Questions tagged [timestamp]

For questions relating to physical or digital timestamps, usually as part of a cryptographic protocol, logging, or auditing requirement. Please use the tag [time] for questions relating to system clocks.

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Using Openssl for Package signing with timestamp

We started with openssl dgst to sign and verify packages successfully. Then we thought we should do a timestamped signatures. That's when the process is bit unclear. We used the openssl ts commands to ...
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3 answers
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Proving that a file existed at a time

How do I acquire the means to prove in the future that I had possission of a file now, without relying on the integrity of a single entity? (I believe one way of doing it would be to put the file ...
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How hard to hack are S3 Last-Modified timestamps?

Context: There are many reasons for wanting a very trustworthy timestamp on a document, as discussed in many other questions here such as this one I wrote in 2010. E.g., in an election auditing ...
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eIDAS qualified timestamp on email

Every document that needs to be eIDAS compliant needs to have a qualified timestamp. If we take an email as a document, then the email, based on eIDAS regulations, needs to have an qualified timestamp ...
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What's the PROPER way to validate a signature timestamp?

the purpose of adding trusted timestamps to signatures is so that they can be considered valid long beyond the validity of the signing certificate. However, this is not so easy, since TSA's signing ...
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2 votes
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What are the main constraints x9.95 imposes on RFC3161

So x9.95 seems to be a trusted timestamping scheme built on top of RFC3161. I couldn‘t find a good definition though how it differes or what additional constraints it imposes. Can someone list the (...
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Looking for an RFC5816 token that does not use default hashing algorithm

I'd like to test some code that should be compatible with both RFC5816 (https://www.ietf.org/rfc/rfc5816.txt) as well as RFC3161 tokens. The problem is that all timestamping services that I found so ...
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Why does RFC5816 not change the version number defined in RFC3161

So, RFC5816 https://www.ietf.org/rfc/rfc5816.txt changes the specification of RFC3161 https://www.ietf.org/rfc/rfc3161.txt RFC3161 specifies the 'version' field in TSTInfo to be set to 1 Why does ...
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OpenSSL cli: how to extract ESSCertID or ESSCertIDv2 from SignerInfo of timestamp token

If I have a Timestamp token, then the signing certificate for the token is identified via the ESSCertID (for RFC3161 tokens) or the ESSCertIDv2 (for FC5816) of the signing certificate, which is the ...
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What header & footer to use when storing RFC3161 token in PEM format

The RFC3161 (https://www.ietf.org/rfc/rfc3161.txt) specification states 3. Transports There is no mandatory transport mechanism for TSA messages in this document. The mechanisms described ...
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How to store RFC3161 token for long term validation?

My question is about how to properly store RFC3161 tokens, so that their validity can be verified for a long time (aka "long term validation") Let's say I use an RFC3161 (https://www.ietf....
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What's the merit of storing LTV (long term validation) information for RFC3161 tokens and what happens if a TSA private key would leak?

I'll formulate my question in regards to timestamped PDF, but I wonder actually about the long term validation of RFC3161 tokens in general. So, PAdES has the concept of Long Term Validation, which ...
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In the time side channel, is there any way to improve the measurement time accuracy?

I want to measure the execution time of a function. The execution time of this function is only slightly different in the two cases. Is there any way I can accurately measure its time to distinguish ...
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Best practice for encrypting data on Mifare

I am currently playing around with Mifare Classic 1k. And everything I have read about it's security is true. So it's not exactly the best thing to use to avoid cloning. But I was wondering if someone ...
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2 votes
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Should I re-timestamp old timestamps when switching to a stronger algorithm?

One of our clients uses a trusted timestamp service to prove that certain documents existed on the day they were created (they don't need a full digital signature, just the timestamp). The server uses ...
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3 votes
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Openssl cms verify signature with timestamp and crl

I've used OpenSSL cms to sign the data and generate a detached signature. As per my requirements, I need to timestamp the signature as well, so that if the certificate expired, verification of ...
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Is it safe to assume that my computer's clock will always be synced with actual time within the second or a few seconds at the worst?

Years ago, I was running a service where the moderators were able to do various actions with massive privacy implications if the accounts or contributions were less than a short period of time. I did ...
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Why generate dedicated issuer CA for TSU certificates?

I've observed the practice of generating dedicated issuer CAs for signing TSU (Time-Stamping Unit) certificates instead of just using another existing issuer CA, for example, one used to sign S/MIME ...
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Is it possible to get the original UUID1 from a timestamp?

Say, for example, I generate a time based UUID with the following program. import uuid uuid = uuid.uuid1() print uuid print uuid.time I get the following: 47702997-155d-11ea-92d3-6030d48747ec ...
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3 votes
3 answers
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Is it possible to track someone by sharing a youtube link with timestamp?

Is it possible to track someone by sharing a youtube link with them with a timestamp such as &t=1s if they click on it on their end? I've recently have been told not to use timestamps because of ...
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2 answers
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TSA server with OpenSSL

From OpenSSL documentation of openssl-ts command: HTTP server support is provided in the form of a separate apache module Does anybody know which module is the one? I haven't found any module to ...
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3 votes
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Verify PKCS#7 (CMS) detached signature with timestamp with OpenSSL

I have a PKCS#7 (i.e., CMS) detached signature of a file that is signed by my signing certificate and then timestamp signed by a TSA that is all generated by an application we wrote. I would like to ...
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1 vote
1 answer
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Is it possible to verify that a signature was made prior to the content of the document it is found on?

In What to do after I signed a blank sheet of paper given to me by my manager?, a distressed individual (B) has signed a blank piece of paper and given it to an adversary (A). A has openly stated to ...
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Signing and timestamping implementation

I am writing a software that records and stores data files. I want to digitally sign and time stamp these files so that I can assure that it's Contemporaneous and Attributable (to comply with 21 CFR ...
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How to have both TLS and Time Stamp Signing for data?

As you know, we use TLS for multiple purposes, including integrity, confidentiality and authentication and we use TSAs (Trusted Timestamp Authorities) to have signed timestamps for our data. (Read ...
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1 vote
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Is it possible that a usb drive manufactured 3 months ago can have data copied to it that shows the file last modified date before manufacturing date? [closed]

I have some data that needs to be handed to a friend. I don't want to give the original drive (drive-1), so I plan to purchase a drive (drive-copy) and copy data to it. The data copied will still show ...
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If a file on USB drive shows a certain "date modified" time in the windows explorer, can the correct added date/time be checked for the file?

If someone copied files from a drive-1 to usb-drive-2, then it seems the directories and files get the original modified time from drive-1 in some cases and in some cases not. Can it be checked if ...
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How can one make sure that some specific directories are fully deleted (without any record of their deletion) from a USB/flash drive?

It seems data resides in USB somewhere until it's completely overwritten. But is there a way to delete big directories 10-100GB or so without zero-filling the remaining space and only eradicating ...
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1 vote
2 answers
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Is it possible to verifiably timestamp a video?

I am wondering if there is a way to timestamp a video. (e.g. Security camera footage) I know that there is a way to timestamp a document with a trusted time authority, and it will certainly be ...
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2 votes
3 answers
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How to capture not only the mtime but also the ctime when making forensic copies of files?

Context I'm investigating a compromised Linux box where I found files with malicious code. The file system is too big to just make a copy of the whole block device and so far I'm only interested in ...
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1 vote
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Error while Verifying OpenSSL Timestamp Response

Good morning. I'm having a weird issue while verifying a response from a TSA (TimeStamping Authority). I'm using the TimeStamping Service from the ERMIS Gateway (Hellenic Public Administration). I use ...
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3 votes
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When would a Authenticode signature expire?

I'm curious about how Windows check the Authenticode signature. For example, I would sign test.exe I know that if test.exe doesn't have a TS (timestamp) signature from a TSA (Timestamp Authority)...
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1 vote
1 answer
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Do any third party time stamping signature services exist?

I'm wondering if there exists any trusted third-party service that I can submit a file, or just a signature of a file, and get back a signature of that file signed with the timestamp of when it was ...
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1 vote
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Use of ESSCertIDv2 in a RFC 3161 Timestamp

A qualified trust service provider under eIDAS uses ESSCertIDv2 for their time stamp tokens, but ESSCertIDv2 was not present in the RFC 3161 specification, it was added later in RFC 5816. RFC 3161 in ...
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12 votes
1 answer
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What is the purpose of JSON Web Token (JWS)'s issued at "iat" field?

RFC 7519 specifies an optional "iat" field, indicating when a token was issued. The RFC provides a terse commentary: This claim can be used to determine the age of the JWT. What is the ...
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4 votes
2 answers
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Does x509 have an "issued at" timestamp? Can you tell when an x509 certificate was issued?

The JWT Spec (RFC 7519) has an issued at field ("iat"). Does x509 have any analogous value? I see a Validity field, but nothing else time related.
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How to timestamp a document without electronic signature under eIDAS

I need to timestamp a file to prove data integrity, not authorship. I will use a RFC3161 qualified timestamping service. From the EU Regulation Section 6, Article 41, I understand that I can use a ...
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2 votes
4 answers
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How to extract TSA certificate from tst file?

I have several timestamp token files that I think should have TSA certificates embedded within them because the "Request TSA certificate" option was selected when I requested them with TimeStampClient....
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1 vote
1 answer
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Adding custom embedded Precertificate SCTs into the certificate?

It it possible to insert a list of ct certificate timestamps in the my own certificate created in by internal CA using openssl configuration file. I didnt find any information about ASN.1 sequence ...
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Dual Code Signing: Should SHA-1 signature have a SHA-1 or SHA-2 timestamp?

I am signing executables for our software both with a SHA-1 and a SHA-256 signature. In addition I timestamp both of these signatures. Here I am wondering: I can timestamp the SHA-1 signature with a ...
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5 votes
1 answer
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Any Known countermeasures against clock skew fingerprinting?

I know lots of websites that do clock skew fingerprinting using tcp timestamps. I know how to disable timestamps but i want to know techniques that can be used to counter clock skew fingerprinting. I ...
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4 votes
1 answer
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Issuing TSA (Time Stamping Authority) certificates

What is a practice for issuing TSA (Time Stamping Authority) certificates? I read that TSA certificates should be issued directly from Root CA, but basically TSA certificate is end entity certificate ...
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6 votes
1 answer
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Mitigate Time Spoofing Attack

Say Alice receives synchronized time from Tina the timekeeper. Say Ted spoofs a GPS signal, fooling Tina about the current time. Tina sends this fake time to Alice. What can Alice do to avoid being ...
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3 votes
2 answers
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Can a time stamp protect a signature with the obsolete SHA1?

I am trying to figure out the scope of SHA1 deprecation for existent signatures. Reading this.An attacker (after 110 years) could present a fake document for a valid signature I believe this only ...
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Why AdES -A signatures require TWO timestamps?

Latest ETSI standard CAdES, XAdES and PAdES require for baseline profile LTA to fulfill previous LT, T and B levels. Summarizing,the conformance requirements are: B : Base signature with content-...
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38 votes
9 answers
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How to prove a picture was taken before a certain date? [duplicate]

I need to prove that all my pictures were taken before a certain date. Is uploading them to Picassa, Flickr or a similar service a good way to achieve such timestamping?
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39 votes
2 answers
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How to prove that a file was not created in advance

Sometimes we need to prove that a file was not created in advance - a good example is warrant canaries. The person releasing them may have been forced to sign the file with a future timestamp. For ...
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5 votes
1 answer
286 views

How to put the "trust" into trusted-timestamping

As a part of my thesis, I am about to evaluate different approaches to establish the trust in trusted-timestamping performed by a TSA (see RFC3161 - Trusted Timestamp Protocol). A trustworthy ...
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3 votes
1 answer
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Is RFC 3161 necessary?

As I've been implementing RFC 3161 software components, I got to thinking about running my own TSA and how one really proves the integrity of a time stamp (preferably without violating patents). I ...
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1 answer
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How to prove that something happened before some time in a distributed way? [closed]

To prove that something happened after some time in a distributed way, just refer to something publicly know just before. Is that right? (Though I wonder how to make the time granularity smaller.) ...
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