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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How to decrypt a file using RSA and just a public.pem file?

I have an encoded file and a public.pem file. Is it possible to decode the file using the public.pem file or do I have to start looking at private keys? I tried https://github.com/Ganapati/RsaCtfTool ...
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1answer
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Issues generating keys/cyclic group for Cramer-Shoup Cryptosystem with OpenSSL

I'm trying to implement a Cramer Shoup cryptography system in C but I've run into problems with generating the keys. From what I have found on the wiki and in other papers, to generate keys for Cramer ...
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4answers
95 views

Does SSL connection provide integrity?

I'm new to cryptography and I'm trying to implement a secure chat application using OpenSSL. I want to ensure that public messages (which will be shown to all users) cannot be altered during ...
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28 views

How do I use XOF (SHAKE and cSHAKE) in openssl CLI and JavaScript

I am learning about hash functions and I just read about XOF (namely shake and cShake). I will like to test this functions out by myself but I can't seem to find how to use it via the OpenSSL CLI or ...
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1answer
94 views

OpenSSL EC PRIVATE KEY content structure details

Background I am trying to understand how PEM contents are formatted for "EC Private Key" so e.g. following is private key ...
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50 views

PKCS#7 digest encryption algorithm - difference between rsaEncryption and sha256WithRsaEncryption

As part of our linux secure boot implementation using dm-verity and root hash signature checking, I need to sign a file with the following openssl command (example): ...
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2answers
540 views

RSA Private Exponent Generation according to FIPS 186-4 in openssl v1

I guess this is more of a math problem in a cryptography context so I apologize beforehand if it is not the right place to ask. Basically I have to check whether a certain implementation of RSA key-...
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0answers
54 views

Coursera Course or book(s) That covers the following subjects: OPENSSL, SSH, PKI, MD5, RSA, Certificates, keys, signatures

I started working as a developper in a cryptography company 3 months ago where the applications are for mostly windows applications. I found that I don't have enough knowledge concerning the topics ...
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90 views

Generating certificate using ECDSA_P256 algorithm but with sha256RSA signature

If you have a look at a certificate encrypting google.com it advertises a 256-bit ECC key with ECDSA_P256 parameter. The signature algorithm is sha256RSA. I've been ...
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2answers
83 views

RSA short key generation using OpenSSL

To write a CTF challenge, I want to create an RSA key pair of size 228-bit. I want the keys exactly in the same format as OpenSSL-generated keys. But, OpenSSL is not supporting less than 512-bit long ...
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Checking Signature File is a Valid one

We are using a signature file which is in .pkcs7 format and has certificates encoded in it in DER format. In the process of verification of the signature we extract certificates and do final verify. ...
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0answers
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Can I store a public key used to verify a Schnorr signature in PEM format?

I want to ask if there is any way to store a Schnorr signature key in PEM format, or any other standardized format. And, if possible, I would like to know if that's possible to be done in C language; ...
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1answer
48 views

Extra bytes when decryping with OpenSSL

The string is encrypted with the following properties (using C#): myAes.Mode = CipherMode.CBC myAes.KeySize = 128 myAes.Padding = PaddingMode.PKCS7 myAes.BlockSize = 128 myAes.FeedbackSize = 128 Key: ...
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how does wireguard encrypted verifies with public key

After stumbling upon this question, I wondered if I could obtain a behaviour similar to WireGuard (private and public keys) by using the same WireGuard private key to encrypt a message via OpenSSL in ...
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271 views

Is OpenSSL enc using AES-256-CBC to encrypt large files safe?

I first generate a keyfile with openssl rand -hex 64 -out keyfile. I then encrypt the file with ...
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0answers
19 views

What is the difference between openssl functions - d2i_PublicKey & d2i_PUBKEY and what scenarios decide which should be used?

What is the difference between openssl functions - d2i_PublicKey & d2i_PUBKEY and what scenarios decide which should be used?...
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Decrypt web https-transmitted file manually [closed]

When the communication between server and client starts -after a request, the computers agree on an encryption protocol to protect the data, the TLS handshake. The data may not be encrypted on the ...
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0answers
56 views

How to decrypt raw TLS bytes?

Is there any tool / way to decrypt raw bytes of a TLS 1.2 session, when the master key is known, even if forward secrecy is used? The closest I found is this. I know its possible using Wireshark, but ...
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Openssl speed vs TLS speed with postquantum KEM

I'm studying the performance of postquantum KEM in TLS with the OQS (OQS is a project that integrate liboqs to openssl). I don't know why, but the KEM algorithms performance in TLS is 10 times slower ...
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0answers
67 views

How to encrypt a text file in a portable manner based solely on a password?

I used to use openssl aes-256-cbc, but the problem I have with this is when I try to decrypt in a different version of the distro it fails, as if it depends also on some internal key or something, ...
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1answer
179 views

AES Password Based Key Derivation Iterations

I have been writing my own implementation of the Advanced Encryption Standard with cipher block chaining in python3 for the last several months, mimicking the OpenSSL command line interface. I can ...
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152 views

OpenSSL DES encryption for KCV calculation

I'm trying to implement a simple command-line tool to calculate the (Key Check Value) KCV of some encryption keys. The algorithm for the KCV is simply to encrypt a block of 8 zeros with DES and get ...
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1answer
25 views

Do you need both client and server side support for TLS 1.3 record padding?

When you enable record padding for a client, does a server need a specific option to support this? Or does the other end only need to support TLS 1.3 as well and can handle the padding automatically?
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1answer
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OpenSSL TLSv1.3 record padding

OpenSSL supports TLSv1.3 record padding: https://www.openssl.org/docs/man1.1.1/man3/SSL_CONF_cmd.html but I'm not sure if it works like I think it does. If I would choose a factor of 2 it would make ...
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29 views

CMS encryption application using Windows system certificate store

Hy! I'm looking for an application, which can make cms encryption/decryption, but with the use of the windows certificate store. I already found out, that openssl can't do it out of the box (just by ...
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0answers
90 views

Constant time arithmetic implementation in DSA

I am trying to understand why it is a hard problem to have formally verified constant time arithmetic for DSA when compared with ECDSA. For instance, in ECDSA implementations of OpenSSL, we have ...
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0answers
69 views

How to look for implementations of universal hashing?

Being a physicist, I know very little about cryptography. In fact, the main two practical aspects I've learned so far are: Unless you're an expert, 1. Don't try to invent new cryptosystems and 2. Don'...
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1answer
62 views

Best suitable column type for openssl $tag,$iv,$key,$encrypted?

Which column type is best for storing $tag, $iv, $key, $encryptedData generated by openssl_encryption, and in which format I should save these values? I am using &...
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1answer
259 views

OpenSSL cipher suite support / key requirement for ecdhe_ecdsa_with_aes128_cbc_sha256

I hope this is the right place for that kind of question. So actually I am trying to test the TLS implementation of some industrial device. I have to write my own TLS implementation for this, for ...
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2answers
566 views

openSSL created CSR signature size of 73 bytes but should't it be 70 bytes

after creating CSR using openSSL with secp256r1 curve inspecting the file using openssl asn1parse -i -in ecTest.csr the size of ...
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1answer
499 views

OpenSSL supports AES, Camellia, ChaCha. How about Twofish, Threefish, Serpent?

If I understood correctly, some symmetric ciphers such as AES, Camellia, ChaCha are implemented in OpenSSL (along with several older ones) but some other commonly used and proven ciphers such as ...
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1answer
220 views

Why is an RSA public key BITWRAP-ed in ASN.1 DER encoding?

While playing around with creating an RSA public key, and decoding it using a home brew ASN.1 decoder, I ran into the fact that the public key is BITWRAP-ed. BITWRAP seems to be an OpenSSL modifier, ...
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1answer
573 views

OpenSSL aes-128-cfb does not produce expected size

I try to implement aes-128-cfb myself for learning. To confirm whether my implementation is correct, I want to verify it with a well-known library such as OpenSSL. But then I noticed something strange ...
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1answer
341 views

Do the session keys have the same value on both sides during TLS?

I have two questions about the sessions keys generated during the last steps of the Handshake phase: Do the "client write key" and the "server write key" have the same value, even ...
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69 views

Elliptic curve group inverse addition in OpenSSL

I am using group P-256 on OpenSSL with C++. My understanding was that, if you have a point $xP$ and then calculate (xP)^(-1) with EC_POINT_invert(group, xP_inv, ctx), then when I calculate: xP + (xP)^(...
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1answer
246 views

OpenSSL FIPS integrity check

As far as I know, FIPS requires a set of self tests (POST) to verify the cryptographic algorithms permitted and the integrity of the module. These tests are performed at run-time, so OpenSSL does a ...
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1answer
313 views

Can the EdDSA signature scheme be customized with OpenSSL?

EdDSA has currently two signature schemes: Ed25519 and Ed448. Ed25519 is the EdDSA signature scheme using SHA-512 (SHA-2) and Curve25519 Ed448 is the EdDSA signature scheme using SHAKE256 (SHA-3) ...
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0answers
106 views

Generate version 3 x509 certificate from version 1 CA

Please do forgive me for my naivety. I have inherited a legacy system wherein the CA which signs the certificate is of version 1. Is it possible to generate a x509 version 3 certificate which is ...
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1answer
75 views

What if the CSR is intercepted in transit while sending it to CA?

I was studying PKI the other day and I had a serious thinking about the following question. What is CSR? - It is a block of encoded text that is given to the CA when applying for an SSL certificate ...
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1answer
103 views

OpenSSL - What Data Is Used To Create A Certificate's Digital Signature?

I am coming up-to-speed on OpenSSL certificates. In all of my research I see where "data" is hashed to create a hash value that is used as the basis for a certificate's digital signature. This hash ...
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1answer
264 views

Would knowing the random seed help to break AES or similar?

Consider I knew the seed of the random number generator that Bob uses to send encrypted emails to Alice. Would I have an advantage in deciphering the message? Also, how does, for example, openssl ...
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2answers
499 views

OpenSSL - extract hash algorithm from signature data (PKCS#1 v 1.5)

PKCS#1 v 1.5 stores hash algorithm identifier that was used to digest the original message. I would like to know if and how to extract this information. I am working on a buffer containing the ...
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76 views

Diffie-Hellman + Asymetric encryption kept simple, or alternatives to TLS

I am working on a system that includes our dear friends Alice, Bob, and a server that is only partially trusted. I have spent the majority of the day reading up on various cryptography methods, but I ...
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1answer
84 views

What is the difference between DROWN and ROBOT vulnerability?

It seems like the main idea is the same for both the vulnerabilities then what is the difference?
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1answer
855 views

On what basis is padding chosen in OpenSSL?

I am using CAPI Engine in OpenSSL and I did some test. When I use TLS 1.0 or 1.1, during handshake and RSA signing, PKCS padding is chosen. When I use TLS 1.2, RSA signing uses PSS padding. What ...
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1answer
629 views

What is the difference between cfb and cfb1 and cfb8 ? ( like openssl's aria-128-cfb & aria-128-cfb1 & aria-128-cfb8 )

What is the difference between cfb and cfb1 and cfb8 ? like openssl's aria-128-cfb and aria-128-cfb1 and ...
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1answer
5k views

PKCS12 password of container and private key

As I understand pkcs12 defines a container structure that can hold both a certificate and one or more private keys. ...
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1answer
1k views

Is there a difference between password and key?

I encrypt data with this command: openssl aes-256-cbc -a -salt -in C:\Users\User\secrets.txt -out C:\Users\User\secrets.txt.encs The program then asks that I... ...
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1answer
420 views

OpenSSL not producing messages of expected size

I have a 16 byte file, and after encrypting it, its size weirdly changes. ...
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0answers
202 views

AES-GCM - what are "Payload Length" and "AAD Length"

For the AES-GCM mode within many cryptomodules, their FIPS-validation certificates list the options: Payload Length: 504, 512, 1016, 1024 AAD Length: 0, 504, 512, 1016, 1024 For example in OpenSSL, "...

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