Soulbound Tokens (SBTs)
Understanding the core technology behind PsicoStacks credentials.
What are Soulbound Tokens?
Soulbound Tokens (SBTs) are non-transferable NFTs that are permanently bound to a wallet address. Unlike regular NFTs that can be bought, sold, or transferred, SBTs represent credentials, achievements, or identities that should remain attached to their owner.
In PsicoStacks, your psychometric credentials are minted as SBTs, ensuring they cannot be sold, transferred, or forged. They are cryptographically tied to your wallet, proving authentic ownership.
Key Properties
Non-Transferable
Once minted, the SBT cannot be transferred to another wallet. This prevents credential theft or fraudulent selling.
Verifiable
Anyone can verify the authenticity of an SBT by checking the blockchain, but only authorized parties can view the full data.
Revocable
The credential owner can revoke their SBT at any time, immediately invalidating all verification attempts.
Time-Bound
SBTs can have an expiration date, after which they are automatically considered invalid.
Smart Contract Implementation
PsicoStacks SBTs are implemented using Clarity smart contracts on the Stacks blockchain:
(define-public (mint-credential
(recipient principal)
(schema (string-ascii 32))
(commit (buff 32))
(ttl-blocks uint))
(response uint uint))
;; Creates a new SBT with:
;; - recipient: wallet address
;; - schema: credential version
;; - commit: SHA-256 hash of encrypted data
;; - ttl-blocks: validity period (~52560 blocks = 1 year)The contract stores only metadata on-chain. Sensitive psychometric data remains encrypted off-chain.
Why SBTs for Credentials?
✅ Prevents Fraud
Cannot be sold or transferred, ensuring credentials represent the actual owner's abilities.
✅ Portable
Share with unlimited employers without retaking tests or asking providers for verification.
✅ Privacy-Preserving
Only a commitment hash is on-chain. Full data is encrypted and accessed via time-limited tokens.
✅ Bitcoin-Secured
Stacks anchors to Bitcoin, inheriting the most secure blockchain's security guarantees.
On-Chain vs Off-Chain Data
Stored On-Chain (Public)
- Credential ID
- Owner wallet address
- Schema version
- Commitment hash (SHA-256)
- Expiry block height
- Revocation status
Stored Off-Chain (Encrypted)
- Full psychometric report
- Raw test scores
- Percentiles and insights
- AI-generated analysis
- Personal identifiable information