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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Is it possible to decrypt the 2nd byte of AES-256-CFB-8 ciphertext without decrypting the 1st byte?

I am stuck with AES-CFB decryption. Assume I encrypted plaintext helloworld (10 bytes) using AES-CFB. Now I want to decrypt the second byte ...
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1answer
153 views

Weird size of data transmitted in SSLv3

Note - I know SSLv3 is dangerous but that is why I am using it to do demo of POODLE attack using server and client written in python. So the question is I am using "ECDHE-RSA-AES128-SHA" cipher for ...
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1answer
2k views

Is openssl library safe threaded? [closed]

I'm encrypting in C++ with openssl library. Basically I'm using these functions: RAND_bytes(key, 32); AES_set_encrypt_key(...) AES_ctr128_encrypt(...) My purpose is to encrypt parallelly with ...
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2answers
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Complete Set of Test-Vectors for ECDSA secp256k1

Although there are several implementations of ECDSA secp256k1 public available over the internet (the most popular being OpenSSL), it seems that there are no complete set of test-vectors available. ...
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2answers
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What's wrong with RSA and OpenSSL?

We all know that signing a document is to encrypt its hash using signer's private key. https://commons.wikimedia.org/wiki/File:Digital_Signature_diagram.svg I've been searching the web for days, ...
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2answers
1k views

How Can I decrypt this VNC Authentication handshake?

I'm trying to analyze a mobile application and I believe it is is using DES. Here is a sample of the authentication handshake. ...
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1answer
3k views

How to generate sha 256 hash using https url

I want to generate sha256 hash of https url. ex: url "https://www.google.com/" I want sha hash of this url. I have tried extracting public key from ssl certificate and used following command. ...
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1answer
1k views

How is the PKCS #10 signature generated?

I'm generating certificate signing request in iOS, which does not provide proper ready-made API for CSR generation. Now the library I have used for CSR generation produces the different signature for ...
2
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1answer
256 views

Is there any use for PBKDF with empty password?

As the name suggests, password based key derivation functions are used for deriving a cryptographic key from, well, a password. Is there any use for PBKDFs with empty password? Does it give any ...
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1answer
868 views

How to create the right Blowfish padding? [closed]

I use the OpenSSL library for Blowfish encryption in ecb mode. The message are encrypted, but with the wrong padding, because of it I have a problems with decryption. What am I doing wrong? I checked ...
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1answer
1k views

'-in' is an invalid command. [closed]

While trying to convert private key into public key i get this error message. I used "openssl genrsa -des3 -out private.key 4096" to generate the private key and used "openssl -in private.key -...
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1answer
482 views

DES Weak Keys - Double Encryption

I know there are 4 known weak keys, their value and that double encryption using one of the weak keys should give back the plain text. I implemented this in OpenSSL. I have a plain text $m$ in a file ...
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2answers
127 views

Why don't parameters generated by dhparams conform to `(2^p) mod (p-1)/2 == 1`?

I've used openssl dhparams to generate 512-bit DH parameters for a test. The resulting file is: ...
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2answers
5k views

AES encryption without salt and IV

I need to encrypt blocks of 16KiB with AES256. I have only one requirement to satisfy - If one day a hacker gets the data without the keys, he will not be able to decipher the data. According to the ...
3
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1answer
11k views

Why is OpenSSL generated 256-bit AES key 64 characters in length?

This might be a noob question, but I couldn't find its answer anywhere online: why does an OpenSSL generated 256-bit AES key have 64 characters? The command I'm using to generate the key is: ...
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1answer
3k views

When a DER format RSA private key is extracted from an encrypted PEM file, is it still encrypted?

Let's pretend we create a passphrase protected PEM file using openssl: ...
3
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1answer
4k views

Extra attributes in a certificate signing request

When creating a certificate signing request, there is a part where openssl says "Please enter the following extra attributes to be sent with your certificate request". One of these is a challenge ...
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1answer
2k views

Nonce for AES GCM to prevent replay attacks

I am wanting to encrypt a message with a pre shared key that uses AES GCM from the OpenSSL library to do so. I generate my key for the AES crypto via hashing my pre shared key with a salt using the <...
2
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1answer
896 views

Why does 3DES need private key to decrypt?

I create two files, my.cer and my.pem ( include certificate and private key), I encrypt a file with my.cer, I use openssl smime -encrypt command. When decrypting data, it needs my.pem. I think 3DES ...
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2answers
8k views

What are KDF parameters in OpenSSL command-line utility for `enc`?

I refer to https://www.openssl.org/docs/manmaster/apps/enc.html and see that the only parameter for key derivation which I can set explicitly (not considering the obvious ...
2
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1answer
122 views

Insecure third party connection

My organization processes some PII data and shares it with an outbound connection (outflow only) that is a third party. The data transfer transactions occur without human intervention. That outbound ...
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2answers
8k views

Creating ECDH using OpenSSL

For academic reasons, I'm playing around with OpennSSL 1.0.2g. I tested RSA encryption/decryption. I created key exchange with DHKE. But I'm struggling to find a way, to create ECDH, using only ...
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1answer
517 views

Can TLS session resumption work after client dropped connection & reconnected to server?

I'm developing a sensor node and investigating TLS/OpenSSL. The network the node runs behind could drop and reconnect a lot. The node has limited data plan so data overhead is the key where TLS ...
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2answers
608 views

Is ssl_sign safe as it is using OPENSSL_PKCS1_PADDING

I've been hearing a lot of scare talk about PKCS1 padding attacks. Is PKCS1 v1.5 safe in signatures as it is practically transporting only message digest? I'm using it in one of my applications so i'...
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1answer
705 views

Does OpenSSL apply ASN1 encoding to the hash before signing using ECDSA?

I read on stack overflow that OpenSSL performs ASN1 encoding to the hash before signing it for, for ECDSA. In other words, OpenSSL performs the following steps when for an Elliptic curve key ...
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2answers
607 views

What may be causing conflicts in Whirlpool implementation versions?

I see by layman articles (e.g. at Wikipedia) that the Whirlpool hash function has seemingly three current versions. That is to say, they are referenced as ...
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2answers
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How does SSL work on the browser

I recently bought an SSL certificate from a website and was able to make it work on my Apache server. As far as I know, it uses asymmetric keys and the private key is stored on the server while the ...
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0answers
415 views

DES_cblock and Key Recovery [closed]

I'm trying to get my hands on the key that OpenSSL uses for a DES encryption. The key is based off a random number generator with a seed taken as parameter. The code used is below, provided as part ...
3
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1answer
3k views

Shouldn't a signature using ECDSA be exactly 96 bytes, not 102 or 103?

Attempting to use openssl to create a signature is confusing on several levels: If I'm using it to sign a hash that I've already created (HMAC-SHA-384-192, specifically), a. why must I specify ...
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1answer
26 views

What will browser show when a user access website and website present certificate of some other domain with same top level domain [closed]

For example, User tries to access a.example.com and server presents abc.example.com with a.example.com not in SANs list. Will it be just a warning or an error?
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2answers
605 views

Unclear about the importance of Initialization Vectors

I was reading about Ruby ciphers and found this: Although the key is generally a random value, too, it is a bad choice as an IV. There are elaborate ways how an attacker can take advantage of ...
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1answer
789 views

OpenSSL & TLS1.2 with aes-cbc and initialization vector

I'm trying to manually decrypt DTLS traffic using OpenSSL and TLS 1.2. The cipher suite im using is AES256-SHA256 as listed here. Im able to decrypt the packets with the key that the server and the ...
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2answers
4k views

OpenSSL Signature different each time

I have a file that I am generating a signature for using OpenSSL, and each time I generate the signature, it is different to the last time. ...
5
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1answer
164 views

How is SSL secure?

if the client and the server need to exchange keys and I can sniff it, wouldn't I be able to decrypt the data transported?
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1answer
848 views

How to correctly encrypt data with proper authentication using AES-256-CBC in php?

I have been using the openssl function for encrypting data with AES-256-CBC in php. I have been able to encrypt it using an unique IV (by generating with openssl_random_pseudo_bytes)for each new ...
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2answers
274 views

Recommendation for lightweight algorithm for partial message encryption

I have designed a specific client and server program, which sends a file from client to server in 32k chunks. I want to encrypt only part of the data. More specifically: in each 32k chunk passing ...
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2answers
235 views

Are low security curves for ECDSA not supported?

I am working in a very bandwidth restricted environment, and we are looking to implement ECDSA digital signatures. Although they are no longer recommended, we might be looking to use curves that are ...
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0answers
38 views

Are the ECDSA public keys of a stable/fixed length relative to curve size? [duplicate]

I am working in an environment with strict bandwidth requirements, and we need predictable bit lengths of the stuff we send. We need to broadcast ECDSA public keys, and we are using OpenSSL to ...
2
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1answer
1k views

Can I shorten the large ECDSA public key output file from OpenSSL?

I am working in a very bandwidth restricted environment where I from time to time have the need to distribute public keys. The distribution happens in bit format, so there is no need for encoding, at ...
3
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1answer
347 views

Is it secure to use hexadecimal data for IV instead of raw binary?

Is it safe and secure to use a function like bin2hex (which converts binary data to hexadecimal) on the binary output of functions like ...
2
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1answer
849 views

setting the MGF hash to a different value other than the regular hash with openssl for PSS signatures

In PKCS1's Probabilistic Signature Mode you have the Hash and the MGF Hash. Both appear to be, by default, sha1, with the OpenSSL CLI client, however, I can change it to sha256 with the following: <...
3
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1answer
5k views

Limit the length of AES encoded output to certain value

First let me be clear upfront that am not Crypto expert. I'm having a problem where I will have to use NFC card. Now given the limitation of NFC cards memory sizes, I will need to constraint my system ...
1
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1answer
135 views

How to store keypair generated by RSA in a textfile?

I'm trying to write an encryption decryption program using Openssl-RSA. There are only two operations. User stores the data and retrieves it whenever he needs. To decrypt something, we need the ...
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2answers
1k views

Different tools return different ciphertext value for equal input

I have a Luna G5 Safenet HSM and I want to encrypt a text file containing testtest with 3DES-ECB algorithm. So in the first step ...
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1answer
714 views

How to verify CA certificate from Yubico with openssl?

I'm going to verify the CA certificate from Yubico. I copied the whole certificate from -----BEGIN CERTIFICATE----- to ...
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0answers
300 views

How to check the signature without the predetermined function in ECDSA from openssl? [closed]

I'm developing a client for a two-factor authentication in Qt/C++ under openSUSE 13.2, 64bit. I've got the FIDO U2F Security Key from yubico/fido. I'm using the classes from openssl, in particular <...
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0answers
785 views

Why is SSL/TLS so complicated? [closed]

I'm new to SSL/TLS and I'm staring as a new security researcher. It appears to me that SSL/TLS protocol is needlessly complex for arriving at a shared secret. The complexity results in so many bugs (e....
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1answer
1k views

SSL implementation in windows? [closed]

SSL (Secure Socket Layer). windows Webbroswers ( Chrome, Mozilla, Edge, explorer ) are using which winapi set to Encrypt and Decrypt Data. SSL is asymmetric encryption. So which Api set is being used ...
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0answers
766 views

Fingerprint RSA public key in PKCS1 format [closed]

I can't find anywhere details on how to fingerprint a public RSA key in PKCS1 format. There are a lot of examples on the internet on how to fingerprint an RSA public key in openssh format using ...
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3answers
2k views

Can a billion elliptic curve keys be generated on a laptop in less than an hour?

I want my application to generate an EC key pair. The first four bytes of the sha256 hash of the public key should contain a known IP address. As hashes are one-way functions, I need to brute force ...