All Will Trust the Integrity of Your Data

International standard PKI Encryption plus Blockchain publication 

PKI timestamp RFC3161

The security demands of a PKI timestamp are unique because both the cryptographic keys and the clock must be securely maintained. DigiStamp utilizes FIPS 140-2 Level 4 tamper-responding certified hardware (HSM), which houses the audited software, clock and all the private non-exportable keys. The HSM's internal clock will not accept adjustments beyond these few, small calibration events per day.

Validation of a DigiStamp e-TimeStamp requires a public key. The validation process itself is immediate.

Internation Standards supported and additional details here: Strong Legal Evidence 

Blockchain Publication

Each PKI e-TimeStamp is recorded sequentially on our systems. Every day, a Merkle tree is generated, beginning with the root hash of the previous tree and incorporating all timestamps created that day. This new root hash is then published and secured through multiple mechanisms, including integration with the Bitcoin public ledger, reinforcing its immutability and reliability.

Details here: Hash-Linking Based Timestamp for renewal