Stamper provides an rfc3161 Timestamping Authority accessible over HTTPS at:-
https://timestamp.stamper.itconsult.co.uk/stamp-tsa
which supports the hashes: sha256, sha384 & sha512
The first step is to create a timestamp query (TSQ), which generates a hash of the document (for example "examplefile.txt") to be timestamped:-
$ openssl ts -query -data examplefile.txt -no_nonce -sha512 -out examplefile.tsq Using configuration from /usr/lib/ssl/openssl.cnf
The generated TSQ is then submitted to Stamper, which provides a timestamp response (TSR):-
$ curl -H "Content-Type: application/timestamp-query" --data-binary '@examplefile.tsq' -o examplefile.tsr https://timestamp.stamper.itconsult.co.uk/stamp-tsa
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 1265 0 1177 100 88 1027 76 0:00:01 0:00:01 --:--:-- 1104
The contents of the TSR can be shown by:-
$ openssl ts -reply -in examplefile.tsr -text
Using configuration from /usr/lib/ssl/openssl.cnf
Status info:
Status: Granted.
Status description: unspecified
Failure info: unspecified
TST info:
Version: 1
Policy OID: tsa_policy1
Hash Algorithm: sha512
Message data:
0000 - a0 29 a9 9b 34 41 55 65-dc 67 15 2a c3 7b 1e a0 .)..4AUe.g.*.{..
0010 - 03 1c 65 68 aa e9 fd d2-46 b6 03 d1 e5 c3 fe ea ..eh....F.......
0020 - f3 b3 6c b2 e1 bc b8 78-66 b7 81 1f 64 8d b8 b8 ..l....xf...d...
0030 - ca 68 22 3d 68 ee 5b 75-7a 01 3e 73 d9 c7 cf 5f .h"=h.[uz.>s..._
Serial number: 0x20436B
Time stamp: Dec 20 17:57:32 2025 GMT
Accuracy: 0x05 seconds, unspecified millis, unspecified micros
Ordering: yes
Nonce: unspecified
TSA: DirName:/C=JE/O=I T Consultancy Limited/CN=Stamper Timestamping Key 1
Extensions:
Inconveniently, rfc3161 uses hexadecimal numbers whereas Stamper uses decimal. Thus, the serial number 0x20436B equates to Stamper-Id 2114411. What Stamper also does, is to timestamp the TSR with PGP and it is the PGP timestamps which are chained together.
The corresponding PGP timestamp can be retrieved and examined:-
$ curl -o examplefile02.asc https://timestamp.stamper.itconsult.co.uk/get-sig-pgp?stamperid=2114411
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 257 0 257 0 0 5047 0 --:--:-- --:--:-- --:--:-- 5140
$ cat examplefile02.asc
-----BEGIN PGP SIGNATURE-----
Comment: Stamper id: 2114411
iHUEABYKAB0WIQT/IHN7o3gaHZ+7jLHo6IPRD28swgUCaUbjjAAKCRDo6IPRD28s
wuVlAQCSex1Ln8zOX+YO1XU/7KBYdgiGn9JzK7huALTRCv++uQEA1I5fTEYSsOAu
l3Jvm2Q4slC2+97WqeoKCCSrYDv+PwY=
=NRja
-----END PGP SIGNATURE-----
The authenticity or the TSR can then be validated:-
$ gpg --verify examplefile02.asc examplefile.tsr gpg: Signature made Sat 20 Dec 2025 17:57:32 UTC gpg: using EDDSA key FF20737BA3781A1D9FBB8CB1E8E883D10F6F2CC2 gpg: Good signature from "stamper.itconsult.co.uk - Timestamping Key" [full]
Finally, the TSR can be validated against the original data:-
$ openssl ts -verify -data examplefile.txt -in examplefile.tsr -CAfile stamper-ca.pem -untrusted stamper-tsa.pem Using configuration from /usr/lib/ssl/openssl.cnf Warning: certificate from 'stamper-tsa.pem' with subject '/C=JE/O=I T Consultancy Limited/CN=Stamper Timestamping Key 1' is not a CA cert Verification: OK