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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How does TLS differ from SSH from a strictly cryptographic perspective?

How does TLS differ from SSH from a strictly cryptographic perspective? I know that there are many non-cryptographic differences between them, but I would like to know the cryptographic ones.
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RSASSA-PSS in TLS 1.2

I know it is possible to use RSASSA-PKCS1-v1_5 with client certificates in TLS 1.3. But what about the other way around: using RSASSA-PSS with client certificates in TLS 1.2? Is it possible to use ...
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Can “OPAQUE-over-TLS” authentication be optimized?

So while discussing the issues of password-hashing off-loading in our chat I noticed that it's easy to extend OPAQUE (CFRG draft) to essentially be a better standard password based authentication when ...
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Implications of TLS-SRP client with improper N validation?

During development of a client side application of TLS-SRP, i noticed a bug that allows an attacker spoofing as the server to send custom, but non-arbitrary $N$ values, with the client accepting them. ...
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TLS handshake parallelization

As I understand, during TLS handshake phase, it is not legal for an endpoint to send its own handshake messages till the time it processes its peer's entire flight of messages completely. E.g. ...
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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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Why TLS finished handshake message contains hash of handshake messages

TLS handshake message FINISHED contains a PRF computation using master secret over hash of handshake messages exchanged so far. The application data records can flow only after the TLS endpoint has ...
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Timing Attack on OpenSSL by Brumley

I am referring to this paper by David Brumley and Dan Boneh: Remote Timing Attacks are Practical (In proceedings of the 12th Usenix Security Symposium, 2003). In this paper on page 4, Brumley ...
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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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Sharing RSA private key between SSH and SSL services. How bad is it?

An appliance uses a curious way of obtaining ssh-rsa host keys: There is a single configuration option "management certificate" that sets RSA private keys both for HTTPS and SSH management. ...
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Is my way safe to remove SSL CA Cert by DHT and PoW NodeID for a decentralized system?

To implement a decentralized system, I wrote a TLS like P2P net stack. The main idea is removing CA Cert from the whole system by using a DHT for Naming and Key Exchange. I am not a crypto expert, so ...
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What kind of RSA padding mode is it?

1: I have a HTTPS server and I added hooks in RSA decryption procedure to dump error RSA input(client key exchange). 2: I get some RSA input that I couldn't check padding successfully(It's usual) and ...
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Are there any one-way operations that could be used for Diffie-Hellman post-quantum? (See criteria)

With quantum-computers looming, there is a need for Public Key Cryptosystems that can withstand attacks by quantum-computers. Are there any known one-way operations that fit the following criteria? ...
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CRIME - attack TLS compression

In the CRIME attack slides at the Ekoparty presentation (where it was first introduced), I didn't get something. In slides 32-35 ( https://www.ekoparty.org/archive/2012/CRIME_ekoparty2012.pdf ) When ...
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TLS padding format

My question is about how the padding is formated in TLS1.0, 1.1, 1.2, 1.3 I came across the PKCS7 format for the padding: ...
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Test vectors for TLS PRF function

Does anyone know where I might be able to find test vectors for the PRF function in TLS? (either 1.0 or newer). I'm trying to implement a client and I am getting the BAD Record MAC return after ...
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Separate TLS Client Write and Server Write Keys in AES-CCM Mode

I am designing a system that uses TLS-like handshaking on a resource-constrained embedded system. I have settled on AES-CCM mode for symmetric session encryption and authentication, allowing ...
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Should layered use of crypto always have a cryptographic binding between the layers?

Reading the latest TLS weakness, it seems that multiple weaknesses have been found over the years caused by not ensuring that messages are sent over the same channel, and in general a lack of ...
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Is it possible to modify SSL handshakes to enable PFS while still using RSA during the handshake?

I know we could possibly be using DH key exchange, that would enable PFS. However, what if we make modifications on our SSL 3.0 handshake such that the only cipher we use is RSA for the achieving PFS? ...
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Could BREACH be used to determine an HTTPS URL?

I was reading this article and had a question.... http://arstechnica.com/security/2013/08/gone-in-30-seconds-new-attack-plucks-secrets-from-https-protected-pages/ As I understand it TLS/SSL work in ...
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How to increase Poly1305 performance?

I was analysing the Chacha20 algorithm and the Poly1305 MAC generation from RFC 7539. It seems that the Chacha20 is quite faster compared to AES on CPUs without hardware support like AES-NI. But ...
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Can Encrypt-then-MAC be used with session ticket resumption?

In TLS 1.2, say a session ticket is created for the current session (Session Tickets RFC 5077), and the current session uses the Encrypt-then-MAC extension RFC 7366 (I.E. both client and server ...
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Security of CCM using 8 byte MAC within TLS

In the Dutch "IT Security Guidelines for Transport Layer Security (TLS)" the ciphersuites using AES-128-CCM_8 (i.e. CCM with a 64 bit authentication tag) are considered "insufficient&...
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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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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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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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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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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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Which parts of a TLS connection can I safely reuse for DTLS to the same peer?

Suppose I need both encrypted TCP and UDP, say TCP for reliable control signals from server to client and UDP for low latency data from client to server. If I first establish TLS, for the DTLS ...
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Which 'info' and 'salt' parameters to use in HKDF for TLS 1.3?

all the following discussion is for HKDF in TLS1.3: Regarding the 'salt' parameter in - HKDF-Extract(salt, IKM) as written in RFC 5869: HKDF without having to protect the secrecy of the salt. In ...
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MAC with key supplied afterwards

Looking at HMAC and KMAC it seems that the key is always required up front, i.e. before starting to process any other data. However, in many protocols the key may not be known it advance. For instance,...
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Custom encryption scheme for SSL

Suppose that messages transmitted over SSL are modified as follows: the message is splitted in blocks, $B_1, ..., B_m$ (each with at most $2^{14}$ bytes) for each block $B_i$ we do: ...
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DTLS 1.2 Finished message

I am implementing DTLS 1.2 and using ECDHE_RSA_AES_128_GCM_SHA256 cipher suit. Below is my client finished message Can anyone explain this message? How many bytes for verify data? Is there ...
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Random numbers for Master Key and Key_block

Exploration through RFCs concludes that random numbers used in the creation of Master Key and Key Block(Key material for Encryption Key and Mac Secret) are from ServerHello.random and ClientHello....
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Is ChangeCipherSpec a part of handshake message in tls 1.2?

Is changecipherspec a part of handshake message in transport layer security (tls) 1.2 because according to rfc5246"ChangeCipherSpec messages, alerts, and any other record types are not handshake ...
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Key renewal when the sequence counter is only 32-bit

If we look at the use-case that our sequence counter within our TLS communication is only 32-bit, would an automatic key re-newal be necessary a lot more frequently? We're going to use state-of-the-...
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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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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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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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Understanding TLS certificate

I'm newbie in the word of TLS, and need some verification about my picture. I can use TLS with 3 or 2 participants: 3 participants: Client, server, CA (certification authority). The CA is where the ...
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What are the consequences of not checking the server mac in a TLS connection?

The context for this question (it's quite involved) can be found in this document: https://docs.google.com/file/d/0B15itpMWb2ztWTJrYTgzX204OVU However, I want to make it clear that you don't have to ...