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Questions tagged [rsa]

RSA is a common public key algorithm, which can be used for encryption and signature. It is a core component of most the security protocols used on the Internet, including the SSL/TLS protocol suite.

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Is GPG's AES encryption that much stronger than its RSA headers? [duplicate]

Correct me if I'm wrong at any point of this questino. I understand that AES is a lot cheaper to compute than RSA (or any form of asymmetric encryption) and that that is why GPG and similar programs (...
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Private RSA vs Openssh key on Cygwin [migrated]

When I generate a key with Cygwin I get a: -----BEGIN OPENSSH PRIVATE KEY----- but I need a: -----BEGIN RSA PRIVATE KEY----- (2048) I use the command: >ssh-keygen -t rsa -b 2048 How do I ...
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AES, RSA, ECC Key size

It is generally said that 2048-bit RSA keys are roughly equivalent to 128-bit symmetric keys and 2048-bit RSA keys are "sufficient for commercial use until around the year 2030" (https://security....
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SSL/TLS and PKCS#1-1.5 Encoding - Why?

I read about SSL (version 3.0) and that the PreMasterSecret (pms) is encoded with PKCS#1-1.5 before the client encrypts it with the given public RSA key and sends the encryption to the server. So the ...
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HTTP body E2E encryption protocol

I have 2 servers that communicate each other in HTTP and they are both behind an API gateway. Between the servers and their API gateways the communication is in HTTPS with mutual authentication using ...
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Sending Private Keys, does it make sense?

There's some logic that I'm not following whenever my organization sets up VMs for SSH access. Perhaps someone can help me understand. Our process is currently as follows Generate Keypair on Linux ...
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How to generate the most secure private key? [closed]

I need to generate the most secure private key. Usually I use a command: openssl genrsa -des3 -out mykey.key 2048 Is triple DES secure enough? Is 2048 large enough? Are there any other ways to ...
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More clarity on Certificate, public key, hash

I'm new to this certificate and public keys. So I've a certificate. I exported as .pem. I opened it in textEdit and it looks like the below. I've used below command to see what this certificate ...
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Can I use OpenSSL to generate a key from asn1 configuration file without specifying the modular multiplicative inverse q^-1 (mod p)

I'm trying to create this gimmicky public-private RSA key pair where p and q are the same number. I would want to use the asn1 parser in OpenSSL, but I'm required to specify the coeff parameter, the ...
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RSA generating private and public keys

I'm trying to implement RSA encryption in PHP. I'm stuck at generating the public and private keys. I have P = 61, Q = 53, MOD = P * Q = 3233, N = (Q - 1) * (P - 1) = 3120. How do I chose the value ...
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How to calculate Public Key exponent if I have p, q, Dp, Dq, QInv? [migrated]

I have a private key components p, q, Dp, Dq, and QInv. I need to calculate the public key modulus and exponent. Modulus was super simple p*q, but exponent I can't figure out. Have searched all the ...
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Does this attack on RSA keys reveals a major flaw, or this is no big deal with good entropy?

William Kuszmaul published a study of an attack for RSA public keys on his blog https://algorithmsoup.wordpress.com/2019/01/15/breaking-an-unbreakable-code-part-1-the-hack/ The basic idea is, when ...
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Import GnuPG Subkey to other Primary Key

Let's say we have two gpg primary keys "Ident-A" and "Ident-B". There is also a subkey "Sub1" used for encryption by "Ident-A". It is possible to add a subkey "Sub2" to "Ident-B" using the private key ...
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Does the key size have an effect of the size of the public key and signature

If I have a 2048-bit RSA and a 4096-bit RSA key is my signature and public key smaller when I use a 2048-bit key vs a 4096-bit one ? (In bytes)
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RSA signature security with short keys

RSA keys with the size of 1024 aren’t considered to be safe anymore. Does this also apply if you use this key for signing only? Can a signature be faked easily with a short key length?
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ECDH and static key encryption

It's been a while and I'm still trying to figure out if my understanding of ECC crypto is correct. Basically from what I understood a purely asymmetric encryption is never used. Usually the ...
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Can I use RSA to encrypt an AES256 key that I put at the beginning of my AES256 encrypted file?

I have a master server generating large files for other (known) servers to download. Those files: Are quite big. From 20MB to 5GB. Are written once by the server and then it forgets about them. ...
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To what extent are countermeasures against side-channel attacks effective/ used regularly by everyone?

I'm doing an Extended Essay for IB right now and I'm doing it on how secure RSA is. As side-channel attacks are one category of attack, I was wondering (as I am struggling with the conclusion) while ...
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How does algorithms ensure public/private keys uniqueness? - RSA

I'm new to security and crpyto, I know that Public/Private keys are generated in a different way depending on the used algorithm, But let's take RSA as an instance (Using prime numbers), Does the ...
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Where To Store Public and Private Key files?

I'm creating a Java web-application using a WAR file to be deployed on a server. I will only be using one single web server and hosting. In my project, I'm generating two files: Public Key file and ...
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Does every recipient receive a different version of “encrypted” email using PGP?

If I understood it correctly, PGP encrypts email by using receiver's public key. In a multiple-receiver scenario, does that mean each receiver will get a different version of "encrypted" email but the ...
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Public Key Crypto - sign Bob's name into Alice's message or encrypt Alice's name

I was reading Defective Sign & Encrypt in S/MIME,  PKCS#7, MOSS, PEM, PGP, and XML and in section 5.1  Naming Repairs By signing Bob's name into her message, Alice explicitly identifies him ...
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Why digital signatures needs different algorithm

Why digital signatures uses algorithms such as DSA, ECDSA or RSA-PSS, and not just the RSA algorithm to encrypt the message hash with the private key? Is the choice more security or performance ...
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Naked RSA decryption

I'm working with some legacy code that uses naked RSA encryption with variable length packets. I've only found example code on how to handle this when the length of the packet is the correct length ...
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Is it necessary to encrypt messages client side if using HTTPS?

I am creating a messaging service for an app I'm developing and right now the data flow is as follows: Send: message sent to server => message encrypted based on user's public key and signed using ...
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SHA 1 with RSA for ssl certificate

Hi using SHA 1 with RSA encryption for ssl certificate is secure? As i know, sha 1 is not secure, but if we use RSA with sha1, still it will be an issue? Please suggest if any security issues exist.
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Does hashing a file consider its digital signature as well?

I have a signed (using Windows signtool) executable which is hashed by SHA1 algorithm and encrypted using RSA. Now I like to verify the executable to avoid security vulnerabilities. For that I have an ...
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Web Crypto API maturity for JavaScript RSA encryption?

We have been using a JavaScript crypto API to do RSA encryption in the browser. I know all the criticisms on encryption in JavaScript but we have evaluated pros and cons of the solution and the risks ...
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130 views

Recommended asymmetric algorithms for JWT?

I'm implementing JWT authentication for a new web service and am unsure which asymmetric algorithm to choose. I've searched around and haven't found any consensus or clear recommendations. According ...
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RSA uses substitution and shuffling?

I've been doing some searches for RSA and it appears that it uses shuffling but not substitution. Is this true? Simple explanation of the algorithm: https://www.geeksforgeeks.org/rsa-algorithm-...
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Deducing private key in RSA encryption from public key, cyphertext and plain text

Assuming someone is doing MITM attack. He knows the cyphertext, the public key and the plaintext message, can he deduce the private key from these 3 elements?
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How to handle end to end encryption [closed]

I am working on an app where the goal is to upload user data, store it, do some processing on that data and present it to user when asked. We want to follow end to end encryption model where the ...
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Storing RSA private/public key pairs in a file, on linux

Would it be wise to: Generate a lot of priv./pub. key pairs, and store them in a file on the server machine(Linux). (Let's say in a companies server room) Then encrypt the file with AES, and store ...
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mbedtls mutual authentication [closed]

I have a server CA cert, device cert and the device private key. I am using mbedtls and want to be able to create a mutual authentication connection between the device and the server. I also have to ...
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125 views

How to encrypt and sign a message with RSA?

I have been doing research on how RSA encryption works (mostly from a math's point of view) and I have come to understand this: By encrypting with the public key of bob, only bob can decrypt it with ...
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Does the symmetric key exchange through asymmetric encryption have to be done asymmetrically?

To communicate over a public channel, it seems often that 2 parties first use some asymmetric-encryption way to exchange a symmetric key. And then use the symmetric key for subsequent communication. ...
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How to enforce confidentiality while keeping the authenticity?

Below is an illustration of the digital signing process. According to Wikipedia: A digital signature is an authentication mechanism that enables the creator of the message to attach a code that ...
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Advantage Of ECDH-RSA over RSA Ciphersuites In TLS

If ECDH-RSA is used for key exchange, this is what happens: The server has its public ECDH parameter embedded within its certificate. The client generates its public ECDH parameter, extracts the ...
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when should i use HMAC-based JWT?

I read a number of blog posts and found that it is tough to keep the secret-key a secret and if using a symmetric algorithm for JWT creation, the generator has the power to create as well as validate ...
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How to authenticate using RSA avoiding MITM attacks

During my lessons of information security the professor told as that Alice can authenticate to Bob in the following way using RSA: Bob generates and sends a Nonce to Alice Alice signs this Nonce with ...
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Is RSA key-like browser authentication feasible?

I see that password based authentication is out of favor today, and Internet is moving toward RSA keys-based authentication. Coming from that fact, I am wondering if there would be a real benefit to ...
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446 views

Checking if an RSA private key is passphrase protected

I have generated an RSA key-pair on a computer, and I want to check if the RSA private key is encrypted (protected) with a passphrase. Note that the problem is not that I forgot the passphrase, but ...
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User specific AES-256 key for file. Retroactive encryption

I may be falling into a classic encryption-problem trap here... I've been developing applications using AES and public/private key encryption for some time so I have a good understanding of straight ...
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Compatibility advantages of RSA-4096 over RSA-3072

I am targeting a security level of 128 bits for GnuPG, so I am using SHA-256 and AES-128. Now I need to choose between RSA-3072 and RSA-4096. According to multiple sources RSA-3072 security level is ...
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193 views

Why is PKCS used? [closed]

Can anybody help me in understanding why PKCS is used? My confusion is that whether PKCS is used to transfer key in between client and server OR it is a standard to encrypt and decrypt the payload. I ...
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2answers
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Should the client or the server generate the client's public-private key pair?

Say I have a mobile messaging app. There is a central server that manages stuff (like a directory of users, onboarding, etc.) and there are all the clients. My app is professional, so it uses ...
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Is server public key and Diffie Hellman public are the same?

I am trying to understand the working of TLS. I understand that there are various way to generate the master secret used to encrypting the data. Such as DH (Ephemeral DHE) and RSA. I understand that, ...
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Why can a man-in-the-middle attack not happen with RSA?

I understand how RSA works (generate private/public key pair, send public key to whoever you want to talk to, encrypt with public, decrypt with private), but isn't there a flaw in this? Let's say A ...
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Does git use the ssh user keys or the repository's deploy keys for encryption?

In this question I asked, why the SSH-Host key shown when connecting to a gitlab repository does not match the one shown on the instance configuration page. Nevertheless, the accepted answer says that ...
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Is there a stream cipher equivalent when using RSA key pairs?

From what I can gather, when encrypting with RSA key pairs, you cannot encrypt more data than the length of the key (at least I can't find the implementation in the libraries I'm using). So then, in ...