity when making purchasing decisions.
Trademark Notice
NXP and NTAG are registered trademarks of NXP B.V. The NFC Mint LLC has no affiliation with NXP B.V.
Contact
Product Questions
hello@nfcmint.com
Technical Support
support@nfcmint.com