Tagged Questions

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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Can Fiddler decrypt HTTPS traffic when using elliptic curves + client cert authetication?

Case 1 involves TLS + client certificate authentication with both client and server using secp384 based EC certificates. In this case, when monitoring traffic via fiddler, the tunneling/handshaking as ...
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26 views

How can I read data from a smart card to authenticate a user? [migrated]

I have a requirement where the user will use a smart card (Token) connected to his PC. When he accesses the web site I need to authenticate the user by reading certificate information from the smart ...
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1answer
51 views

Would it be possible to verify ownership of digital currency without a network connection to an authority server?

Lets imagine the Fed start registering digital USD for use in offline e-wallets, and they figure out a way to make it so that only registered wallets can make transactions. Without an online ...
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1answer
57 views

Why are PGP signatures not more widely used as an authentication method?

Example: Bob generates a key pair for this example. Bob registers at example dot com where he provides his public key. When Bob will try to log in, example dot com will ask him to sign a random ...
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2answers
93 views

Code Signing Confusion

I usually make free windows applications, now I want to digitally sign them. So users can be sure that its from me. But instead of buying the code signing certificate, I thought I may create my own. ...
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1answer
10 views

What are valid OpenPGP revocation signature types?

I'm working on an analysis of the full OpenPGP keyring (ca. 3.8 million keys). I imported all keys to a local instance of hockeypuck (keyserver implemented in go). Hockeypuck uses a PostgreSQL ...
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1answer
60 views

Understanding Digital Signature

I have just learned Digital Signature and am trying to ensure that I have got my understanding of Digital Signature on the correct track. Assume Alice wants to send a message (M) to Bob where the ...
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480 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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73 views

is Digital Signature vulnerable on the Internet?

We all know about how Digital Signing works. I just have some questions about vulnerability risk. At first, As I know, the Signature and the Data are separated and we can split the document into two ...
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164 views

How safe are signed git tags? Only as safe as SHA-1 or somehow safer?

How safe are signed git tags? Especially because git uses SHA-1. There is contradictory information around. So if one verifies a git tag (git tag -v tagname), then checksouts the tag, and checks that ...
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1answer
66 views

What does verified file in windows mean? And does it guarantee related files?

Often when I run a .exe file in Windows, a small box pops up that shows that file is from a verified publisher (e.g Microsoft) or in other case, unknown publisher. I know public key encryption can ...
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3answers
44 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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1answer
40 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 ...
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1answer
120 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 ...
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1answer
52 views

Is there any asymmetric scheme provides signature with length of 30 bytes?

I want to send short messages to cell phones.Commonly a short message is no longer than 70 bytes. I need 20 bytes or more holding information and the rest bytes are for signature provided by ...
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12 views

Does this show the proper results for signing an XML file

I did the following use this (sign) and this (verify) example on MSDN. Here are the results of all this (don't worry, I will delete the below key and generate new keys, on a different system); XML ...
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1answer
71 views

Will PGP signed email be blocked in China?

I generally sign all of my outgoing email with PGP. I don't usually encrypt it because most people I send mail to don't have a public key. Anyway, if I send an unencrypted message with a PGP signature ...
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3answers
93 views

What are you saying when you sign a PGP key?

When you sign a PGP/GPG key, what exactly are you saying to everyone who sees your signature? Are you validating the person, or the email address? To explain what I mean, take the following two ...
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22 views

Is there any way possible that a Digital certificate is issued by admin on wireless channel?

I want that an admin who is working in a wireless environment have to issue digital certificate to the node, who wants to register itself with the network. this certificate will be used by user to ...
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52 views

Verifying the owner of a signing key

I'm using elliptic curve cryptography (curve25519 and ed25519) for key exchange and signing. The signing and key exchange keypairs are independent. I need two users to be able to verify each other's ...
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3answers
125 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 ...
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0answers
70 views

Application Privilege Control in Kaspersky blocks program with no digital signature

I made a small application that displays hello world to the console output and attempted to open it in another computer that had Kaspersky fully updated. When I ran the application, Kaspersky gave a ...
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19 views

Installer digital signature timestamp inconsistency

I just noticed that the digital signature on an old installer EXE is expired (it's LibreOffice from May 2013, and I'm pretty sure it was valid when I installed it). Investigating further, the time ...
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93 views

Are digital signature algorithms subject to the same types of attack as public-key encryption algorithms?

I understand that digital signatures are usually implemented by encrypting a message digest with a private key, decrypting the resulting signature with a public key, and verifying that the message ...
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333 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?
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63 views

Is it Possible to use one commercial SSL Certificate to issue end user certs?

My organization is preparing to purchase some 50 "units" from Symantec, with which we can purchase Verisign SSL certificates of varying authentication levels. Our organization does not have--but ...
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84 views

Typical mistakes when implementing digital signatures?

I am looking for a list of typical mistakes someone can make when implementing digital signatures for a software. And of course why they are mistakes and how an attacker could take advantage of them. ...
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90 views

Digital Signature and man-in-the-middle

While reading this page about Public-Private key encryption, I asked myself a question about digital signature: Alice wants to sign a message for Bob; she uses her private key to sign the message. ...
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1answer
345 views

ADFS: Verify requests from relying party

In ADFS, serveral certificates are used. This is explained (very clearly) on this page: ...
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91 views

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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1answer
59 views

EAP-TLS fragmentation implementation

I am trying to build an EAP-TLS client. The handshake I have to deal with involves receipt of fragmented messages from the RADIUS server. As a part of the client reply, I have to construct a ...
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1answer
154 views

PDF Digital Signature [closed]

I got free certificate from Comodo and installed on my Windows. Now I'm trying to sign PDF document using this certificate, but get message: "signature validity is unknown": Why is this? How I can ...
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1answer
153 views

Testing Digital Signature Verification

I'm testing a system which involves updating a database using files sent from external parties. These files sent from external parties are basically just large flat files to update a database. The ...
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2answers
144 views

PGP/GPG verifying authenticity

My boss recently implemented a new security system related to PGP/GPG. The whole idea behind this is to sign files so that people know from who they came. They don't require us to encrypt them, just ...
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1answer
215 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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40 views

What curve and key length to use in ECDSA with BouncyCastle

I'm developing a client/server system in Java which is not interacting with third party software, so I don't have to worry about compatibility. At a certain point, I need the client and server to ...
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1answer
62 views

Digitally sign all outbound data [closed]

I want to digitally sign all outbound data from my computer. Can someone suggest a way to do this programatically or using some tool? Instead of actually signing the data, I would simply append a ...
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2answers
189 views

Clarifying MITM attacks and Digital Certificate requirement

We are running a Portal application for our client with Payment Gateway integrated. Payment gateway uses SSL as it is suppose to be . The concern for me is that our Portal application does not use ...
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1answer
38 views

Digitally sign all the packets from client machine

If I insist on digitally signing all outgoing packets from my computer, would it affect my browsing experience? I mean if a website doesn't expect me to sign my packets, and still I sign them, can I ...
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3answers
70 views

Public key encryption vs Digital signatures

For same chunk of data, which one is faster? Public key encryption or digital signature? Confidentiality is not important. I am trying to achieve non-repudiation for the communication. Thanks!
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2answers
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Does SMIME differ from TLS, PGP, DMARC signature, or a Portal Encrypted email message in terms of legal non-repudiation?

I'm interested in protecting email messages from NSA-style snooping, but don't want to incur additional legal risk in doing so. In other words, does SMIME encryption and/or signing cause a given ...
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69 views

digitally signing a document [closed]

I've been asked to implement digital signatures for documents at work. I really need to read up more on the matter but several searches didn't make an obvious approach stand out. Main features I ...
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1answer
58 views

Trust on certificate authorities

If I as layman don't err, there are in banking controls, from both internal and national oversights, of the work done by the employees. These are apparently effective, since the details of ...
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25 views

How digital certificate works? [duplicate]

I am trying to understand the digital certificate concept , but I am confused , Below goes my understanding & question, We are using Digital certificate because if Bob & Alice share their ...
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2answers
116 views

RSA-Based Signature Algorithms

From Beginning Cryptography with Java - chapter 4, digital signatures: Signatures are created using the RSA algorithm by applying the RSA algorithm using the private key and then distributing ...
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48 views

Algorithm to Transaction Data Signing

Transaction Data Signing I need an idea to develop a very secure algorithm to authenticate online operations using PHP in the server and an Android app in the user's device. What is the idea? The ...
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1answer
96 views

Why do I have keys of strangers in my GPG keychain?

I'm going though my GPG keychain. I've got a key for a few strangers in my keychain. I don't recall exchanging keys and I'm not sure how the public keys came to be installed in the keychain. I think ...
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3answers
227 views

What part of the CSR is hashed in order to create its signature?

I'd like to change the CSR before it is transferred to the CA without going through the CSR creation process again. To do that I need to know how to calculate the signature of the CSR after I modified ...
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1answer
64 views

Is this signature methodology secure?

I'm working on authentication for my JSON-RPC API and my current working strategy is using signed requests sent via POST over SSL. I'm wondering if anyone can see any vulnerabilities that I haven't ...
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1answer
119 views

Is there an algorithm to generate digitally signed URL links?

Scenario: Alice prepares an URL link to Bob's web service (e.g., http://www.bob.com/sensitiveData/123?login=mallory). Alice gives the URL link to Mallory. Mallory follows the link to trigger an ...