Forward-only activation prevents institutional retraction. A degree that belongs to the student forever — employer verification, transcript consent, aggregate research, all from one envelope.
Elena graduates in 2024. Her degree is cryptographically signed at the moment of issuance — forward-only. The signature cannot be undone. The university cannot retract the credential retroactively, regardless of what happens to the institution in the years that follow.
Five years later, an employer requests verification. Elena's device releases a per-employer disclosure projection: degree type, GPA band, graduation year. The employer receives a verified attestation. They do not receive Elena's full transcript, student ID, financial aid history, or disciplinary records.
A second employer making the same verification request receives the same verified attributes but a different disclosure token. The two employers cannot determine they both verified the same candidate.
Degree verification, professional license confirmation, continuing education credits, transcript consent workflows, credential portability across borders — wherever academic records should structurally belong to the graduate rather than the institution.
ABT-E uses Ed25519 digital signatures for authentication of every event at every party. Per-event symmetric keys are derived via HKDF with the event identifier as salt and held in hardware-backed secure storage (Apple iOS Keychain, Android Keystore, or equivalent platform secure-storage). Envelope encryption is performed at the first-party endpoint before any ciphertext leaves the device or origin. Each tier authority’s ciphertext contains only that tier’s authored projection — information not relevant to a tier authority is authored out before encryption, not redacted after. The registry maintains a hash-chained log where each entry’s hash includes the prior entry’s hash, providing tamper-evident integrity across the chain. Forward-only tier activation: registration of a new tier authority causes inclusion of an active tier layer in subsequent envelopes only. Existing envelopes are not retroactively modified. Cryptographic boundary at the first party. Plaintext never moves. Per-tier projection authored at envelope construction. Registry-routed restoration requires structural participation by all three parties.
Cryptography researchers studying envelope encryption, tier-bounded ciphertext, deterministic key derivation, and signed receipt chains in educational credentials and student records.
Privacy researchers studying architectural privacy enforcement, unlinkability, purpose limitation, retention through cessation, and consumer-controlled key custody.
Consumer protection advocates seeking architectural alternatives to policy-based privacy enforcement. Cryptographic structural enforcement, not vendor trust.
Policy researchers examining cryptographic enforcement of storage limitation (GDPR Article 5(1)(e)), data minimization (GDPR Article 5(1)(c)), and consumer protection requirements.
Educational technology researchers studying student privacy (FERPA), credential verification, transcript portability, aggregate institutional outcomes reporting, student-controlled disclosure for college applications and job verification, and cryptographic alternatives to centralized clearinghouse architectures.
