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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Best Practices for Storing Digital Certificate

I'm building an application where certain sensitive files need to be digitally signed before being stored in the file system using ASN.1 encoding, so they can be verified against a digital certificate ...
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Most widespread use of PGP after 20 years

Phil Zimmerman released PGP (Pretty Good Privacy) on June 5, 1991. As we examine the legacy of that far-sighted and brave act 20 years later, what are the most widespread and helpful uses of PGP ...
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Time needed to generate an RSA signature of a document

How does the length of the RSA key and the size of the document affect the time it takes to sign a document using SHA-1 and RSA? I used CrypTool to check it, but the time does not appear to be larger ...
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How to use OpenSSL generated keys in Java?

I have my pair of Public and Private keys and my certificate. Those where created in OpenSSL (why? because I was asked to do it in OpenSSL). Now I want to use those things to make a Java app that ...
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Does signing my e-mail with DKIM imply non-repudiation for all my users?

Since a few weeks I have set up my google apps domain to use DKIM for all outgoing mail. Does this mean that everyone that is in possession of a copy of the message can verify that it really ...
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Public key length

I was wondering if there was (and I hope there is) a standard for public key size for ECDH (Elliptic Curve Diffie-Hellman) and ECDSA (Elliptic Curve Digital Signature Algorithm) for every curve type ...
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DRY API Authentication Design Between Services

I am creating an API service that is going to require authentication. this will be the first part of a project that will include a front-end service for my website, and also open up the api for 3rd ...
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Enforce Code/Script Signing

I have both a couple of X.509 Code Signing certificates and a GPG keypair that I can use to sign against code I run on my VPS. Every now and again I write code for iOS, OS X and Windows and always ...
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encode der with openssl

When you issue openssl dgst -sign key <file it follows the PKCS#1 standard to generate a digital signature. hash file with some hash digest function encode the hashed value in DER format, ...
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What good, standard digital signature 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. For example, imagine an election administrator who wants to ...
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Can I use a private key as a public key and vice versa?

I have code to encrypt data using a public key and decrypt it using a private key. This is useful when a client wants to send data to a server and know that only the server can decrypt it. But say I ...
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security and the well constructed Qt plugin

"All you'd have to do is build a plugin and you could completely pwn the software." I'm building an application using plugins. I think all you have to do is build a plugin and copy it into the ...
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How to Get and Set Digital Signatures with FDA 21 CFR Part 11 Standards

How do I get and set digital signatures with the 21 CFR part 11 standards as defined by the Food&Drug Administration of the USA?
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OpenPGP Encryption / Decryption Process Using GnuPG

I want to know if my method of encryption can ensure the security of my data if my database was hacked as well as the authenticity of the data I am decrypting. I am using GnuPG's implementation of the ...
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Null content digitally signed message

IA technical specification I'm following requires me to send: The Digital Signature must be in the form of a null content Digitally Signed message (i.e. a PKCS#7 object containing the signature ...
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Securely signing a container package

I have a desktop application that uses a kind of package format to load a blob and do something with it. To ensure the authenticity of the blob, I would like to add a digital signature. I researched ...
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What is gained by hashing the last block on-device?

Recently I encountered the notion of "hashing the last block on-device". It means that when computing a digital signature, the hash that serves as input for the actual signature computation is not to ...
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What kind of certificate do I need to be able to make and sign my own digital signing certicates?

At build time for a program, I would like to generate a new key pair, and create a certificate that will be embedded (securely) into the program. The purpose of the key pair is to digitally sign an ...
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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 ...
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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 ...
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Is there a way to accept signed requests without storing client's password in plaintext?

We are developing REST Web service. We will give Identifier and Secret string to each of our REST clients. When doing requests, clients will authenticate themselves using HMAC algorithm (they will ...
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What are the advantages of sequential signing

What the advantage of sequentialy signing a document? That means signing a document by two people in a sequential manner?
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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 ...
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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 ...