Q: I want to add timestamps when adding digital signatures to PDF documents in PDF Studio. Do you have a list of timestamp servers available?

A: In PDF Studio version 2020, we added support for SHA512 algorithm for communication with timestamp servers.  This FreeTSA – Guide recommends using SHA-512. SHA-512 is part of SHA-2 (read more on md5hashing.net).

Below is the list of timestamp servers that we found working in PDF Studio 2020:


Timestamp Server SHA1, SHA512
PDF Studio 2020+
PDF Studio 2019
http://tsa.safelayer.com:8093/  SHA1
http://ca.signfiles.com/tsa/get.aspx  SHA1
https://freetsa.org/tsr  SHA1
http://tsatest1.digistamp.com/tsa (requires authentication)  SHA1
http://time.certum.pl SHA512
http://timestamp.digicert.com  SHA1
http://zeitstempel.dfn.de SHA1 (Must increase length to 8000)
http://timestamp.apple.com/ts01  SHA1
http://timestamp.entrust.net/TSS/RFC3161sha2TS  SHA1
(no longer in service)
http://tsa.cesnet.cz:3161/tsa  SHA1
https://tsa.cesnet.cz:3162/tsa  SHA1
http://tsa.cesnet.cz:5816/tsa  SHA1
https://tsa.cesnet.cz:5817/tsa  SHA1