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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MS-Word and Digital Signatures

We would like to digitally sign DOC (MS-Word) and PDF documents using PKI. Is this possible using an internally deployed CA? I've found lots of articles getting email digitally signed but almost no ...
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Is this explanation about how SSL Certificate Signatures work correct?

I was reviewing some information about SSL certificates and came across an explanation I believe to be incorrect. The explanation is of how signatures and hashing algorithms work in the context of ...
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152 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 ...
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463 views

Adding a “comment” to PGP mail signature files?

I have started signing my mail with PGP, and it attaches the file signature.asc to my messages to verify that I sent them with content, as you'd expect, like this: -----BEGIN PGP SIGNATURE----- ...
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370 views

Is a mail secure if it's PGP-encrypted, but unsigned when sent with DKIM?

I run my own mail server and would like to use different addresses on the same domain. If I were to sign mails from those addresses, I'd have to generate new PGP keys for each and every one of them. ...
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68 views

What problem does PKI fix; how would someone “lie about their identity”? [duplicate]

What does having a certificate issued by a Content Authority protect against? In everything I've red (and watched) they teach it as "you are given the public key to communicate with Alice, but how do ...
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2answers
106 views

Digital signature: How do I know what I'm signing?

Suppose I have to sign a PDF form. If I'm using (say) Acrobat Reader and a hardware security token, at some point I will be prompted for a PIN to authorize the token to sign the document. How can ...
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199 views

What is the difference between the “sig” files and the checksum files, such as on the PuTTY download page?

This is about the functional differences between sig files and checksum files and how they can be used by a user downloading some software. For example, on the PuTTY download page both sig files and ...
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1answer
123 views

Where does the list of trusted content authorities come from when using a web browser?

I was asked "how do browsers know whether or not to trust the certificate from the server it's connecting to" and thought it was a pretty good question. After doing some googling I found two answers: ...
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685 views

Is piping a `ssh-agent` signed message as a password secure?

There's an encrypted filesystem on a server I ssh into using public key authentication. Since a forwarded ssh-agent can deterministically sign a message (see also the ssh-agent protocol section 2.6.2),...
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1answer
69 views

Need asymmetric encryption(not signing) where server encrypts and client decrypts

So I'm trying to build a licensing server, where the licenses of the applications need to be checked when logging in or when the application gets used. But some of those application work offline most ...
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1answer
66 views

How do key pairs work especially in the context of cryptographic signatures?

Is it the case that any message encrypted with a private key can be decrypted with its matching public key and any message encrypted with a public key can be decrypted with the matching private key ...
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819 views

What agency digitally signed Cryptowall 2.0 so that it can run without being detected?

What agency issued a digital signature for the Cryptowall 2.0 ransomware virus? Is it too early to tell? As far as I know this is how Microsoft planned to prevent malware, by adding a digital ...
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2answers
116 views

Specific clarification on how https server public key is trusted

I know the general concept of how digital certificates works: e.g. server "signs" the message it wants to send to the client using his private key and sends along a message digest and on the receiving ...
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1answer
163 views

Encryption and Signature with same RSA private key

Talking about cipher-suites that use RSA both for sign of DH parameters and for digital signature. The keys used for these process are the same, or is there a public and private key for each one? If ...
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1answer
156 views

Certificate - Digital fingerprint vs Signature [duplicate]

What is the purpose of the « fingerprint » section of a x509 certificate, and is there an issue using SHA1 for it ? I understand the certificate signature section, but I can’t see the point with the ...
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2answers
189 views

Where is my missunderstanding in how digital signatures are used with licence files to allow program to run?

I'm trying to learn how digitally signing a licence file helps prevent piracy. For example say an application only runs if it verifies the date as specified in a licence file has not past. Obviously ...
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1answer
47 views

How can I guarantee non-modification of data with signatures?

I am required to design a system where auditors can come along some time in the future, examine historic data, and be sure that the data has not changed since it was stored. I have a spec that ...
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1answer
845 views

How does signing work with Elliptic Curve Crypto?

So I have read up and have a decent understanding of how the crypto works with Elliptic Curve Cryptography. I also think I have an understanding of how signing works with things like Elliptic Curve ...
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2answers
764 views

With javascript in the browser, how can I sign some data without directly manipulating a private key?

With JavaScript in the browser, I need to digitally sign some data. I'm looking at the new Crypto.Subtle api, specifically the sign() and importKey() methods. I want, very reasonably I feel, to ...
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1answer
37 views

How to verify signature while downloading log4j?

From the log4j download page. The PGP signatures can be verified using PGP or GPG. First download the KEYS as well as the asc signature file for the relevant distribution. Make sure you get these ...
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1answer
96 views

RSA signature on TLS

In a TLS handshake using ECDHE-RSA, the ServerKeyExchange frame must include the ECDHE ServerPublicKey, signed with its RSA private key, as specified in the RFC 4492. Got it. Trying to implement an ...
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211 views

How to encrypt with ECDSA?

Suppose there's a transaction in the blockchain in which a given address transfers bitcoins to whoever. I need to encrypt a message so only the owner of that address will read it. I have his public ...
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258 views

Assuring Client is Authorized to use JSON Web Token

JSON Web Tokens ( JWT ) are server-signed objects that the issuing server uses to identify a user, track session data and authorize requests. The fact that JWT are server-signed gives assurance that ...
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338 views

Run our own Certificate Authority for internal use only: safe or not? [duplicate]

According to the guide at How to Run Your Own Certificate Authority, my organization have a plan to issue our own digital certificates for internal use only (the managers will sign PDF documents to ...
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207 views

What the most trustworthy way to demonstrate digital File Integrity?

I'm looking for ensure the integrity of uploaded files and demonstrate this integrity to a user. In my current scenario, a user sends multiple files in several different formats, these files are ...
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1answer
119 views

Is algorithm used to sign defined by certificate?

Using pfx certificate to sign or cypher, the algorithm used (rsa-1_5, rsa-oaep-mgf1p, etc) is defined inside pfx certificate? Certificate has information about algorithms used? Or it's totally ...
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237 views

Significance of the difference between DSA and RSA in signature verifying speed

I have run openssl speed and the output on my CPU for longest available DSA key size, which is 2048 bits: sign verify sign/s verify/s rsa 2048 bits 0.029185s 0....
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281 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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339 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 ...
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498 views

Simulation of cloud based digital signature with Hardware Security Module (HSM)

I am working on a cloud-based digital signature with a Hardware Security Module (HSM). I know that PKCS#11 AND Microsoft CryptoAPI implementation is required. I want to simulate the total process. For ...
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167 views

What encryption and signature systems (don't?) allow for plausible deniability of the OP's key being used?

I need to prevent Mallory from blindly matching encryption and signing keys to messages Hypothetical scenario: A user creates a public key An encrypted or signed payload exists. With only public ...
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Does any nation-state CA (certificate authority) have a public API to verify digital signatures? [closed]

There are around 200+ nation-states on the planet. Most of these use eIDs. Do any of these nation-states have a public API to verify digital signatures? Example: Nation-state Canada issues a eID to ...
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Nation-state digital signatures - how is my public key linked to an identity? [duplicate]

A bitcoiner trying to understand the nation-states. When I use my eID (I'm swedish and I have 'BankID'), and I sign something with my private key that's in the 'eID-file' that I've got on my laptop, ...
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3answers
2k views

Help verifying downloaded Kali image

I am following instructions as shown here Operating Windows 7, so have downloaded GPG4WIN. Next instruction: is to enter this command: $ wget -q -O - https://www.kali.org/archive-key.asc | gpg --...
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1answer
35 views

Is there a cryptosystem that allows a set of auditors to confirm that they have valid Shamir or Group signatures?

Suppose I have a client that generates and sends a Shamir key (or group signature) to a set of Auditors. This key is essentially an unverified set of bytes. Each auditor wants to somehow verify that ...
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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 ...
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2answers
79 views

Understanding digitial certifications

q1) Does that mean that every time information is exchanged, both the original data + digital certification is sent? Meaning data + signature for each and every exchange. q2) Can any kind soul here ...
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1answer
789 views

How do I verify a GPG signature attached for a cleartext email using the gpg command line?

I received an email in cleartext from someone with a signature.asc attached. Looking at the raw source for the email, it was sent with Apple Mail + GPGMail. Reading the message in Thunderbird + ...
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237 views

Why can I sign but not encrypt?

-edit- After following a chain of links from this question I see this is similar/duplicate of Why should one not use the same asymmetric key for encryption as they do for signing? but this question ...
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Combinations of key exchange and signature algorithm in TLS

Let's say that one does not trust ECC a lot, and values confidentiality over authenticity (perhaps simply for the reason that MitM is more difficult than passive eavesdropping and decryption later on)....
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Untraceable Digital Cash?

I have read some articles regarding digital cash that is untraceable (Here). Their protocol is provided below Withdrawal: Alice creates an electronic coin and blinds it. Alice sends the ...
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4answers
2k views

A “good enough” digital signature, with short key

In my application, I want to hide debug feature behind a password. I don't want the password to be easily known by issuing strings executable, so I want to rely on digital signature. We want Debbie ...
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1k views

Confidentiality in Digital Signature

Recently I have been working on Digital Signature. Some common reasons for applying a Digital signature to communications are Authentication, Integrity and Non-repudiation. Does Digital Signature also ...
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1answer
55 views

Is there a way to sign a 624 bits message on 256 bits

I'm looking for a way to sign a 624 bits message on 256bits (sig length = 256 bits) with an asymmetric keys system? I'm trying to sign a qrcode so a client can be sure that this qrcode has been ...
4
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1answer
312 views

Difference between public key and private key validity period

In the section about certificate extensions, the ITU-T X.509 recommendation writes: The private key corresponding to a certified public key is typically used over a different period from the ...
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1answer
3k views

Parsing a PKCS7 detached signature hash

I'm trying to manually verify signatures of Apple iOS Passbook files, which are PKCS #7 detached signatures of the RSA key of the Apple developer who created the file. Which means there's a file "...
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openssl verify signature

For S/MIME, I now know I can verify PKCS#7 detached signatures with: openssl smime -verify -in detachedsign.pem -content content.txt But what about non-MIME messages? So if I sign the message Hello,...
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1answer
385 views

Is it a safe to hardcode my secret key in my iOS app?

Cloudinary iOS SDK configuration suggests to hardcode your api_secret in your iOS app's source code. Isn't that a security vulnerability since string literals can be extracted from the app binary, e....
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Can an embedded CRL be trusted?

Embedding CRLs in a signed document will allow the signature to be validated "long term", by providing a snapshot of the signer's state the moment the document was signed. Im wondering if these ...