0
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0answers
24 views

How digital certificate works? [duplicate]

I am trying to understand the digital certificate concept , but I am confused , Below goes my understanding & question, We are using Digital certificate because if Bob & Alice share their ...
0
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0answers
36 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 ...
2
votes
1answer
196 views

Which mail clients support PGP/MIME - is there an overview? [closed]

Does anyone know if there is a current overview (I only found ones from before 2006) which MUAs (mail clients) do support PGP/MIME? I wonder whether there still exist issues like "Outlook Express ...
2
votes
3answers
243 views

Can a zero knowledge proof of voting be made using a trusted auth server (without client side crypto)?

Questions: Can one implement a secure voting system having all the features described below? e.g. without disclosing any individual's vote to the government server (or the third party), preserving ...
3
votes
3answers
325 views

Is there an attack that can modify ciphertext while still allowing it to be decrypted?

Is there any way an encrypted file using AES-256 could be modified without alerting the file owner, ie., so it can still be decrypted with the same key? I know that without an initialization vector ...
1
vote
0answers
181 views

Implementing OAuth flow in JavaScript

I am making a custom auth flow for the application. It is inspired by OAuth 2.0. Dev sends user to an auth page on my domain, passing callback_url and api_id. I redirect user to callback_url, passing ...
-1
votes
4answers
209 views

Is it possible to digitally sign information with a password?

I'm creating a cloud storage service and need to have the ability to provide reliable security for clients. In my previous question, I used a different schematic and said I would post a new question. ...
1
vote
0answers
105 views

Techniques for web-user communication across an untrusted server

I'm designing a web-based notification framework (i.e. a user can subscribe to updates from a service or another user) where communication between users is encrypted. User-to-user communication on ...
3
votes
1answer
136 views

How signature validation would be checked on server side?

Sorry, It may be possible that few things are repeated in my question. I have gone through some documentation/discussion signing an API request and twitter signature documentation As per the ...
0
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2answers
414 views

Using a Common Private Key for Digital Signatures

I have a mobile application and a server. The mobile application communicates with the server through a web services framework via SSL. The mobile application allows customers to pay for ...
3
votes
1answer
361 views

GnuPG/KGpg Sign PGP Key - Sign User ID : What is the difference?

What is the difference between signing a user ID and a whole Key ? Which behavior is the best as to signing user IDs and Keys ? How and when to use "Local signatures" (non exportable) ? (I was told ...
3
votes
1answer
526 views

Can you make a digital signature using the receiver's public key?

My question is, can you make a digital signature using the receiver's public key and then have the receiver verify the signature using his private key? I always thought that in order to create a ...
1
vote
1answer
235 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 ...
2
votes
1answer
738 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 ...
1
vote
4answers
311 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 ...
1
vote
1answer
312 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
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1answer
276 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
3answers
1k 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 ...
14
votes
6answers
1k 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 ...
5
votes
3answers
654 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 ...
5
votes
3answers
3k 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 ...
5
votes
1answer
16k 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 ...
6
votes
1answer
441 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 ...
9
votes
5answers
8k views

What does “key with length of x bits” mean?

I'd like to know what it means to say "the cryptosystem C uses keys with a length of x bits". I do not understand what the bits length means... doesn't it depend on the encoding? The same word encodes ...
19
votes
2answers
2k 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
1answer
104 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 ...
8
votes
3answers
595 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 ...
40
votes
4answers
8k views

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 ...
12
votes
1answer
328 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 ...