Questions tagged [digital-signature]

A digital signature (not to be confused with a digital certificate) is an electronic signature that is used to authenticate the identity of a message sender or document signer, and usually to ensure that the original message/document content is unchanged (document integrity).

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What is the solution to digitally sign email apart from S/MIME and GPG/OpenPGP [closed]

I have tried to implement S/MIME, however, I've found out that S/MIME seems to be obsolete, in my perspective. Since S/MIME cannot operate on Google Chrome or Edge. Another solution I found is ...
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436 views

Diffie-Hellman protocol CA, confusing

In the Diffie-Hellman protocol, if the participants have their own private key and a generated public key. How can we determine whether or not they have a trusted CA for authentication or just the ...
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3answers
320 views

Should I sign software release keys with my own key?

A good practice is verifying software with a team signing key, to ensure the software hasn't been tampered with. The problem When I verify a download, I usually stumble upon the following message: $...
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1answer
76 views

Sign a lot of messages with same private key [closed]

I'm creating platform where I need to sign a lot of messages (1k/sec), I want to use Ed25519 signature, because it has the best performance. Is it safe to sign that many messages with the same private ...
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1answer
106 views

How useful is PDF signing in real world usage?

Background senario: So we had a problem where our system (Alice's shiny widgets) generated a PDF with a quote amount for 10 widgets. Someone (Eve) took the PDF, altered it to increase the price by 20%,...
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Are there any reasons to add a payload signature to a REST API with mutual TLS?

We have a B2B REST API with Client Certificate authentication. Are there any reasons to add also a payload signature check to this API? I'm seeing many service providers which add a digital signature ...
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2answers
842 views

File carving JPG exif data files

So I'm very new to info sec overall but I would say I am least experienced in Digital forensics, anyway I recently had the opportunity to work with professionals and we did manual file carving. This ...
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1answer
414 views

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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1answer
437 views

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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Which (FOSS) tools (on Linux) support displaying or verifying digital signatures [closed]

So far I have been unable to find any tools on Linux (preferably FOSS) which will display a digital signature when viewing a PDF file and possibly also allow verification of the validity of that ...
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323 views

Comparison of signature algorithms HMACSHA1 and RSASHA1

Compare and contrast the signature algorithms HMACSHA1 and RSASHA1. Assume that the aim here is to make it infeasible to generate valid message+sig pairs without knowing a certain private token/key (...
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Can't understand how stuxnet was bogusly signed

Wikipedia says that Its device drivers have been digitally signed with the private keys of two certificates that were stolen from separate well-known companies, JMicron and Realtek, both ...
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Is it safe to store APK signing passwords in private git repository?

I develop android game using cocos2d-x. For android release, it contain this fields in proj.android/gradle.properties: # uncomment it and fill in sign information for release mode #RELEASE_STORE_FILE=...
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3k views

Amazon AWS KMS - Concept of signing in general and with JWT

Looking into Amazon AWS KMS (Key Management System). Got confused since the methods exposed via Amazon AWS API are only to encrypt and decrypt (https://docs.aws.amazon.com/kms/latest/APIReference/...
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1answer
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Is Ed25519 still secure, despite the fault attack published in 2017?

I heard that Ed25519 is a new digital signature. It has smaller public key size and generates a public key more quickly. I read an article about Ed25519 titled Practical fault attack against the ...
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1answer
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Can I describe the PDF's certificate-based signatures using W3C's DSIG Core?

Can I map the specialized specifications of PDF's certificate-based signatures into the [XML DSIG Core] standard? I'm imagining PDF as an "XML file analog", to be mapped into the W3C's ecosystem. ......
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35 views

How to assign not-PDF file by digital certificate?

XML, EPUB, etc. formats need also to be signed by digital certificate, like in the PDF's certificate-based signatures. There are reliable open-standards and open-source software to accomplish it? PS: ...
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1answer
860 views

How can you change the plaintext of the given secret message which is in AES-256 CBC

Say you have the secret message encrypted with AES-256 in CBC mode 5a04ec902686fb05a6b7a338b6e07760 14c4e6965fc2ed2cd358754494aceffa where the first 16 Byte is the initial vector, the second 16 Byte ...
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1answer
82 views

How to cryptographically guarantee that data came from a trusted application on a mobile device?

I'd like to have an open source application generate data and sign it in such a way that anyone with access to the data alone can know for sure it was generated by that open source code. More ...
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1answer
119 views

How can I limit which key sizes and signature algorithm of the next certificate in the certificate chain are allowed?

I have walked through the different fields of x509 certificates and came across some fields which enable to limit the usage of the certificate (for example for certain domains). Is it possible to ...
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1answer
155 views

DNSSEC - does the domain owner owns a key?

The purpose of DNSSEC is to prevent some attacks like cache poisoning so a client can be sure that the answer it gets from a recursive DNS server are correct (the IP is the correct IP). The root DNS ...
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1answer
466 views

How do I detect if the public key in a digital certificate is modified?

I know how the basic process of digital certificate, but how do I detect if the public key in a digital certificate is modified?
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745 views

Self-signed CA and digital signatures

I am asked to design the public key crypto system for an IoT-like devices. These devices are going to be talking to each other over TCP/IP as well as communicating with a cloud-based API server. The ...
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Signing with multiple end entity certificates

Let's assume we are having a structure with a root certificate with lots of "child" certificates. A message is transmitted which is signed by any of the child certificates. The receiver has stored ...
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537 views

computing the exchange hash for ecdsa-sha2-nistp256

I am writing code for an SSH server and can not get past the Elliptic Curve Diffie-Hellman Key Exchange Reply part of the connection. The client also closes the connection and says "Host Key does not ...
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532 views

Token FIPS 140-2 level 3 with support for Android, iPhone and Web

I'm testing a SafeNet 5100 token FIPS 140-2 level 3. It comes with programs to access and manage it, but only for desktop machines. I would like to create applications that use level 3 tokens. Is ...
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How does digital signatures provide integrity? [duplicate]

Digital signature provides authentication by encrypting the text with the sender's private key and decrypting the text with the sender's public key. But how do we add integrity to it so that the text ...
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2answers
1k views

Does asymmetric encryption guarantee data integrity?

I have some unusual size constraints for my data which may be relevant to the prescribed solution. The scenario is as follows. Secure server A generates 240 bytes of data that need to be consumed by ...
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1answer
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Checking Certificate Signature

Here's my problem: I'm trying to enable HTTPS on a local site for learning reasons. The thing is, I don't want to generate the certificate with some well-known application, but i want to create a ...
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1answer
164 views

Server pagination with key in response to fetch next page

I want to introduce pagination in one of my server endpoints. The endpoint will have an option to include in the parameter the last index of the previous page, and if included, the "page" returned ...
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1answer
1k views

Is it safe to use jku, kid and x5u in JSON Web Signature (JWS) header?

I don't get what header parameters like jku, kid, x5u are for in JSON Web Signature (JWS). Since We have to verify the integrity of the content against secret key/public key, is it safe to leave jku, ...
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1answer
249 views

Does a signed hash reveal any information about the original message?

As part of the end to end encryption for my app, I am following the standard procedure of using RSA to exchange the temporary AES256 key. Currently when A decides the key to send to B, he encrypts it ...
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1answer
91 views

Is it wise to remove redundant self-signatures from my PGP key?

I have changed expiration date of my pgp key several times. Recently I looked at it and started to worry about the mess I can see there: $ gpg --list-sigs AAAAAAAAAAAAAAAA pub 4096R/AAAAAAAA 2014-...
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3answers
788 views

Why does Github need to offer a GPG signature feature?

Github offers users to sign their work using GPG. I guess I missing the bigger picture, though how can people have your SSH keys or your credentials and not your GPG keys. Not sure what kind of layer ...
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1answer
649 views

Is “BEGIN PGP SIGNED MESSAGE” optional to include in an armored message?

Although it's probably nitpicking, it doesn't look very cosmetically pleasing to put the BEGIN PGP SIGNED MESSAGE at the top of an email, is that header really required to parse the message and verify ...
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1answer
368 views

How many times does a DNS server need to sign?

I have a question about DNSSEC and how many times a DNS server must sign or in other words, how many signatures are there in a day. I know that DNSSEC builds on a chain of trust starting at the root ...
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760 views

Is it safe to use a Windows executable with expired SHA256 certificate but valid SHA1 certificate?

Microsoft's Media Creation Tool to create Windows 10 installation media has a SHA1 digital signature and a SHA256 digital signature (shown via file properties). However, the certificate for SHA256 ...
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2answers
94 views

How do we change the public key in our commercial app?

We have a commercial library that uses a public key to sign an XML request that goes up to our license server. The response that comes back is XML that has been signed with our private key, and the ...
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GPG RSA Authenticity Mechanism Minimum Requirement

The GPG/PGP based RSA authenticity signing mechanism is based on 3 parts to ensure authenticity: the public key the signature the fingerprint of the public key Assuming that the author keeps his ...
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2answers
141 views

Multiple digital signatures [closed]

I have the following case scenario: One document that needs to be signed digitally (using an external signing service) by 4 different people. The 4 people must be present while signing the document ...
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1answer
175 views

Does the ECDSA signature value (of an OCSP response) need to be DER encoded

In OCSP responses by a certain eIDAS PKI I every once in a while get signature values which, when unpacked from their BIT STRING, contain an ECDSA signature whose INTEGER constituents have an ...
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446 views

Use of S/MIME capabilities attribute

If you examine an S/MIME-signed file with $ openssl cms -in file.sgn -noout -cmsout -print you see that S/MIME capabilities are also included in the signature: ... object: S/MIME Capabilities (1.2....
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1answer
907 views

How do you get the PE file hash of a signed file?

I have a PE binary with a digital signature. I want to get the original PE hash (not the hash of the whole file). I can't figure out how to read it from the file. The Authenticode spec suggests the ...
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81 views

Is there any reason to use an encrypted value for the plain text signing key?

I am creating an API and I am thinking of using an encrypted value of some random password as the value to store for the plain text representation of my signing key. Is this just a vain attempt to ...
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1answer
4k views

Where is the public key of the Certificate authority stored? [closed]

I'm talking about SSL/TLS certificate authorities. I know that they store their private key on a very secure location. but what about their public key that our browsers use to make sure the signatures ...
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1answer
615 views

Best archive format for cryptographic signing?

I want to sign a whole directory of files using GPG, and that entails creating an archive or compressed file, since GPG can only sign a file, not a directory. However, I imagine that some archive ...
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5k views

Verify S/MIME signature with no certificate included

Let's sign a file with $ openssl smime -sign -in file -out file.sign -outform DER -inkey private.pem -signer certificate.pem -nocerts With the option -no certs no certificate is included in file....
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1answer
515 views

USBlyzer - Safe Or Not?

I need to use a USB analyzer. I've been looking at a couple of different options. This one came up. As far as I can tell, it's not open source, but seems to be quite popular. Seeing that the data ...
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419 views

Why is it called micalg?

RFC3851 says: The multipart/signed Content type has two required parameters: the protocol parameter and the micalg parameter. and The micalg parameter allows for one-pass processing when ...
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184 views

What exactly is digested in an S/MIME signated-only e-mail?

What exactly is digested in an S/MIME signated-only e-mail? It's definitely not only a sha256-digest of the original message, which means that $ openssl dgst -sha256 <<< "Text" would ...

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