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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Corporate PKI - SHA1 deprecation

Here is the context. Suppose you have a corporate PKI with : AC_Root (offline in safe store - SHA1 signature) SubRootA and SubrootB (offline in safe store - SHA1 signature) SubSubRootC, SubSubRootD, ...
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80 views

Sign java jars for security [closed]

We have an enterprise system that utilizes many in house jars, java applications, to run on a centos 7 linux system. How do I go about achieving the following in order of importance: Only signed ...
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1answer
125 views

Digital signatures and weak hash functions

There was this question in last year's exam. The teacher claims that answer b) (in boldface below) is correct. Attacks are constantly being performed on digital signatures which use weak hash ...
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2answers
394 views

Verify digital signature without key public key in signature

When receiving emails, I sometimes see the following: -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 I found an integer overflow in PHP, in the conversation of dates to "Julian Day Count" function. ...
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1answer
153 views

If you can break this authentication system then you can break into my house

I'll preface this by saying I know approximately 0 about cyber-sec I've made a server that will allow smart phones to act as a remote control for my house (eg turn lights on/off and unlock doors). ...
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8answers
589 views

Authencity of information displayed on an untrusted device

Suppose I have a (bluetooth/usb) device which needs to displays information on an external pc/phone. Is there a simple and effective method to garantuee that the information displayed hasn't been ...
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1answer
90 views

Multi-Function SSL Digital Certificate

Is there a problem with using a single SSL certificate for both SSL/TLS/HTTPS communication as well as to sign (external) digital timestamp certificates? Other than the obvious: if one key is ...
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1answer
672 views

Server-based PDF Signing using HSM

I have some question about server side pdf signing using network-attached hardware security module. my first question is: what is PDF Signing Certificate? Certificates are public keys, how a ...
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2answers
227 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 ...
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2answers
665 views

Installing and updating a CA certificate on a client

I am trying to implement a system where a client can download application packages from a server to install/update them on the client. I suppose that the client is something like a platform on an ...
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2answers
225 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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2answers
204 views

Public key authentication: what gets signed?

I've just started reading about SSH and how it's used for authentication. From this website, it says: The private key is able to generate signatures. A signature created using your private key ...
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11answers
2k views

Does hashing a file from an unsigned website give a false sense of security?

Consider this. Many websites with software downloads also make available MD5 or SHA1 hashes, for users to verify the integrity of the downloaded files. However, few of these sites actually use HTTPS ...
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2answers
9k views

Why are hand-written signatures still so commonly used?

Why are hand-written signatures still so commonly used? Can they actually prove anything? Two assumptions: If anyone wants to forge my signature I'm sure they will be able to do it. Even my own ...
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1answer
165 views

Are there theoretical attacks against ECC Digital Signatures?

I was asked to do a research about attacks on various digital signature schemes. There is one thing that bothers me for which I could not find a direct answer. For digital signatures that are based ...
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3answers
789 views

How can I prove that I wrote a certain blog post?

I would like to be able to prove that I wrote the article that resides at a given URL on someone else's blog. Is there a way that I can do this with public key cryptography? I know a bit about the ...
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2answers
273 views

SHA1 - S/MIME and CRL validity after deprecation?

In an internal PKI using SHA1 for hashing, will S/MIME signature and CRL/ARL signature be considered invalid in the next few years (SHA1 Deprecation) ? End certificates can be revoked, CA ...
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2answers
113 views

Certificates - What about signing again Intermediate CA certificates?

I an thinking about this issue and it is hard to estimate technical impacts. For any relevant reasons, one want to modify one the x509 field of an intermediate CA. This intermediate CA was signed by ...
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1answer
134 views

PKI - Security concerns when changing a certificate hash algorithm

Suppose I want to change the hash algorithm used for a certificate signature (ex: SHA1 to SHA2). Is it better to revoke the previous certificate and issue a new one with expected hash algorithm ? Or ...
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1answer
853 views

Is there a way to verify a signed XML in Java

.NET has this great way to sign and then verify the signature of an XML file. Is there a way in Java to verify an XML file that .NET has signed this way? thanks - dave
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2answers
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TLS - Are signatures still needed?

The story: I'm currently writing a web service that allows for communications to be made remotely via TCP/IP. I first thought about signing each packet using HMAC-SHA1 with a password, appending the ...
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1answer
209 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
176 views

What is 0xXXXXXXXX.asc.sig and how can I generate this?

When I am exchanging PGP keys with someone, I receive the regular 0xXXXXXXXX.asc file and regularly receive a file called 0xXXXXXXXX.asc.sig. What is this file? How can I generate one and send it ...
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1answer
333 views

Use of safe prime in RSA digital signature scheme

For the RSA digital signature scheme , Alice has a pair of public and private keys as denoted by Public key : (e,n) Private key : (d,n) Assuming Alice wants to send a message M to Bob , she would ...
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1answer
274 views

Using salt or secret for Hmac

I'm working on a web API. We are going to use Hmac256 for signature hashing. From what I can gather, the secret is a key used to initialize the hash algorithm (ie to generate a random number). The ...
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1answer
123 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
3k views

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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1answer
83 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
179 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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1answer
73 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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2answers
200 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
154 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 ...
2
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1answer
153 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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1answer
167 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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3answers
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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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1answer
221 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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2answers
753 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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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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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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452 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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2answers
574 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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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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1answer
174 views

IKEv2: Why is it important “that each side sign the other side's nonce”

I am currently diging deep into the IKEv2 protocol. In the description of the Authentication (RFC5996, p. 48), the following statement is given: "It is critical to the security of the exchange that ...
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2answers
1k views

Does Authenticode still work offline and with a “fake” certificate

Here's our story: We're developing some software (written in C#/.NET) and we're already signing the assemblies with strong names, I do this in Visual Studio with a pfx file that is protected by a ...
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2answers
196 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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3answers
407 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
293 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 ...
0
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1answer
848 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
530 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
220 views

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 ...