Asymmetric cryptography, or public-key cryptography, is the foundation of security protocols that do not require shared secrets.

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Which host key algorithm is best to use for SSH?

When you first connect to an SSH server that is not contained inside your known_hosts file your SSH client displays the fingerprint of the public key that the server gave. I found from this question ...
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24 views

Which symmetric encryption method does PGP use for its hybrid-method?

I'm doing some research on PGP for a class-assignment. I've tried to find out which exact implementation PGP uses for its symmetric encryption part. Finding out about RSA as the asymmetric one was ...
0
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1answer
29 views

Would logging into Chase bank website be an example of Asymmetric cryptography? [closed]

Also anyone who is familiar with Outlook, is sending digital signed messages a process of Asymmetric cryptography? Since it uses a public key and requires your Smartcard PIN before you can actually ...
4
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1answer
113 views

ProtonMail: Would it not be much better if each user had their own private key?

ProtonMail keeps the encrypted private keys of all their users in their servers. The mailbox password for each user decrypts this private key, which is known only to that user. Would it not actually ...
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4answers
70 views

How is the private key kept secret in digital signatures?

A digital signature is verified using an algorithm that takes three inputs: the message, the digital signature (message encrypted with private key)* and the public key. If the public key is used to ...
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1answer
47 views

Brute force symmetric knowing asymmetric

Lets say message A is encrypted with symmetric encryption. BUT before encrypting the message, it is asymmetrically encrypted (let's say to implement VPN ...). Now if a man in the middle captures the ...
2
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2answers
57 views

Asymmetric key encryption that can have a public decryption key, but encryption key cannot be computed from that [duplicate]

Is there a way where I can distribute a public decryption key, but the encryption key cannot be computed from that key, so that anyone who reads one of my encrypted message, he/she can be quite sure ...
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2answers
108 views

Suggestion on asymmetric (hybrid encryption) encryption for big file

We will be using following commands to encrypt to firmware file at server and that will be decrypted on the embedded board using decryption command mentioned below, Following command will be used to ...
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0answers
37 views

ISO 9564 Approved Encryption Algorithms for PIN, why symmetric block ciphers?

I am currently researching best practices in designing a potential PIN management solution for a financial services application and began looking into ISO 9564 as a source of requirements. One of the ...
4
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1answer
114 views

Ways to generate symmetric and asymmetric keys

We are using Beaglebone Black based custom board, and want to use hybrid encryption for encrypting firmware file, i.e. symmetric for encryption big firmware file and asymmetric for encrypting ...
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2answers
72 views

How does digital signature algorithms work in a private / public key environment?

From the Wikipedia page on the subject, I get, on a theoretical level, how the process of encrypting and decrypting a message works. The article states that: In a public-key encryption system, any ...
0
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1answer
115 views

Public Key Encryption vs HSM for storing encryption keys

Let's say I have sensitive data in the database server that needs to be encrypted (i.e emails, etc..) and I want to make sure that in the event that the server is compromised, the attacker shouldn't ...
-4
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1answer
101 views

Preventing someone to generate a public key from a private one? [closed]

From what I read, encryption algorithms such as RSA permits to generate the public key from the private one. Long story short, for a thesis I'm writing, I thought to solve a security issue with users ...
2
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2answers
65 views

Way to combine encrypted tar and encrypted symmetric key with which tar was encrypted?

We are using Beaglebone Black (AM335x) based custom board, so for firmware upgrades of the board we will be using an encrypted firmware image. As you would have already guessed, we will be using ...
0
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0answers
33 views

Use MDC to provide origin authentication for public key encryption?

Why can't we use an manipultation detection code (MDC) to provide origin authentication when using public-key encryption?
3
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0answers
80 views

Security of the shared secret key for a smart meter (Linky) [closed]

Reading the specs of a new electricity smart meter (called Linky in France), I was surprised about the chosen encryption method (128 bits symmetric key AES), based on a single secret key (called CCC ...
0
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1answer
115 views

Why doesn't my manual RSA key exchange example work?

I'm trying to "manually" compute how the premaster_secret is computed using the RSA key exchange in TLS 1.2, but can't manage to make numbers meet. I am using Scapy SSL to generate a TLS session: I ...
2
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1answer
123 views

What is the difference between a digital signature and whole message encryption?

I am newbie in information security I am trying to understand the difference between a digital signature and encryption of a message. Lets consider simple example of email message. I understand how ...
0
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1answer
115 views

How to verify the signature value in a SSL certificate?

According to RFC 3280 a certificate's basic syntax is Sequence := { tbsCertificate signatureAlgorithm signatureValue } In tbsCertificate, SubjectPublicKey is the public key of the ...
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3answers
1k views

What are the disadvantages of using public key cryptography when encrypting files? [duplicate]

I am wanting to encrypt a file with my public key, my friend told me that this is not a good idea but did not explain why. Can someone explain please.
2
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1answer
49 views

What does it mean to sign a public key and what's wrong with signing someone else's key?

I just stumbled upon this comic and I'm not sure if I understand what's going on. I googled and I figured that somehow people can sign other people's public keys and then they that person is genuine. ...
0
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0answers
76 views

For multiple clients it's better symmetric or assymetric encryption?

I'm a newbie in the encryption world so I'm here for asking which is the best solution between Symmetric and Asymmetric encryption. In our use cases, we have multiple clients that must be ...
7
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5answers
221 views

Secure application data transmission via SMS channel

There are mobile banking applications that use SMS channel to communicate with their server. Some of them offer both internet and sms channels which the customer gets to choose from. While there's ...
0
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1answer
68 views

how is public key being exchanged in asymmetric cryptography?

I understand that exchanging public key between parties is challenging task in asymmetric cryptography.Can someone help me understand how it is achieved?
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2answers
111 views

How are private and public keys different?

While reading about DKIM I saw that the sender's private key is used to encrypt a hash, later decrypted by the recipient using the sender's public key. This is exactly the other way compared to ...
0
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2answers
112 views

Password based Asymmetric Key generation

I am looking for a password based key derivation scheme that results in an asymmetric key pair. I have worked with PBKDF and its variants but could not come up with any way of generating a key pair. I ...
0
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1answer
66 views

How to make a good choice between Symmetric and Asymmetric [closed]

Here and there and read a lot of articles and blog posts titled "Difference Between Symmetric Cryptography and Asymmetric Cryptography". But inside of them they are answered "What is Symmetric ...
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1answer
84 views

What happens if two parties have the same public key? [closed]

What would happen if I get a public key that someone else already has? Isn't the security very weak in that case?
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5answers
158 views

Is it secure to ship public key with license file?

I've implemented a licensing client and server for our web-applications. Currently there is only one way for licensing an app, user should manually upload the license file using specified form and ...
0
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0answers
59 views

stream cipher & e-banking

As I read on internet, I ran into these two question. Yet, I thought about it but still don’t know how to tackle it. May I have your help? (a) During an e-banking transfer the bank uses a stream ...
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3answers
183 views

Public Key Encryption instead of passwords

As an alternative to using passwords, customers could be provided with individual asymmetric-encryption key pairs (i.e. a private key with associated public key), which could be used to validate their ...
0
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2answers
70 views

Asymmetric Encryption for Multiple Recipients?

Let's assume an arbitrary group of people who hold a key pair and who make their public key online accessible. Let X, A, B and C be arbitrary people from that group. Now X wants to encrypt a message ...
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votes
1answer
60 views

ssl - How is asymetric algorithm used in SSL/TLS?

Okay I have read the questions here on how SSL works, but they all focus on symmetric encryption. But I have configured Apache WebServer to use RSA for SSL using the openSSL tool. Now my question is ...
43
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4answers
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Why is key exchange necessary at all?

Let's say "Alice" and "Bob" want to communicate with each other over an insecure network. Using Diffie–Hellman key exchange, they can get the same symmetric key at last. However, as I understand, ...
2
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1answer
45 views

Use asymmetric encryption once to exchange symmetric key

I'm developing a json API that should be able to handle a huge amount of clients. To make this work I need to reduce the overhead as far as possible. One of the ideas I have is to use https only in ...
0
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3answers
155 views

In message signing, is the digest encrypted with a generated symmetric key or with the sender's private key?

I understand the encryption process uses a generated symmetric key to encrypt a message, and then encrypts the symmetric key with the receiver's public key before it is sent across the wire. This ...
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0answers
53 views

Purpose of MAC when encrypting? [duplicate]

Really basic question, but what is the purpose of using a MAC/HMAC when you are encrypting using a symmetric key algorithm? It is my understanding that the purpose of a MAC is to authenticate the ...
1
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0answers
66 views

Curve25519xsalsa20poly1305 key derivation

I'm working on batch-encryption of files, for a small project of mine. The files are stored encrypted on a removable drive, and the keys are stored on a trustful server. For enhanced safety, I'd like ...
0
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1answer
83 views

In Asymmetric cryptography, is the number of Private Keys limited?

My question is a bit of a leading question, because I assume that the number of Private Keys is a finite number. However, it is possible that the number is such a large number that it would ...
1
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1answer
69 views

Need asymmetric encryption(not signing) where server encrypts and client decrypts

So I'm trying to build a licensing server, where the licenses of the applications need to be checked when logging in or when the application gets used. But some of those application work offline most ...
1
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2answers
231 views

Difference between KMS and PKI

While the PKI System deal with digital certificates life cycle and Key Management System (KMS) deal with keys life cycle. What is the the fundamental difference between them? Is it possible to ...
3
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2answers
238 views

Why can I sign but not encrypt?

-edit- After following a chain of links from this question I see this is similar/duplicate of Why should one not use the same asymmetric key for encryption as they do for signing? but this question ...
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1answer
106 views

Cloud-based IM protocols / services saving messages encrypted on server which is decryptable only by user? [closed]

I am looking for a cloud-based (i.e. not end-to-end) secure IM protocol or service. The first one comes to my mind is telegram. Here is a quote from telegram's privacy policy: Cloud Chats ...
0
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1answer
314 views

RSA: same symbols in plaintext give same symbols ciphertext?

I just started studying Information Security, but I just ran this program: http://www.sanfoundry.com/cpp-program-implement-rsa-algorithm/ and faced this strange thing. For small keys (don't try to ...
2
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1answer
250 views

SQL Server Asymmetric Encryption Keys

I have used SQL Server database with data to be encrypted and I will use symmetric key for encryption and will encrypt it by asymmetric key now comes the question how to give user permission to ...
7
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2answers
263 views

Can symmetric key cryptography provide identification?

I understand that PKI uses digital certificates to link a public key to an entity, but is there anything similar for symmetric cryptography. If, theoretically, PKI didn't exist, how do you know you ...
3
votes
1answer
161 views

Is this symetric or asymetric encryption?

I’m at the beginning of my journey into the world of security. I am reading about the most fundamentals topics and I have encountered something unusual that has thrown me. The Conundrum: I have come ...
2
votes
1answer
223 views

How does this encrypted webmails works?

In the last days I was looking on Tutanota, ProtonMail, LavaBoom, and others webmails that promise to respect users privacy. For all those, the one I most liked was Tutanota. I did few tests with ...
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3answers
1k views

ProtonMail security concerns

This TED talk brought me here. First of all, to those who created ProtonMail: Nice job!!. Regardless of what people say, it's definitely a big step forward from tradition options like Hotmail, Gmail ...
3
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1answer
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difference between public key and host key and security of host key

In SSH, what is the difference between host key and public key. Public key I believe that is part of private/public key pair, so, that anything sent by server(encrypted using private) can be ...