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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Is a 512 bit RSA key secure when used temporary?

Is a 512 bit RSA key secure when a new key gets generated and used approximately once a week? The key is only used for signing messages, not for encrypting sensitive data. This is for a system where ...
4
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2answers
769 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 ...
9
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7answers
292 views

Proving running code on a website is unchanged

Can it be proved to the user that the running code behind a website with security related code is the same as published? I'm currently looking at a few new project ideas and one involves secure ...
5
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1answer
299 views

Most efficient key algorithm for a TLS server key?

Let's assume I want to setup a HTTPS service on a modern-but-no-so-speedy x86 server without any form of hardware cryptographic accelerator. Which key algorithm should I choose for the server key in ...
5
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2answers
4k views

When using symmetric key encryption, do we need to sign?

Say we're using a shared key between two parties, that has been distributed using public key encryption, is it still necessary to sign any data that's encrypted using the shared key? Or is it enough ...
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2answers
467 views

Which factors should I consider for devices that accept handwritten digital signatures?

These days many locations ask you to give your signature on a digital signature pad/device. As I am situated in Europe, the EU directive 1999/93/EC seems to regulate it. From what I have found out ...
3
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1answer
2k 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 ...
2
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1answer
248 views

Is the `ssh-agent`'s DSA signature deterministic?

In my hopes to use ssh-agent to generate a signature as password I implicitly assumed a deterministic signature. DSA is however supposed to take random value k for signing. However that randomness is ...
5
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3answers
569 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
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1answer
973 views

How to verify the signature in an iOS Passbook pass?

The Passbook application in the new iOS6 keeps track of movie tickets, coupons, and other 'passes' for you, and the passes themselves are loaded onto the user's device via file packages with the ...
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3answers
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rsa encrypted hash == rsa signature

$ echo -n "1327943823" > test_ok.txt $ openssl dgst -sha1 -binary -out test_ok.sha1 test_ok.txt $ echo "GURbsl4CFPCG83RCZxsEpoRleXicXQhH1OC4Fk77b7EMj2g8aHUhD/L+sm ...
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6answers
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Why not RSA-encrypt the entire document?

I have recently learned of a way for person B to verify that a document sent from person A is indeed from person A. Person A gives Person B his public RSA key. This must be done reliably. Person A ...
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2answers
1k views

Revoked certificate validation using past times

I'm working on XAdES implementation for Java, as such I require cryptographic implementation to be able to verify certificates in the past. Unfortunately I have problems verifying revoked ...
5
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5answers
234 views

Is there any security value of creatively naming folders containing sensitive files?

A friend of mine asked me if he could sign his tax returns without printing them out. While helping him, he insisted on naming the folder containing images of his signature and initials a completely ...
1
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0answers
254 views

Verifying Authenticode signed executables and DLLs using OpenSSL API [closed]

I have installed openssl and now the rsa_test.c is running fine. What I want to do is: Open any exe or dll digital certificate. Extract the Thumbprint and PublicKey. The public key contains the ...
3
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2answers
623 views

Distributed XAdES-X and XAdES-A signatures over multiple documents

As the standard is not completely clear in this matter, I'm trying to found out if the XAdES standard (ETSI TS 101 903 v1.4.2) describes distributed case in which the SigAndRefsTimeStamp element or ...
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2answers
170 views

How does a code signing vender charge for creating certificate chains?

I have a question about creating digital signatures for pdf files. I want to have a certificate for my company and have children certificates as many as the number of company's employees who can ...
3
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2answers
339 views

Reusing HMAC state for multiple messages

I have a secret key k and message m. I send m || HMAC(m, k) to some other party, who can verify the integrity of m, assuming that they know k. Suppose I have multiple messages m1, m2, and so on. ...
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3answers
1k views

Digital Signature and Verification?

AFAIK , When Alice wants to write a message to Bob -- she uses Bob's public key and encrypt the message - and then Bob - using his private key - use to decrypt it. So public key is used to decrypt ...
4
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1answer
79 views

Standards for CA cert revocation and time-constrained cryptographic algorithm parameters

I'm working on software that will be in use for foreseeable future (15 years+) that will need to validate XAdES-A signatures (long term archival, similar to PAdES-A, but for XML). That means, it will ...
5
votes
2answers
859 views

What are the real-time applications of long term digital signature with timestamp

I want to know the real time applications that uses digital signatures with timestamps. Specially I am interested to know the applications where we can trust an old signed document which is now ...
3
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3answers
2k views

How to sign & timestamp log or zip files?

I think I can easily sign the files however I also need a timestamp from 3rd party vendor. I want to digitally sign + stamp log files including DHCP & mail because of laws here. UPDATE: I found ...
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2answers
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Signed request vs HTTP digest auth for API authentication?

By signed request I mean something like this (simplified example): Client creates a sig in his request: $sig = hash('sha256', $api_key.$data); which generates 7409ur0k0asidjko2j for example. He then ...
12
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3answers
583 views

Can signing too much compromise a private key?

Can a collection of many messages signed with the same private key be abused to either forge signatures so some (but not all possible) messages, or even worse to reconstruct that private key with less ...
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1answer
297 views

Can I export my digital certificate to this emtec usb

It is said here http://www.emtec-international.com/sites/default/files/s530_aes_en_0.pdf 2048 bit RSA module: ready for PKI application SHA256 data hashing: ready for digital signature Does it ...
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3answers
10k views

What is the difference between an electronic signature and a digital signature

From Wikipedia: An electronic signature, or e-signature, is any electronic means that indicates either that a person adopts the contents of an electronic message, or more broadly that the ...
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1answer
314 views

Signature and Timestamp for Long Term Document Archival Question

I have a PDF document intended for long-term (many years, maybe decades) archival which I would like to digitally sign with my personal certificate to ensure its integrity. As far as I understand, I ...
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1answer
510 views

Purpose and Uses of Root SSL Certificates

I'm trying to wrap my head around the technical inner-workings of SSL and one of the last things I'm choking with is the concept of "root" SSL certificates (as opposed to "non-root"?!?). When and ...
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2answers
503 views

Request/Creating a Code Signing Certificate

I have need for a code signing certificate which is trusted by a CA in the windows domain. How do I request/create this certificate? Do I have to request a code signing certificate on the ...
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8answers
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Why do people still use/recommend MD5 if it is cracked since 1996?

It's still commonly recommended way of hashing passwords, even if it's insecurity had been proven in 1996 Therefore we suggest that in the future MD5 should no longer be implemented in ...
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2answers
279 views

Using digital signatures to identify users

Consider the following requirement: Bob should be able to verify that a payment request came from Alice. The above is in simple terms the basic idea, however, in reality Alice would be user A of ...
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2answers
703 views

Digital signature with partial recovery

I'm having problems understanding what is meant by "digital signature with partial recovery". I found from Google that digital signature with recovery should mean that the message is recoverable from ...
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3answers
368 views

Why do credit cards not use digital certificates?

Asymmetric encryption and digital certificates are used all over in the IT world to verify authenticity and prevent forgeries. And it works great. Why do credit cards not use some form of ...
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1answer
629 views

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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2answers
728 views

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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3answers
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Does GPG key expiration add to security?

I've created a new GPG key to sign a software package in a source repository with an expiration date three years from now. It seemed like a good security measure because if the key is compromised or ...
17
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1answer
15k views

What is the actual value of a certificate fingerprint?

In a x509 digital certificate there is a "certificate fingerprint" section. It contains md5, sha1 and sha256. How are these obtained, and during the SSL connection, how are these values checked for?
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votes
1answer
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PKCS7 encoding in Java without external libs like BouncyCastle etc

I am working on signing and encoding of CMS/PKCS#7 messages (something similar to C# SignedCms). I have x509certificate from the keystore, rsa private key, ContentInfo. ContentType is "oidPkcs7Data". ...
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1answer
352 views

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 ...
2
votes
1answer
728 views

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 ...
7
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2answers
788 views

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 ...
3
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1answer
1k views

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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4answers
1k 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 ...
9
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3answers
5k views

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 ...
4
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1answer
137 views

Are the SSL Digital Security Certificates based on Kerberos Network Security Protocol

I just want to know if digital certificates use the kerberos session key algorithm.
5
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1answer
24k views

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 ...
3
votes
2answers
270 views

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 ...
7
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1answer
489 views

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 ...
4
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1answer
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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 ...
3
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2answers
391 views

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 ...