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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How do the processes for digital certificates, signatures and ssl work?

I have been trying to understand how ssl works. Instead of Alice and Bob, lets consider client and server communication. Server has a digital certificate acquired from a CA. It also has public and ...
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1answer
660 views

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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3answers
362 views

DHE exchange and client authentication

If a server has a known public key and a Diffie-Helman exchange is performed and signed by that key, is there any benefit to authenticating the client before establishing a secure channel instead of ...
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1answer
280 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 ...
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1answer
880 views

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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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 ...
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3answers
505 views

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 ...
4
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1answer
109 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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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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3answers
619 views

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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3answers
977 views

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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3answers
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License key / Serial number generator and checker

I need a serial number generator and accompanying checker. I would like to be able to set a salt (and maybe a length). The generator should only produce serial numbers that pass the test of the ...
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4answers
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Why should one not use the same asymmetric key for encryption as they do for signing?

In an answer to a question about RSA and PGP, PulpSpy noted this: It is possible to generate an RSA key pair using GPG (for both encryption and signing -- you should not use the same key for ...
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2answers
153 views

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?
26
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4answers
14k views

How to achieve non-repudiation?

If I have a message that I need to send to another person, how do I achieve non repudiation ? Is digitally signing the message sufficient ?
28
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11answers
1k 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 ...
12
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1answer
341 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 ...
5
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2answers
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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 ...
7
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4answers
656 views

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 ...