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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Send a CA certificate via email without a digital signature?

If a friend wants to send me his S/MIME CA certificate containing his public key, why does he need to add a digital signature? A digital signature verifies that the content was sent by him and not a ...
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36 views

Who should create the keys?

I'm trying to implement a Software deployment & updating function which is part of AUTOSAR AP standard. Background information: There are three parts. Integrator the client which user uses it ...
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62 views

How can I apply message digest to the application so that user can validate the accuracy and completeness of the software

I have developed the application and now it's time to distribute to my users. I was reviewing my application and reading security best practises and found below statement in one of the article. ...
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How to solve this digital signature problem

I was wondering if it's possible to achieve the following with any cryptographic technique: A set of persons generates a public/private key pair and everyone registers their public key in a public ...
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72 views

How to communicate Credit Card details to customers when instantly approved in PCI-DSS compliant way?

Would displaying the full Credit Card details (PAN, Expiry date and CVV/CVC) in Online Banking and / Mobile Banking be considered both PCI-DSS and secure? Or what would be Best practice to display the ...
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What is the advantage of using a digital signature over simple asymmetric encryption?

If you're sending me a message, you can: a) Encrypt the message using your private key, and I can decrypt is using your public key. b) You can create a digital signature of your message, and then ...
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85 views

How to verify an email signature from Facebook?

Facebook allows users to add OpenPGP public keys to their profile; these keys can be used to "end-to-end" encrypt notification emails sent from Facebook to your preferred email accounts. – ...
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Can attackers change the public key of certificate during the SSL handshake

The communication is not encrypted during the SSL handshake. If an attacker conducts a man in the middle attack between server and client to capture the certificate, and change the public key in the ...
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63 views

What use does verifying a file with a signature downloaded from the same server have? [duplicate]

Now, I understand how PGP signatures work and why they can be useful to check if a file has been manipulated but this has always bugged me, if I download a file from a site/server, and read: "...
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Offline code signature verification scheme

Assume that I want to sign digitally updates for an offline appliance (lets say a limited linux VM). To begin with, such mechanism is not in place and the very limited OS doesn't have any CA ...
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126 views

Is a cryptographically signing camera possible?

What kind of digital / cryptographic signing would make it possible to create a camera that cryptographically signs the photos it takes so that the images can be verified to have been taken with that ...
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Can you sign using a digital certificate itself?

Googling I saw several lectures saying that it is possible to sign using digital certificates. I am confused about that, because according to my knowledge it is possible to sign only using the private ...
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Some digitally signed pdfs shown as verified in the pdf viewers while others are not [closed]

I have two pdf documents: 1 - My class 10 marksheet issued by the CISCE that I downloaded through digilocker. 2 - My Domicile certificate issued and downloaded from the aaplesarkar website. Both ...
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113 views

Can a document be digitally signed multiple times, successively by different users?

The question is, if a document that is collaboratively edited, one user per time, could be digitally signed by every editor before it is passed to the next editor. And if yes, could the final receiver ...
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Signature of a root certificate - CA authority

Created a root certificate(cacert.pem) and tried viewing the content to primarily understand the contents of certificate, mainly the signature appended to certificate. Below is the text output of ...
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Can I sign with two Code Signing certs to build reputation on the newer one?

I recently acquired a Microsoft Authenticode Code-signing certificate as a new certificate using an identical name to another one which will expire soon. Obviously, the new certificate has no ...
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Is it possible to use WebAuthn for digitally signing documents in the browser?

WebAuthn is a relatively new API for authentication, and it uses public key cryptography instead of something like passwords. I am wondering if it is possible to use the cryptographic part for a ...
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139 views

How do digital signatures work - beginner's explanation?

I'm new to cryptography, and I'm confused about digital signatures. How do they work? Please illustrate with an example in a way that a beginner can understand.
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What happens if the private key of a Trusted Timestamp Authority is compromised?

what happens if the private key certificate of a Trusted Timestamp Authority used to sign the timestamps is compromised? If this private key certificate is changed, should all timestamps be re-signed ...
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Windows Smart Screen pops up after EV Code Signing

I am code signing my application's installer using an EV Code Signing that we have bought recently at work. The code signing is performed when the installer is created using Inno Setup (version 5.6.1)....
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How to keep track of file authenticity while offline

I have an application running the client/server model and offering an online and an offline mode. Each user can read, create or modify text files (even in offline mode) that will be present on his ...
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Why isn't the record of a TLS data application exchange signed by the server?

I am inspecting the TLS(1.2) protocol, and I notice that after the key exchange (handshake), data applications flows from server to client freely (because they have the session key). However, I ...
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Protect transaction counter agains roll-back attack

I am designing a application which should be used for transaction processing so required very good performance. There are requirements that transactions originating from the same client must have ...
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74 views

What prevents the client from changing the signature in files?

From what I can tell, some software licenses work client side. For example, when looking in to the purchased software for the first time, the server will return a software license. In order to ...
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How do AV vendors select malware signatures?

AVs use signatures to identify malware which are often strings of bytes or regular expressions thought to be unique to that malware. Do reverse engineers select these signatures by hand or do they use ...
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What is the difference between PKCS#7 and CADES, PADES and XADES?

I am newbie in PKI. For signing a pdf documents we are free to consider each pkcs#7 format or PADES format. If I have some misunderstandings, please turn it on for me.
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How to protect file integrity and history containing counters

I would like to create a solution that would sign the data and will have a increasing counter so I can track the number of signatures. One of the requirement is to have an increasing order of ...
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36 views

Cracking signing and HOTP blackboxes

If there are these blackboxes, both are using algorithms which are considered secure yet: Blackbox will sign any message, no limit for messages to be signed. Blackbox will generate 8‐digit HOTP code ...
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Server to Server Communication RSA or x509 Certificate

I want to build Server (My) to Server (Other Client parties) web service and I want to add security layer for client verification. Do I need to force clients to create x509 Certificates or RSA key ...
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What's the point of a digital certificate for which no private key exists?

I am only using digital certificates to sign documents, and my understanding is that the correct flow is the following: create a private key (e.g. using openssl) create CSR using the previously ...
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1answer
140 views

Why is validating the integrity of the plaintext necessary in addition to validating the integrity of the cipher text?

Reading the iOS Security Guide's description of the iMessage encryption protocol I'm trying to figure out why they included a mechanism for verifying the integrity of the plaintext as well as ...
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81 views

Is there a file system allowing read-only access enforced by cryptography

Is there a file system standard (like LUKS) that allows anyone who can plug in the hard drive to read files, but requires a passphrase to modify or write? For example, I can do something similar by ...
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154 views

How do I create a detached plain text signature?

If I use gpg --detach-sig file, then I get a small file.sig, but it is not plain text, so this is not useful if you wish to send the signature in a plain text format. If I use gpg --clearsign file, ...
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How to understand: digital key encryption, public key decryption in Digital Signature? [duplicate]

How to understand: the sender in the digital signature encrypts the message digest private key and sends it to the receiver. The receiver then decrypts the public key. We say that asymmetric ...
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213 views

How secure is using MD5 for signature

Generally speaking, MD5 is considered as broken for secure usage these days, but I came across a signature design using MD5 many times recently in my company. The detail shows as following: T = text, ...
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87 views

Using same algorithm for signing and encrypting a message

If we use the same algorithm to encrypt and sign a message, what can happen if the message is intercepted and read by a third party?
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65 views

What does “probabilistic algorithm with random tape” mean?

I am new to the study of cryptography, and when reading papers they often mention that "probabilistic algorithm G with random tape w ...". What does it mean by "random tape w"? I mean why it does is ...
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46 views

Asymmetric Encryption + Signature workflow

Let´s say that Alice wants to send an encrypted message that only Bob can read, plus confirm that Alice is the person that wrote that message. What is the procedure that will take place? When I see ...
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Is it possible to build an ASiC container out of a file and its timestamp token? [duplicate]

If I have: A file, X The RFC3161 timestamp token of X Are these sufficient to build a (single file) ASiC container with the file and the timestamp? In other words, is the timestamp included in the ...
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64 views

Signing and encrypting with pairs of keys based on discrete algorithms

In case I've generated pair of keys (public and private) for RSA, I'm able to use it both for signing and encrypting. Is the same statement true also for pairs of keys based on discrete algorithms?
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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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Is it possible to save a verifiable log of a TLS session? [duplicate]

Here's an example situation: I download a file from some server over https, but I also save a "log" of the TLS communication. Later, that file is removed from the server and nobody believes me when I ...
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129 views

Is GPG a kind of digital signature?

So I've been using GPG since I've touched Linux&LibreOffice, but I only knew that's its a signature, for identifying the work is created by me. But soon I've been touching some law questions and ...
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28 views

Proving that a certain site had given page at certain time [duplicate]

Lets someone opens https://foo.com and saves the page using "save page as". Is there any way to prove later that the locally saved files have not been altered assuming that we trust the server public ...
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1answer
401 views

SHA1 signature in a SAML request

I'm currently looking at the security of a KeyCloak implementation, which again uses SAML 2.0 identity provider. I'm not too familiar with SAML, but during the authentication, the sent SAMLRequest ...
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How to sign a text in a way, so it can not be altered or split in parts unacknowledged

Given, I want to create a document (text-only for the sake of this question) and give it to someone I do not trust. I am not allowed to publish it myself. It's probably not going to be published (...
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60 views

Why is digital signature enforcement on webservers not common practice?

Why is it that server admins do not code sign the contents of their webservers (all php, css, js, etc.) and have Apache / NGINX / whatever server software refuse to execute or serve any code / ...
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121 views

Signing JWTs with server's SSL/TLS certificate

I have a server that needs to sign JWTs asymmetrically. I can either generate a new public/private keypair or re-use my keypair used for my server certificate. Is there any concern about re-using my ...
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Signing webhooks with asymmetric keys

I want to sign webhooks from my web service with a JSON Web Signature (part of JWT standard), ideally using asymmetric keys (so, using RSA or elliptic curve cryptography). What is the recommended or ...
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70 views

What are the risks in returning digitally signed payloads over an insecure HTTP connection?

Let's say I own a service and a client needs me (for the sake of this question) to provide an endpoint over HTTP (not HTTPS) that doesn't use cryptographically secure authentication. Further, there's ...