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Questions tagged [timestamping]

Generally, a timestamp is the current time of an event that is recorded by a computer. You can use digital timestamps via a trusted authority to certify and protect your intellectual property or your records integrity.

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What is an “anonymous admissible timestamp”?

Can anybody explain the term "anonymous admissible timestamp" to me? Could you show a case where it is useful to apply it? I came across this term in the comments of a question on the StackExchange ...
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Signed XML SignatureValue element value (hash in base64) contains &#xd

My application is .NET based. I have signed xml from third-party environment (Java based). Its signature value base64 string contains carriage return #xd;. ...
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Why do key exchange protocols need secure clock synchronization?

I'm studying Kerberos and other Key Exchange Protocols. They always (or very often) require that the clocks are synchronized. To this purpose they periodically probe a time-server. This is said to ...
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How truncated timestamps are used?

Consider the following setting: We have a sender $\textbf{A}$ and a receiver $\textbf{B}$. The sender $\textbf{A}$ a wants to send a message $M$ through a channel where each message to $\textbf{B}$ ...
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LTV signatures - Expiry of embedded timestamps

I work for a company which decided last year to offer a PADES (PDF advanced electronique signature) for its clients. We don't do the advanced signature ourselves, we work with external AATL(Adope ...
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Commitment for bid

Alice and Bob are sitting on an online casino table which exposes the following game: the table randomly generates a number R and piblishes this number. The player which "bids" the highest number ...
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Digital signature certificate limited validity period

Digital (or electronic) signature certificate can have limited validity period - 1 year for example. I wonder how this is done technically in asymmetric cryptography. Can someone explain? Say I have ...
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Is there a digital time-stamping scheme that does not rely on a time-stamping authority?

Given a bit string, is it possible to assign it an immutable time stamp that is verifiable as correct without assuming a (one or more) trusted time-stamping authority? A time-stamp is correct if it is ...
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Guaranteed decryption time schedule

Suppose you want to store information in, say, safe container for a certain time, after which you want information to be accessible. Let's assume simple idea and fill details by yourself. Take some ...
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Can timestamping provide evidence of absence before a certain time?

Normally trusted timestamping proves that certain information existed at or before a certain time. However, sometimes there is a need to prove the opposite; that something did not exist before a ...
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Is it possible to have a PAdES signature with only a timestamp?

Is it possible to have a PAdES signature which only contains a timestamp from a TSA? Does this prove the content of the PDF was unaltered since timestamping? Or is the timestamp calculated on a ...
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Is cryptographically signing a time-stamp enough to prove identity when using public key encryption?

For the purposes of trying to secure an API (a cross-site form POST), we need to prove the request originated from a valid party. For various reasons, we cannot sign the entire contents of the ...
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Using a block cipher with timestamp instead of counter

I have a system where machine A sends updates to machine B. The updates are sent over the internet, where each update is a single UDP datagram. Machine A sends a local timestamp in each update (we can ...
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What advantage is there for using a nonce and a timestamp?

I know both nonces and timestamps are used to prevent replay attacks, and nonces may offer increased security in the situation a message could be replayed with the timestamp in the allowable window. ...
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What is the exact meaning of revocationWarning and revocationNotification in RFC 3161?

The RFC 3161 (Internet X.509 Public Key Infrastructure Time-Stamp Protocol) specifies that a time-stamping response has a PKIStatusInfo and, optionally, a timeStampToken. In turn, the PKIStatusInfo ...
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Expire signature

I am looking for a way to have a 'did it expired' key. There's a similar question here, but I have to prevent reusing of the 'did it expired' signature . A possible solution would be a two one-way ...
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Remotely Verify File Timestamp

I'm working for a professor to build a platform for students to take midterms and finals online. The student downloads the test during class (when the professor makes the test available on the server ...
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Detecting Software Changes - Verifying untampered code

This question assumes an environment devoid of any internet connections, the software in questions operates in a non-connected environment on a single machine. I have a piece of software that may be ...
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Replay Attack in Stream Cipher

Stream ciphers are vulnerable to replay attack if the same key k is used. If E() is a stream cipher and an attacker intercepts the message m that's being transmitted at time t, how can the attacker ...
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Requested to encrypt data with AES256, digital certification, timestamped

at my job we have been tasked by gov to encrypt some data we send to them. The "law" says we have to do the title above, but they only need us to do the AES256 thing because the data is not really ...
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How can I know when a file was signed?

I have been thinking about digitally signed documents (Word files and PDF files) and can not get over the fact about - how can I securely know when the file was signed? Scenario: If the date of the ...
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Does OpenTSA support PKCS11 to talk to HSMs?

We are planning to implement the time-stamping service (RFC 3161) using OpenTSA wanted to know: Does OpenTSA support PKCS-11 (Cryptoki) to talk to HSMs? BTW: I did not find documentation or much ...
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Timestamping using a hashed linked list and public known events

Let's say we have a timestamping scheme of the following characteristics, The hashes of the documents we are trying to timestamp are XOR'ed with "events" whose time of occurrence are very publicly ...
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Is timestamping possible without publishing?

The Wikipedia article Trusted Timestamping states that we can timestamp data by publishing it's hash. Publishing can be done either independently or via a third-party publisher, as explained by ...
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How useful is NIST's Randomness Beacon for cryptographic use?

NIST have just launched a new service called the NSANIST Randomness Beacon. It has been met with some initial skepticism. Perhaps the cryptography community would have used it before June 2013 when ...
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A timestamping authority (digital notary)

Does there currently exist a free online service that accepts a file, hashes it, takes an authoritatively chosen timestamp (from one or more time services), signs these and sends this signed message ...
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Why use a timestamp and how can someone know it's the correct one?

Let's say A wants to send a message, so everyone who gets the message, can be assured that it's from A. A then sends a message ...
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Is it possible to cryptographically prove when was the last time a ciphertext was decrypted/encrypted?

I want to provide a service that encrypts and decrypts documents and I want to provide the users with proof that I haven't stolen their secret key and read their documents. I know I can prove when a ...
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Timestamping services authorities, utilizing Linked, hybrid and other than PKI schemes

What are well respected Cryptographic Timestamping authorities utilizing more sophisticated than just PKI (RFC 3161) schemes, like Linked, Linked and signed, distributed hash trees (maybe P2P?), ...
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Signature and Timestamp for Long Term Document Archival Question

I have a PDF document intended for long-term (many years, maybe decades) archival which I would like to digitally sign with my personal certificate to ensure its integrity. As far as I understand, I ...
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How are timestamps verified?

You put an input and the hash value comes as an output then when someone puts the input the hash function it is applied to see if it is the same hash original value is stored in some database , that ...
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Is there an algorithm or hardware that can sign/verify natural time?

PGP/GPG can used to sign text, others use public key to verify them. So one could say, that these cryptographic algorithms deal with space. Are there any algorithms that can deal with time? E.g. I ...