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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14
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1answer
6k views

What to watch for with openssl generating weak keys? (low entropy)

(Disclaimer: I am regular software engineer with only basic crypto knowledge, so helpful if can be explained for a layman.) I am concerned about generating weak keys on a shared linux box with ...
8
votes
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 ...
8
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3answers
3k views

How vulnerable is the C rand() in public cryptography protocols?

I just learned about the basics of public cryptography a few weeks ago and I am curious as to why the C rand() function should not be used for crypto schemes. For example, say I want to generate a ...
7
votes
2answers
685 views

Implement deniable encryption with AES/RSA

I'm on a crypto app using OpenSSL (I'm more an implementer/cryptographer than a cryptologist), mainly as a hobby, for now. My app will be able to encrypt a file (not a container) with symmetric or ...
6
votes
1answer
6k views

AES256-GCM - can someone explain how to use it securely (ruby)

I am looking into using AES256-GCM for encrypting some database fields. I know that for AES256-CBC, I need to generate a new IV for each encrypt, but I can use the same key. The IV can be openly ...
6
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2answers
467 views

Is encrypting credit card numbers one by one with rsautl secure?

I wish to encrypt credit card numbers one by one using asymmetric encryption on the command line. My current approach is this… Encrypt: ...
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 ...
6
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1answer
420 views

Difference RSA keypair creation openSSL and openPGP?

Creating a 2048bits RSA keypair I figured that doing this using openssl takes as an input 32bytes of "randomness" from ...
6
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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 ...
6
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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 ...
6
votes
1answer
473 views

ECC considered secure in OpenSSL?

If I perform the following command: openssl ecparam -list_curves using my OpenSSL version (1.0.1f), it spits out the following supported curves: ...
5
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2answers
1k views

Leaving authentication data blank less secure for AES GCM?

The AES GCM example for Ruby / OpenSSL shown at: http://ruby-doc.org/stdlib-2.0/libdoc/openssl/rdoc/OpenSSL/Cipher.html has a GCM example of the following: ...
5
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1answer
5k views

Why does OpenSSL append extra bytes when encrypting with aes-128-ecb?

Plaintext: Attack at dawn!! Hex: 41747461636b206174206461776e2121 Key: ...
5
votes
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 ...
5
votes
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?
5
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2answers
573 views

Which crypto libraries/programs do we have the most confidence in? [closed]

I have recently begun studying crypto. If it's one thing I have learned it's that we should not implement our own crypto. Therefore we should look to using existing software and libraries. When I ...
5
votes
1answer
79 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 <...
5
votes
1answer
2k views

Good entropy source for generating openssl keys

I need to generate a CA (4096-bit RSA) and server keys for openvpn and I want them to be "top quality". Here is my plan: gather entropy from multiple sources (saving individual files): FreeBSD ...
4
votes
1answer
8k views

How does TLS_FALLBACK_SCSV help?

After reading through https://tools.ietf.org/html/draft-ietf-tls-downgrade-scsv-0, I could understand that this option is recommened for use when one has legacy SSL Servers which only support SSLv3. ...
4
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2answers
672 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 $d$ ...
4
votes
1answer
169 views

How do I decide what mode to use?

I'll be using AES from OpenSSL. I understand why I don't want to use ECB from reading pages like this Wikipedia article, which has a great example of what happens when you attempt to encrypt with ...
4
votes
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 ?
4
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1answer
523 views

Blind signature with openssl

I'm trying to understand (to reproduce in practice) how does blinded tokens work. Currently i'm lacking examples. According to Wiki the blinded signature protocol is the same as ordinary signature ...
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 ...
3
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2answers
1k views

Openssl & RSA : how many public exponents are possible?

I would like to know if it is possible to set the public exponent we want with "OpenSSL RSA" or if it is really limited to 2 possible exponents: 3 65537 If yes, why ?
3
votes
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 ...
3
votes
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 ...
3
votes
1answer
191 views

Safety of AES ECB when used with openssl_seal function

I'm trying to use PHP to encrypt files with a public key. I'm using the function openssl_seal that "encrypts data by using RC4 with a randomly generated secret key." RC4 is considered unsafe so the ...
3
votes
1answer
105 views

Is this JS library using openssl genrsa -rand improperly?

pem, a JS wrapper around openssl, has the following code in it: var params = ['genrsa', '-rand', '/var/log/mail:/var/log/messages', keyBitsize ]; Am ...
3
votes
1answer
763 views

Why does openssl BN_generate_prime return only a fraction of the safe primes within the given bit range?

I went into prime generation issues the last week and eventually calculated 10^7 primes using erik tews safeprimegen python wrapper for openssl. (https://github.com/eriktews/gensafeprime) (System: ...
3
votes
1answer
1k views

Okay to use OpenSSL to encrypt then sign a message?

I am planning on encrypting a message then signing the message so the recipient can authenticate the source. Reading this article has me concerned that I'm doing something wrong. My current plan is ...
3
votes
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 ...
3
votes
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 ...
3
votes
1answer
124 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 ...
3
votes
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 ...
3
votes
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 ...
3
votes
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 ...
3
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0answers
1k views

Which eliptic curves in OpenSSL 1.0.1f meet all / most of the SafeCurves requirements? [closed]

I am using nginx compiled with OpenSSL 1.0.1f (most current release available). Nginx allows administrators to set a configuration parameter called ssl_ecdh_curve, ...
2
votes
3answers
475 views

In RSA, why does $p$ have to be bigger than $q$ where $n=p \times q$?

In openSSL – during RSA key generation – if $q$ is bigger than $p$, they exchange them. Why is that?
2
votes
3answers
7k views

OpenSSL AES 256-bit Key Management

I am using C and OpenSSL to encrypt files. After experimenting with the OpenSSL command line utility, it makes you enter a passphrase that can be any length, but uses that to create a 256-bit key. ...
2
votes
1answer
416 views

Is the DES algorithm in OPENSSL random?

Look at the hex dumps of encrypted1.bin and encrypted2.bin . They both have same password A which was used to encrypt sampletext ...
2
votes
2answers
3k views

OpenSSL PBKDF2 documentation

I'm using OpenSSL 0.9.8 on OSX Maverick, and I want to use a PBKDF but I can't find any doc/man about it on OpenSSL's website. I'm working on QCA, an OpenSSL wrapper for Qt, and when I arrived there ...
2
votes
1answer
690 views

RSA Decryption with Private Key but no public exponent

I manually set the RSA private key, given the private exponent and modulus. When I use this key to decrypt a message encrypted using a public key (also set with public exponent and modulus) seems to ...
2
votes
1answer
2k views

Sending TLS messages with out encryption using openssl code

Is it possible to send messages over TLS with out encryption? If so which cipher suite is needed for this?
2
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1answer
692 views

Why is 224 bit ecdsa faster than 192 bit ecdsa?

I ran several benchmarks using openssl on 2 different computers and I got a surprising result. for the Nist 192 bit curve the benchmark result is ...
2
votes
1answer
155 views

Pick faster private exponent

I recently tried to send 1536-bit modulus CSR to COMODO. They refused to sign the certificate. I later found out that it's because NIST mandated 2048-bit modulus on the SSL certificate. I think it's ...
2
votes
1answer
200 views

“Fine grain Cross-VM Attacks on Xen and VMware are possible” and OpenSSL 0.9.7

Here's a paper that just made its way into Cryptology ePrint Archive: Fine grain Cross-VM Attacks on Xen and VMware are possible!. Its a good survey of past attacks and presents a couple of new ...
2
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1answer
4k views

OpenSSL padding

I would like to know how much padding OpenSSL algorithms expect.
2
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1answer
390 views

random number generator and seed

I'm working with openssl cryptographic libraries, I'm new to all these cryptographic stuffs and slowly I'm learning all these. I have a doubt regarding random number generator, I'm using ...
2
votes
1answer
160 views

OpenSSL des-ede3 not producing same output as test vector implies it should be

I'm encrypting one of the standard TDEA/3DES/DES-EDE test vectors with openssl: ...