Questions tagged [tls]

SSL (Secure Sockets Layer) and its successor TLS (Transport Layer Security) are protocols which provide communication security (privacy and integrity) for a bidirectional data channel.

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Prior art: SSH key authn over TLS?

I’m developing an application that runs over TLS. In addition to password-based authentication we’d like to be able to use SSH keys. Is there any prior art in using SSH keys for authentication over ...
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How to derive a private/public keypair from a random seed?

For RSA, my understanding is that large primes are found randomly to build a private/public keypair. If a static seed can be used in that random search process, it should be possible to derive the ...
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TLS 1.2 AES-GCM decryption problem

I'm trying to decrypt a PCAP encrypted with TLS 1.2. I have the private key and Wireshark is able to decrypt the data so what I am doing should work but there is obviously something wrong. The ...
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DTLS vs direct use of AES. What are the threats unique for direct use of AES instead of DTLS?

For regular traffic in mesh network (between Internet of Thing devices) customer decided to use one of two options: DTLS PSK ciphersuite - DTLS based on pre-shared symmetric key or direct use of AES -...
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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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Diffie-Hellman parameter for use in TLS derived from given finite-field group

I'm interested in cryptography, but unfortunately haven't found the time to dive into the topic much. I have done some quantum encryption stuff back in the day, but that isn't helping me with my ...
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Debug client certificate authentication on path with openssl

Website on https://example.com/login will request client certificate authentication. If it was directly on https://example.com then using ...
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66 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
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Chrome TLS 1.3 no TLS resumption with not secure connections

I am testing TLS 1.3 on a slower IoT device (120Mhz ARM). In my tests Chrome with TLS 1.3 will not allow TLS resumption (Session Tickets) when you have an not secure connection e.g. because of an user ...
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1answer
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How are initialization vectors used in TLS 1.1?

From my understanding, TLS 1.0 can use CBC to encrypt data. To do so, it creates one initialization vector (IV), and then uses the previous ciphertext block as the IV for the next record. I made this ...
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Why doesn't TLS provide E2EE?

Why doesn't TLS provide end-to-end encryption? This question is somewhat related to this, this and this. If you want to talk to someone, say, through facebook, the TLS connection ends in the ...
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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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Safe way to derive IV from the DH shared keys for AES-GCM?

I am preparing to use AES-GCM to make a secure communication program. Here is the procedure DH key exchange to get shared keys SHA256(shared keys) Use AES-GCM to encrypt a message while the key only ...
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Why is the server's public key always used in SSL encryption and never the client's public key?

I spent a lot of time looking for an answer to this question, but the majority of answers never explicitly explain why the client's public key is never used; it's always the server's public key that's ...
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1answer
80 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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Is HTTPS encryption using the RSA algorithm?

According to this article HTTPS and RSA is the same thing: https://tiptopsecurity.com/how-does-https-work-rsa-encryption-explained/ From other sources I learn that they are both asymmetric encryption ...
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Standards for finite-field discrete log cryptography

The NIST and TLS standards for Diffie-Hellman key exchange over a finite field all work in a subgroup of ${\mathbb Z}_p^*$ having prime order $q$, where $p = 2q+1$. On the other hand, DSA has a larger ...
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Comparison of end-to-end encryption and TLS

I am writing a comparison paper about security of electronic communication and I want to compare end-to-end encryption and TLS by giving two examples such as Whatsapp and Facebook Messenger. However, ...
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1answer
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Is there an actually an alternative to using Diffie Hellman in TLS handshake?

After looking into how TLS handshaking works it seems to inherently include the Diffie Hellman algorithm during the point where they generate a shared secret key. However as I look into this some ...
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Does the order of the “Finished” messages matter in SSL/TLS?

In SSL 3.0 and TLS versions 1.0 through 1.2 the last two messages are the "Client Finished" followed by "Server Finished" messages. These messages include an encrypted (under the established session ...
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Avoid Logjam TLS Attack?

As the Logjam attack allows a Man-in-the-Middle attacker to downgrade vulnerable TLS connections to 512-bit export-grade cryptography by modifying the ClientHello and ServerHello, can the Logjam ...
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1answer
198 views

Diffie-Hellman in Https: How are prime numbers picked?

I am trying to understand https, as I understand https uses the Diffie–Hellman method for keys exchange and then AES for encryption. But Diffie–Hellman needs two prime numbers, where do these come ...
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1answer
105 views

Why is there no “ephemeral non-DH EC” key exchange in TLS?

In RSA key exchange, the client picks a premaster secret and encrypts it with the RSA public key in the server certificate, and sends it to the server. This offers no forward secrecy. In ECDHE key ...
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1answer
126 views

Can a 3rd party decrypt static Diffie Hellman?

Do cipher suites that use static Diffie Hellman (not Ephemeral) allow for the same 3rd party decryption ability as RSA cipher suites? With RSA key exchange, 3rd parties can gain possession of the ...
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1answer
169 views

Double 3DES/TDES Encryption

If 3DES/TDES (officially TDEA or Triple DEA - Triple Data Encryption Algorithm) encryption is used twice, using 6 different keys K1-...
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What encryption to choose from the SSL library in python 3?

I've been researching some of the types of encryption that the python SSL library uses. Among them the best I've seen are: ECDHE-RSA-AES256-GCM-SHA384 TLSv1.2 Kx = ECDH Au = RSA Enc = AESGCM (256) ...
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Is it possible to multiplex TLS connections by SNI metadata without knowing any keys?

Imagine the following communication diagram: C1-----\ /--B1 C2------P---B2 ...----/ \--... We have multiple C(lients), call them C1, C2, etc. They connect to a ...
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TLS handshake with client later on acting as a server

Is it possible that a client which gets the Digital certificate of the Server during the TLS handshake then acts as a server? Because a server only needs to have a valid digital certificate which it ...
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TLS client authentication from static client image

I'm trying to implement mutual authentication for a TLS connection between a server (ONOS OpenFlow controller) and multiple clients (OpenFlow switches). I'm restricted in that I must create a single ...
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How is Pre Master Secret related to Client.random or Server.random if DH KEX is RSA

For TLS 1.2 cipher Suite AES256-GCM-SHA384, RSA is KEX(key exchagne algorithm). As per standards of RSA Diffie Hellman KEX, after 'ServerHello' message client gets server certificate and it generates ...
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Does SET in any way use SSL?

I just started a course in web security, and I was just wondering quickly if SET in any way would use SSL? I noticed it was developed in part by Netscape. But all I can find is comparisons between the ...
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174 views

TLS handshake cryptography AES key query

I am working on a IoT project where I am trying to perform manual handshake (SSL) for certificates and sending data to the server securely using HTTPS POST method. RSA is used for sending Pre-master ...
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RSASSA-PSS-SIGN modBits size

In RFC 8017 modBits is the length in bits of the RSA modulus n I am using 2048 RSA key ...
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Is encrypted e-mail sent over TLS 1.3 a form of “forward secrecy” (similar to something like Signal)?

One common complaint about GPG-encrypted e-mail is that it doesn't provide forward secrecy; however with opportunistic TLS becoming increasingly common in both IMAP and SMTP, it's not unreasonable to ...
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TLS 1.3 Security against PKCS#1v1.5

This paper explains an attack on TLS 1.3. This was published way back in 2015 when TLS RFC was in draft stage. My question is now TLS 1.3 RFC is finalized, is this attack got addressed?
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Observing cipher suites and certificate algorithms without man-in-the-middle

I manage a proxy server. Is it technically possible to observe and determine which cipher suite is selected between end points (client and server) without changing their SSL certificate, without ...
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Is it necessary to have a certificate when we use TLS

When we say a communication is secured by the latest version of TLS, can we say that Man-in-the-Middle attack is not possible? Do not consider the situations that we can down grade the communication ...
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Why do we need HMAC?

AFAIK, HMAC solves the collision problem of hash algorithms by mixing in a pre shared secret. Can't we just use the pre shared secret to symmetrically encrypt data and leave out the hashing?
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How does tls 1.3 cope with man in the middle (in key exchange)

in case i cannot do PSK (give the same key to both sides via physical means). i saw tls1.3 still support DH (doesnt matter that it is DHE or ECDH). isnt that makes it a weak key exchange? do they ...
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A simple misunderstanding of SSL/TLS

I just came to learn about Deffie Hellman Key Exchange. And a little bit about RSA. I came to DH from something about SSL. From what I understood before is that SSL uses DH and TLS uses RSA, but after ...
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Size of Key Material of TLS_DHE_RSA_WITH_AES_256_CBC_SHA

What is the size of key material required for generating MAC keys, encryption keys and IV when use TLS_DHE_RSA_WITH_AES_256_CBC_SHA ? How to calculate it?
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Is this pairing scheme for establishing trust between two devices with self-signed TLS certs secure from MITM?

Assume two devices (A and B) with self-signed TLS certificates (this part can't change). We want these devices to trust each other. One way to do this is to simply copy A's cert over to B's allowed ...
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Security of MAC-Then-Encrypt without MAC key authentication

We have the following settings in our system: TLS 1.2 using legacy cipher suite - OFB mode (using 64 bit block cipher) and trunkated CBC-MAC (32 bit). The goal is to achieve authenticated encryption ...
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1answer
156 views

TLS_DH_RSA_* cipher, how can static DH use an RSA certificate?

I am confused about TLS_DH_RSA_* ciphers because, for DH to work, the server certificate has to include a DH public key, but for server authentication the server certificate needs an RSA public key. ...
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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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Pitfalls of wildcard certificates with unique key pairs?

I am having difficulty finding information regarding using wildcard certificates with unique key pairs. I understand if you duplicate key pairs across multiple servers and one becomes compromised, an ...
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Talking TLS with EC cryptography and the secp256k1 curve [duplicate]

How reasonable would it be to speak TLS over the secp256k1 curve? My initial experiments show that OpenSSL supports it (albeit with special flags, see below): Running an OpenSSL client against an ...
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Why is it not possible to tap into the HTTPS traffic specifically going from the server to the client?

How I think HTTPS works when sending data from server to client: -Server has 1 public, 1 private key. -Client has access to the server's public key and not it's private key. -Client has no keys of ...
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How are public keys securely and reliably obtained across the internet?

I've just decided to start learning all about PKIs, and I have come across what seems like a paradox. When fetching a public key from either a server or a CA, how can we be sure that the public key ...
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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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