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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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 <...
3
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1answer
81 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
36 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 ...
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1answer
53 views

How efficient is OpenSSL? [closed]

It is apparent that OpenSSL is widely deployed and used, but how efficient is OpenSSL? What's some efficiency concerns of it? What kind of methods to they use to make OpenSSL efficient? Do they also ...
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2answers
147 views

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 ...
3
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1answer
64 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 ...
1
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1answer
67 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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2answers
673 views

Calculate the RSA private exponent from the CRT parameters

I am trying to make the RSA structure of Openssl manually, knowing the public key ($n$, $e$) and the CRT parameters $p$, $q$, $d_P$, $d_Q$, and $u = q^{-1} \mod p$. That is, I want to get the $d$ ...
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2answers
202 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 ...
0
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1answer
16 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
36 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
64 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
166 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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0answers
172 views

Implementing hmac+bcrypt in bash script

I was recently reading Mozilla's Secure Coding guidelines and found their password storage method interesting. They combine an hmac hash of the password with bcrypt which allows for added security ...
3
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0answers
38 views

DES_cblock and Key Recovery

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 ...
1
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1answer
77 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 ...
3
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1answer
114 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 ...
0
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1answer
19 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
32 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 ...
1
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1answer
42 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 ...
0
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2answers
45 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. ...
8
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2answers
7k views

With OpenSSL and ECDHE, how to show the actual curve being used?

Using openssl s_client -host myserver.net -port 443 I can see the cipher negotiated is indeed using ECDHE for session key ...
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0answers
79 views

Degrade in performance with SSL_OP_SINGLE_ECDH_USE?

We have used SSL_OP_SINGLE_ECDH_USE when setting up our SSL_CTX . This seems to be causing a degrade in performance. I'm not able to find proper documentation for it except that it generates new ...
5
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1answer
90 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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0answers
630 views

Using RSA key pair for file encryption

I'm looking for a way to perform encrypted nightly backups of a server I administer, without storing the decryption key on the server. A form of PK encryption seems ideal for this, as I can store the ...
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2answers
161 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 ...
3
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2answers
72 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 ...
2
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1answer
91 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 ...
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15 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 ...
3
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1answer
70 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 ...
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1answer
72 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
125 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 ...
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1answer
49 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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1answer
93 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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176 views

How to verify a signature with openssl methods from the ECDSA class?

I'm trying to verify my signature like I explained in my question before. But I have some problems to program my own verification without the verify methods of openssl. Therefore I'm going on to use ...
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56 views

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

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
84 views

Why is SSL/TLS so complicated?

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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2answers
706 views

Would it be better to split a file and then encrypt, or vice versa?

Assuming that you're paranoid before storing your file (distributed across a shared location), which will be the best case scenario: splitting the file first and then encrypting or encrypting first ...
1
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1answer
77 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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102 views

Fingerprint RSA public key in PKCS1 format

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 ...
3
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1answer
105 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 ...
0
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0answers
72 views

MD5 SSL Collision Attack

I want to create fake certificate for test purposes. I have read about the http://marc-stevens.nl/p/hashclash/index.php project but I am unable to understand the two files that I have to put as input ...
6
votes
1answer
108 views

How to exctract ECDH parameters from an OpenSSL-generated $G$?

I'm using ECDH for generating ECDH public parameters (p,a,b,G,n), I try to get this values using openssl ecparam -in cert.pem -text -noout For ...
0
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1answer
1k views

generate RSA public key having public modulus and exponent [closed]

i want to generate an RSA public public key file using openssl (or other tools) having public modulus and exponent, so i can use it later to encrypt files i have this: ...
4
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1answer
200 views

Why a key pair is used in OpenSSL ECDSA_sign or ECDSA_do_sign instead of only private key ?

If the digital signature in ECC (ECDSA) is made using a private key, why is the OpenSSL library using ECKEY pair as an input parameter instead of the private key only ?
6
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1answer
227 views

How is OID 2a 86 48 86 f7 0d parsed as 1.2.840.113549?

I saw that an RSA key, created by OpenSSL, contains the following HEX string: 2a 86 48 86 f7 0d 01 01 01 that HEX string gets interpreted as Object ID: 1.2.840.113549.1.1.1 It is obvious ...
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734 views

Decrypt using OpenSSL produces packing errors

I am receiving an encrypted file and it's key from a partner. The Key has itself been encrypted using our Digital Certificate Public Key, though I don't know exactly how. The partner has instructed me ...
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2answers
315 views

How to derive a symmetric key from ECDH shared secret?

I am trying to implement the internal primitives of ECDH. Currently I'm able to multiply the receiver's public EC point with the sender's private key to arrive at the shared EC point. Next step is to ...
3
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1answer
103 views

Size of encrypted AES CEK in CMS block

When I run openssl cms -encrypt -aes256 -in sample.der -out wrapped.der -outform DER -recip ecc.crt -keyopt ecdh_kdf_md:sha512 the part of the CMS output which ...