Questions tagged [openssl]

OpenSSL is an open source implementation of the SSL and TLS protocols. Questions about how to use the OpenSSL tools and libraries are usually better asked at Stack Overflow or Super User.

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Differences between ssh-keygen private keys and libressl's? [migrated]

I generated a private key using libressl 3.0 using curve secp521r1. ...
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37 views

SDES algorithm purpose

What is the purpose of SDES algorithm? (Session Description Protocol Security Descriptions) What are the problems in the way it exchanges keys? I have tried to search about these quastions but i ...
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1answer
39 views

CSR signature using elliptic curve [closed]

We've been asked to generate a certificate signing request using elliptic curve and we can't use any third-party library as it's an embedded application with very limited resources). We are used to ...
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2answers
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Using RSA encryption with OpenSSL library: secure?

I'm working on a small program (in C) that writes encrypted log files, but there are a lot of articles out there that say you should avoid RSA whenever possible. However, most of these articles also ...
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1answer
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How does OPENSSL handle generation of unique IVs for AES-GCM

Generating unique IVs for AES GCM is elaborated in RFC-5288. However, I am unable to find an exact mapping of the explanation given in the RFC, with the OPENSSL C library. Could anyone help me with ...
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Does Openssl 1.1.1 library supports sending multiple identities as part of PSK?

Does Openssl 1.1.1 supports sending multiple ticket identities as part of PSK? i have gone through the openssl code and i don't see that openssl supports it. could someone please confirm it if i ...
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1answer
134 views

curve25519 by openSSL

How can i generate ec curve25519 keys using openSSL? When I run openssl ecparam -name curve25519 -genkey -noout -out private.ec.key I have this message ...
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1answer
42 views

How to use openssl securely? [closed]

I don't want openssl to log my keys and passwords... but I don't use gpg as I need more manual control for my purpose. I also don't like gpg and would like to use openssl without logging. Does ...
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1answer
57 views

Naming convention for NIST elliptic curves in OPENSSL

NIST standardized 5 elliptic curves (P-192, P-224, P-256, P-384, P-521) for prime fields. When I looked into openssl, these curves are named as prime192v1, secp224r1, prime256v1, secp384r1, secp521r1. ...
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1answer
64 views

Encrypt multiple RSA keys with same passphrase

I have to create and store a bunch of RSA key pairs with openssl. The private keys will be encrypted with the aes256 option and a very long, random password. Would it be safe to use the same password ...
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730 views

Why does OpenSSL differentiate between PSS and non-PSS for private key generation?

RSA-PSS private keys The following command will generate an RSA-PSS private key: ...
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1answer
154 views

Is the KDF pbkdf2 included in the openssl suite? [closed]

I'm trying to encrypt a file using DES in CBC mode but when I try to specify the key derivation function it tells me my command is wrong. It only fails when I try specify the KDF and works when I don'...
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Is openssl rand command cryptographically secure?

I'm wondering if the openssl rand command produces cryptographically secure random bytes. For example when in need for a random password or token: ...
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1answer
112 views

When do clients use TLS in PSK mode?

The TLS protocol can perform the handshake in different modes. Either fresh handshake where new keys are generated, or using Pre Shared Keys (PSK) or what was know as Session Resumption in previous ...
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1answer
286 views

Length of password requirement using openssl aes-256-cbc

I am using the following OpenSSL command to AES 256 encrypt a file: ...
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2answers
255 views

Using Diffie-Hellman secret key to encrypt/decrypt data?

My end goal is to encrypt data with AES-128, send it to other process and decrypt it there. While using DH key exchange protocol. I have used DH to generate a 256 bytes shared secret, but I can't use ...
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2answers
267 views

Why does Laravel only support AES-256-CBC?

Modern Laravel uses OpenSSL to provide AES-256-CBC encryption along with a MAC. However, I was under the impression that this is not a particularly secure approach. Why does Laravel only support AES-...
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1answer
90 views

How to determine the fastest OpenSSL cryptographic algorithm

This question does have to do with cryptography, but not necessarily with encrypting meaningful data. This is my first post here, so if I'm going about this question incorrectly please let me know. ...
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1answer
653 views

How does openssl signature verification work?

I would like to know how openssl verifies a digital signature? I know that it uses this command to verify a signature: ...
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1answer
192 views

Does RSASSAPSS use RSA signature

I just need to know is it correct to classify the RSASSAPSS scheme and sha[256 | 512 | 1]WithRSAEncryption all under RSA ...
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1answer
96 views

openSSL and ECDSA key format inspection

If I run openssl ec on a key that I have generated with openssl ecparam -genkey I get one extra prefixing 0x00 in the private ...
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1answer
418 views

SSL - encrypt with private key and then with public key?

Say there are 2 sides that wish to communicate: side A and side B. Let's say we are looking at side ...
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1answer
100 views

How to check a signed CSR with openssl?

I just learned that a CSR can be signed. See this Why is a CSR signed and which key is used for signing? I tried to check the csr with below openssl command, but failed with errors "139942025398160:...
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1answer
64 views

Unable to reproduce correct signature data

"Skatteetaten" is the Norwegian tax authority. We're currently trying to implement signing of messages for digital cash registry systems and i'm not able to reproduce the desired signed data. Went ...
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1answer
38 views

When a program using openssl library is using a certificate, does the server check if the issuer(s) are still valid

If I have a program acting as TLS server with a certificate signed by a CA, if one of the issuers in the chain becomes invalidated or the date expires, then how does the program using the certificate ...
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1answer
33 views

Are Authenticated Encryption ciphersuites supported in legacy TLS versions older than TLS 1.2?

I have read in a paper that Authenticated Encryption (by this I mean those that support GCM mode or ChaCha20 ciphers) are not supported in versions older than TLS 1.2? I could not confirm this as ...
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209 views

Simulation of Chosen Plaintext Attack on CBC, Predictable IV with OpenSSL

I would like to simulate the CBC IV attack where the IV is predictable. It's described in the answer to this question: chosen plaintext attack on CBC, predictable iv (Only "Yes" and "No" are valid ...
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2answers
708 views

The attacker model of the Lucky13 attack in TLS

Lucky13 is a timing attack against the MAC in the CBC MAC-then-encrypt ciphersuites. In the attack's page: The attacks involve detecting small differences in the time at which TLS error messages ...
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0answers
311 views

Encrypt multiple files with OpenSSL securely [closed]

I wish to encrypt potentially gigabytes of data on my pc, and I wish to be able to decrypt and use those files. However, I am a noob, so bear with me. My idea is to use ...
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1answer
477 views

Decrypting AES256-CBC with wrong encryption key

Using OpenSSL library is there any chance that decrypting AES256-CBC encrypted data with wrong encryption key will succeed without an error? Asking this because I have read somewhere there is 1/256 ...
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3answers
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What is different below two Ciphersuites?

I have two questions; I need an explanation for the differences of below two cipher suites. How do they work with SSL/TLS protocol? (my main concern first one doesn't have '...
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1answer
1k views

Why can't decrypt with OpenSSL if salt changed (for CBC and ECB)

A file encrypted with OpenSSL (with, for example, AES 256-bit mode CBC) using the Linux command openssl enc -aes-256-cbc -in texte -out encrypted_texte -k password ...
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1answer
336 views

What is the encoding protocol for passphrase protected RSA private keys?

What is the protocol used to encode an RSA key protected with a passphrase? If I generate an RSA key with ssh-keygen -t rsa -b 4096 and do: ...
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1answer
431 views

Is this a good PHP encryption Strategy?

I'm writing a multi-tenant application that interacts with a couple of different APIs on behalf of each customer. Obviously, we need to store private keys for these various different APIs in the ...
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1answer
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1answer
527 views

X25519 - why openssl shows 253 bits?

When using ECDHE with Curve25519 with openssl: Server Temp Key: X25519, 253 bits I thought when we use X25519, it use 256 bit key. Why openssl shows the server temp key as 253 bits?
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How to see Diffie Hellman private key used during negotiation? [closed]

I used OpenSSL s_client to connect to a test server. Because OpenSSL generated client side private DH key, I think there will be a way to show the private key or ...
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1answer
904 views

The “openssl genrsa” command only generates a private key?

The command : openssl genrsa -out RootCA.key 4096 generates a single file named RootCA.key. When I open the file, it only contains the private key. Then ...
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1answer
202 views

Question about OpenSSL testing for FIPS 186-4 and using BN_generate_prime_ex

I am working on testing my implementation of OpenSSL using the CAVP 186-4 RSA Validation System (RSA2VS). There are tools under openssl-fips-2.0.16/test and I am working on modifying fips_rsagtest.c ...
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1answer
86 views

Question about using BN_rand() [closed]

I am working on a project and I'm noticing a peculiar behavior that I was hoping someone could tell me if it is correct or not. I have a program that is trying to generate some random numbers using ...
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1answer
44 views

I am new to digital certificate 509V3 concept. can some one please clarify the below points [closed]

I am using RSA 2048 with SHA 256 primitive in certificate: How to verify the user certificate n + 1 with Root certificate n? why it is required to perform Certificate chain verification? How to ...
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1answer
54 views

Does the server signs message body after ssl handshake?

So after SSL handshake the master secret is used to securely transfer data encrypted using symmetric cryptography. My question is simple: after SSL handshake, when the server (for example my bank) ...
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1answer
268 views

What is the difference between: ecdsap, ecdsak, and ecdsab in the output of “openssl speed”? What do the letters P/K/B refer to?

openssl speed tests the speed of different protocols on your computer: ...
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Differences between DSA and RSA Algorithms

Despite having learned much related to RSA and DSA, I cannot understand their differences. Can anyone tell me at least 4-5 differences between these algorithms? I have just used them for two-factor ...
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1answer
248 views

Clarifications regarding ciphers and Nmap scan

I'm running the below Nmap command to test the strength of the cipher suites I have used in my host nmap -sV --script ssl-enum-ciphers -p 443 <host> The ...
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2answers
1k views

Appropriate key for AES 256 GCM

I am updating a system that has Rails' OpenSSL on one side and Python's cryptography.io on the other. The Rails side has to generate keys for the AES-256-GCM and here are two methods that appear to ...
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1answer
463 views

Do aes_256_gcm IVs just need to be unique for that key?

I'm using GCM (via openssl's EVP_EncryptInit_ex(ctx, EVP_aes_256_gcm(), NULL, NULL, NULL))). The IV's default length is 12 bytes. It says that the IV must be ...
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Benefits of using SSL certificate over a raw key pair for non-browser use?

For applications not involving CA signed certificates – or web browsers for that matter – it would seem to be easier to use a raw key pair if possible, rather than deal with potential formatting ...
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1answer
1k views

symmetric AES encryption with php produces different result than openssl MacOX

I need to make a simple very basic encryption with AES 128 ECB mode. The idea is to generate a cryptogram, code it in base64 and then decipher that text from a web service in php to process its ...
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openssl command line equivalent of AESWrap? (defined in RFC3394; use in AmazonS3 Client Side Encryption of datakey wrapping) [closed]

when dealing with S3 Client Side Encryption, it's using "AESWrap" (defined in rfc3394) algorithm to encrypt the data-key; I'm trying to play with openssl command line to see if it's possible decrypt ...