TSA. Decentralized timestamping on the blockchain With the advent of cryptocurrencies like bitcoin, it has become possible to get some level of secure timestamp accuracy in a decentralized and tamper-proof manner. Digital data can be hashed and the hash can be incorporated into a transaction stored in the blockchain, which serves as evidence of the time at which that data existed. For proof of work blockchains, the security derives from the tremendous amount of computational effort performed after the hash was submitted to the blockchain. Tampering with the timestamp would require more computational resources than the rest of the network combined, and cannot be done unnoticed in an actively defended blockchain. However, the design and implementation of Bitcoin in particular makes its timestamps vulnerable to some degree of manipulation, allowing timestamps up to two hours in the future, and accepting new blocks with timestamps earlier than the previous block. The decentralized timestamping approach using the blockchain has also found applications in other areas, such as in dashboard cameras, to secure the integrity of video files at the time of their recording, or to prove priority for creative content and ideas shared on social media platforms. See also Timestamp Timestamping (computing) Cryptography Computer security Digital signature Digital Postmarks Smart contract CAdES – CMS Advanced Electronic Signature PAdES – PDF Advanced Electronic Signature XAdES – XML Advanced Electronic Signature References External links Internet X.509 Public Key Infrastructure Time-Stamp Protocol (TSP) Policy Requirements for Time-Stamping Authorities (TSAs) Decentralized Trusted Timestamping (DTT) using the Crypto Currency Bitcoin ANSI ASC X9.95 Standard for Trusted Time Stamps ETSI TS 101 861 V1.4.1 Electronic Signatures and Infrastructures (ESI); Time stamping profile ETSI TS 102 023 V1.2.2 Electronic Signatures and Infrastructures (ESI); Policy requirements for time-stamping authorities Analysis of a Secure Time Stamp Device (2001) SANS Institute Implementation of TSP Protocol CMSC 681 Project Report, Youyong Zou Time Authentication methods