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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9
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3answers
4k views

Can a zero knowledge proof of voting be made using a trusted auth server (without client side crypto)?

Questions: Can one implement a secure voting system having all the features described below? e.g. without disclosing any individual's vote to the government server (or the third party), preserving ...
19
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7answers
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Is there a protocol that provides data integrity, but not encryption for HTTP?

HTTP I'm aware that HTTP sends plain text over the network which can be sniffed and modified if a MITM is performed. HTTPS On the other hand, HTTPS sends encrypted text over the network that can ...
11
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2answers
690 views

What real life scenarios require separate end user certificates for Signing and Identity?

Based on this question, I'm interested in any rational argument that would support the idea of maintaining separate signing and authentication certificates. Conventional logic & wisdom says there ...
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2answers
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Does my PGP key really need to match the e-mail address for which I'll be using it?

In considering whether or not I want to join the big web o' trust and put my keys on a key server, I got to thinking about how it would affect my e-mail address' exposure. I generally try to keep my ...
8
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2answers
932 views

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 ...
13
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3answers
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Can signing too much compromise a private key?

Can a collection of many messages signed with the same private key be abused to either forge signatures so some (but not all possible) messages, or even worse to reconstruct that private key with less ...
10
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2answers
533 views

Electronic identity and digital signatures - why they are different?

It seems (to me at least) that is is generally accepted that "electronic identity" and "digital signatures" are a different thing. For example, in the Estonian ID card there are two certificates - one ...
10
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3answers
26k views

What is the difference between an electronic signature and a digital signature

From Wikipedia: An electronic signature, or e-signature, is any electronic means that indicates either that a person adopts the contents of an electronic message, or more broadly that the ...
6
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1answer
476 views

self-signatures using SHA1

This page says: self-signatures must not use SHA1 You can check this by doing: gpg --export-options export-minimal --export <keyid> | gpg --list-packets |grep -A 2 signature|grep '...
6
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2answers
5k views

Dealing with expired or revoked signing certificates with Infopath documents

Suppose I have an Infopath form that is digitally signed today by a valid, and active user. When that user leaves the company, we disable the account and revoke the certificate. This causes a problem ...
6
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2answers
3k views

What are the real-time applications of long term digital signature with timestamp

I want to know the real time applications that uses digital signatures with timestamps. Specially I am interested to know the applications where we can trust an old signed document which is now ...
4
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1answer
945 views

How to acquire DNSSEC root trust anchor from IANA?

I want to establish trust in a DNSSEC record. I found, that it can be done $ dig +sigchase +trusted-key=./root.key @8.8.8.8 eesti.ee root.key could be obtained with $ dig . DNSKEY @8.8.8.8 | grep -...
4
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2answers
873 views

Using digital certificates in digital signatures

Please could anybody explain to me how certificates are used with digital signatures? I understand difference between certificates and signatures. It is clear. Digital certificates are used to ...
2
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1answer
264 views

In the context of advanced electronic signatures, what does “sole control” mean?

To satisfy the conditions for an advanced or qualified electronic signature, the power to sign must remain under the "sole control" of the signatory. Can anyone provide concrete examples of what this ...
8
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2answers
3k views

How do systems protect against a stolen code-signing certificate after the certificate expires?

Imagine this scenario: 1st December 2014 - a certificate is stolen and used to sign malware with 2014-12-01 timestamp. 15th December 2014 - the certificate is revoked. Malware will be prevented from ...
4
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1answer
9k views

Details of TLS certificate verification

I do understand the cryptography basics, but I am uncertain about the following three steps: Step 1: How to compute a TLS certificate Correct me if I am wrong: The certificate authority computes a ...
4
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1answer
2k views

How to verify a server key exchange packet

I have a problem between two ends of an SSL connection. The server sends ServerKeyExchange and the client says the server key exchange packet is not signed correctly, so I want to check the signature ...
3
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2answers
3k views

Signed request vs HTTP digest auth for API authentication?

By signed request I mean something like this (simplified example): Client creates a sig in his request: $sig = hash('sha256', $api_key.$data); which generates 7409ur0k0asidjko2j for example. He then ...
3
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2answers
6k 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....
2
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1answer
666 views

What happens if my signing subkeys are compromised?

Let's say my subkeys are compromised, but my master keypair is safe and secure, so I revoke the old subkeys and issue new ones. With encryption keys, the results are pretty clear: I can still decrypt ...
1
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1answer
147 views

Keeping signatures valid even after the private key has been compromised

If I understand the topic of digital signatures correctly, you sign a message via hashing+encrypting it using your private key. Then, if a private key is compromised by an attacker, she could sign ...
13
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1answer
567 views

What are the problems with encrypted but unsigned data?

In another question's answer, D.W. wrote: Make sure there is authenticity protection for the encrypted data (e.g., encrypt and then sign/MAC): you will need both confidentiality and authenticity ...
9
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1answer
2k views

How do certificates work in terms of encryption, hashing, and signing?

I think I might understand this stuff, but I want to be sure I've got the details correct. There is a lot of information out there on the high-level implementation of certificates, as well as the ...
8
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3answers
4k views

Why are apps signed?

From the Android website: Android requires that all apps be digitally signed with a certificate before they can be installed. The signature ensures that only the original developer can publish ...
8
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2answers
214 views

Verifying cryptographically signed files when the key has been revoked

This is mostly a question out of idle curiousity. If I use my private key to sign a file today, forming a signature, and distribute that signature with the document to someone they can then use my ...
7
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1answer
1k views

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 ...
6
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1answer
4k views

Signing session cookies

The Play Framework for Scala has support for signed session cookies. In the application configuration file is an "application secret" that is set as a secure random number when the application source ...
5
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2answers
575 views

A method for securely sharing centrally-stored documents among a changing set of users?

I believe it's possible to meet these requirements only if a third party is involved in a manual process. For example: Each user is given the same public key The private key resides offline at a ...
5
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1answer
289 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 ...
3
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3answers
4k views

How does the digital signature process work?

I'm trying to understand the process of digital signature verification, however I don't quite get the explanation in my book. If A wants to send a message to B with a digital signature, the process ...
3
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1answer
947 views

API request signing best practices

I am reading how different services are handling API signature and authentication. Particularly I was looking at: AWS Signing v4 WeChat Signature Algorithm Alipay Digital Signature Google Maps API I ...
3
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1answer
2k views

Regarding Openssl.config file: What is the importance of policy matching when creating a self-signed certificate with the aid of this file?

When trying to go through some material for self-signing a certificate, one of the steps required me to set policy conditions in this config file. See: https://www.phildev.net/ssl/opensslconf.html ...
3
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2answers
101 views

Signature that can only be verified by author and recipient - without pre-shared key

Desiderata: Alice wants to send a message to Bob for him to keep and to be able to refer to, such that Bob can be certain that the message came from Alice and was not tampered with. Alice also wishes ...
3
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1answer
3k views

What is the difference between a digital signature and whole message encryption?

I am newbie in information security I am trying to understand the difference between a digital signature and encryption of a message. Lets consider simple example of email message. I understand how ...
2
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2answers
2k views

Why is a CSR hashed?

What are the use cases for defining something other than the default SHA1 hash in a CSR? Is it to protect the digital signature, public/private keys? What is it protecting exactly?
2
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2answers
3k views

PKCS#1-1.5 encoding - is there a reason to use 00 in block type?

For encryption block looking like this: EB = 00 || BT || PS || 00 || Data where BT - block type and PS - padding string, I've read that we use three types of BT - 00, 01, 02. Now, since 00 and 01 are ...
1
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3answers
2k views

In message signing, is the digest encrypted with a generated symmetric key or with the sender's private key?

I understand the encryption process uses a generated symmetric key to encrypt a message, and then encrypts the symmetric key with the receiver's public key before it is sent across the wire. This ...
1
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1answer
29 views

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. ......
1
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1answer
964 views

is pkcs#7 suitable for signing and encrypting zip files?

I'm looking to protect zip files that I will be regularly sending to a 3rd party. I need to ensure strong confidentiality and non-repudation. I would like signing/encryption to be based on ...
1
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1answer
556 views

How can I verify if a person is in my web of trust?

Lets say I trust person A (whose public key is in a key server) and I want to know if I can also trust person B (pub key is also in a key server). How can I verify that I have a chain of trust ...
0
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4answers
247 views

Is it possible to digitally sign information with a password?

I'm creating a cloud storage service and need to have the ability to provide reliable security for clients. In my previous question, I used a different schematic and said I would post a new question. ...
15
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6answers
3k views

Why not RSA-encrypt the entire document?

I have recently learned of a way for person B to verify that a document sent from person A is indeed from person A. Person A gives Person B his public RSA key. This must be done reliably. Person A ...
9
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4answers
1k views

What good, standard digital signature / timestamp verification clients are widely or easily deployed?

I'm looking for a good way to publish data along with a digital signature (and ideally a timestamp) which is as easy as possible to verify via software run locally on public data. For example, ...
9
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4answers
1k views

What's the point of providing file checksums for verifying downloads? [duplicate]

Many projects offering binaries, also offer hashes (e.g. SHA256) of those binaries, wither as .ASC files, or directly on the web page near the binary. This isn't to protect against network-caused ...
7
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4answers
9k views

when people say a file has a checked md5 hash, what exactly does that mean?

ok I was just reading this site: http://www.zdnet.com/blog/bott/stay-safe-online-5-secrets-every-pc-and-mac-owner-should-know/3542?pg=4&tag=mantle_skin;content and thought of something I always ...
6
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1answer
10k views

How to check executable code signing signatures?

How can I see all code signing signatures an executable has? I know that requests for a tool are usually considered as opinion based, but I really can't find one and I don't expect many answers. ...
5
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2answers
161 views

How do I prepare for Certificate Authority end of business?

We are deploying a security solution which uses certificates to validate documents. These certificates are issued by our government-authorized CA. What if in a distant future, the CA who provided us ...
4
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3answers
355 views

What if somebody sends me genuine certificate that they do not own? [closed]

I just started learning about the digital certificates, its architecture and how it works internally. What will happen if someone sends me a genuine certificate for authentication which does not ...
4
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1answer
73 views

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 ...
4
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2answers
1k views

Distributed XAdES-X and XAdES-A signatures over multiple documents

As the standard is not completely clear in this matter, I'm trying to found out if the XAdES standard (ETSI TS 101 903 v1.4.2) describes distributed case in which the SigAndRefsTimeStamp element or ...