A digital signature (not to be confused with a digital certificate) is an electronic signature that can be used to authenticate the identity of the sender of a message or the signer of a document, and possibly to ensure that the original content of the message or document that has been sent is ...
13
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7answers
3k views
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 ...
0
votes
1answer
86 views
How secure is my private key in the Windows Digital Certificate store?
Many files we download don't have digital signatures. Files may get infected or someone may intentionally modify them on our hard disk.
So I wrote a simple file hashing program in c# that creates a ...
5
votes
5answers
153 views
A standard way to manually add a digital signature to a pdf file?
I've created a few certificates to use myself, but I find myself stumped when it comes to creating a certificate which contains a digital signature. First, how would I go about creating a standard ...
2
votes
1answer
78 views
The security of sending emails with SPF/DKIM, but not signed
We're using an email sending service (fairly known) to send our emails. We made DNS changes so that emails going through them would pass SPF and DKIM.
A few days ago we noticed that they allow any ...
2
votes
1answer
78 views
is pkcs#7 suitable for signing and encrypting zip files?
I'm looking to protect zip files that I will be regularly sending to a 3rd party.
I need to ensure strong confidentiality and non-repudation. I would like signing/encryption to be based on ...
3
votes
1answer
146 views
how to specify pkcs#7 requirements for a third party you are exchanging data with?
I am looking to use PKCS#7 to sign and encrypt data (offline batch data files) that are exchanged with a 3rd party.
I need to write an interface specification for the 3rd party so that they can ...
4
votes
1answer
47 views
How do I build a secure signing mechanism on top of HMAC
Say we have a system with strong shared keys (not passphrases), and we're trying to sign messages sent by the server that will be visible to an attacker. E.g. storing session state in a signed cookie.
...
0
votes
1answer
41 views
What is closed system esignature?
I need to find a solution for one of my clients who is asking me to implement a esignature solution.
I was thinking of suggesting some solutions like DocuSign or EchoSign.
But recently my client ...
1
vote
4answers
99 views
certificate usage for signing and encryption
I have a question for basic operating with certificates in emails and pdfs. Im familiar with public key cryptography.
The scenario:
In my scenario I want to send a confidential email to a person A ...
0
votes
1answer
95 views
Where is RSA Digital signature used in the online banking world?
When i do online banking, i sign my digital transaction with a digipass. Ive been told that it uses a RSA-based digital signature scheme. But an rsa digital signature (1024 bit for the modulus) is a ...
4
votes
2answers
111 views
What asymetric scheme provides the shortest signature, while being secure?
I've had a look at several signature schemes (DSA, ECDSA for the most common ones), and am wondering about whether there exist a scheme that would have the following properties :
Be asymmetric (one ...
3
votes
2answers
108 views
what is the difference between a mac and a digital signiture
I understand that a MAC algorithm takes a message and a private key as input and hashes them to a value. I understand that senders and receivers often use MACs to authenticate a message and check the ...
0
votes
1answer
48 views
Does DSA need padding?
So i read on wikipedia that digital signatures need padding (like PSS) and i know this is true for RSA.
But know i ask myself does DSA also need padding?
1
vote
1answer
92 views
PKCS#7 message constructed by our code, any weaknesses in the output?
We have this as the PKCS#7 encrypted message. We would like to open this up for review and analysis here, for people to poke holes. This sample is generated via test certificates and keys. The concern ...
5
votes
1answer
5k views
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".
...
7
votes
7answers
205 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 ...
0
votes
1answer
38 views
How esignature verification process work?
I have a web application in which the users will be signing an html report. I know how the digital signature authentication works. But here the user will literally be signing the document (So, Should ...
21
votes
4answers
5k 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 ?
5
votes
3answers
350 views
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 ...
16
votes
9answers
580 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 ...
4
votes
1answer
143 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 ...
3
votes
2answers
1k 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 ...
5
votes
1answer
181 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 ...
3
votes
2answers
320 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 ...
12
votes
2answers
326 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 ...
4
votes
2answers
723 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 ...
5
votes
3answers
239 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 ...
1
vote
1answer
410 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
votes
1answer
126 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 ...
2
votes
1answer
229 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 ...
2
votes
3answers
350 views
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
...
6
votes
4answers
4k views
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 ...
2
votes
2answers
254 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 ...
3
votes
5answers
181 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 ...
12
votes
6answers
736 views
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 ...
1
vote
0answers
131 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
votes
2answers
189 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 ...
1
vote
2answers
95 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
votes
2answers
151 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. ...
5
votes
3answers
236 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
votes
1answer
56 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 ...
12
votes
2answers
389 views
Digital Certificate deployment: using two certs for each user?
At a large enterprise environment I have come across a deployment approach for Digital Certificates where each user is issued two (2) key pairs:
One for signing documents, emails, etc. that is ...
3
votes
2answers
231 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 ...
2
votes
3answers
482 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 ...
1
vote
1answer
154 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 ...
3
votes
2answers
419 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 ...
1
vote
2answers
337 views
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 ...
8
votes
3answers
282 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 ...
-1
votes
2answers
224 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 ...
0
votes
1answer
95 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 ...
