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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1answer
94 views

Why don't the TLS1.3 cipher suites mention the key exchange and digital signature algorithm in names?

Does it mean both RSA and ECDSA certificates can be used with the same cipher suite?
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1answer
39 views

When a program using openssl library is using a certificate, does the server check if the issuer(s) are still valid

If I have a program acting as TLS server with a certificate signed by a CA, if one of the issuers in the chain becomes invalidated or the date expires, then how does the program using the certificate ...
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0answers
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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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1answer
229 views

In a TLS 1.3 connection, how do the client and server choose a mutual cipher suite?

According to KeyCDN, TLSv1.3 connections are established in a single round trip: While TLS 1.2 requires two round-trips to complete the TLS handshake, 1.3 gets the job done in just one trip If ...
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2answers
2k views

Why did TLS 1.3 prohibit PGP authentication?

There is a specification, in Informational(!) RFC 6091, for using PGP keys in TLS authentication, although I don’t think it has ever been implemented outside of GnuTLS (it’s certainly not in OpenSSL). ...
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1answer
37 views

Are Authenticated Encryption ciphersuites supported in legacy TLS versions older than TLS 1.2?

I have read in a paper that Authenticated Encryption (by this I mean those that support GCM mode or ChaCha20 ciphers) are not supported in versions older than TLS 1.2? I could not confirm this as ...
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2answers
2k views

Why does curl need both root and intermediate certificates in order to securely connect to an HTTP server?

I have created a root certificate, an intermediate certificate, and a server certificate: ...
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1answer
701 views

Why does TLS 1.3 support two CCM variants?

One of the important improvements introduced in TLS 1.3 is the pruning of the many previously available cipher suites to only five secure options (for symmetric ciphers), that are each supposed to ...
7
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1answer
346 views

Cipher suites: same name, different IDs, why?

Sorry if I missed with a community to ask. Recently I stumbled on a fact that the same cipher suite can be designated by two different IDs, and this is not a typo nor single occasion. For instance: ...
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2answers
811 views

The attacker model of the Lucky13 attack in TLS

Lucky13 is a timing attack against the MAC in the CBC MAC-then-encrypt ciphersuites. In the attack's page: The attacks involve detecting small differences in the time at which TLS error messages ...
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4answers
82 views

TLS ciphersuite without mode of operation

Will there be any security concern if there is no mode of operation specified in the ciphersuite name? For instance, there is no mode of operation in ...
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4answers
673 views

JWT Login Security

I am new to security and I am wondering if JWT is secure enough. From what I have read online the flow goes like this: Clients log in by sending their credentials to the identity provider. The ...
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1answer
867 views

CBC related TLS cipher suites to be disabled in the server side

I understand the TLS cipher suites using CBC mode are susceptible to timing attacks. From that understanding it seems that the cipher suites using GCM (CTR-based) are safe to use considering they don'...
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2answers
195 views

Does the Server Key Exchange sign a hash or text

In TLS 1.2 when using ECDHE_RSA, the ServerKeyExchange message contains a signature over the server's ECDHE public parameters. My question is: Is the signature over ...
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1answer
198 views

How Elliptic-Curve affects the Server Key Exchange parameters

In Finite Field DHE, the server sends the following parameters in the server key exchange message: $p$: prime $g$: group $g^b$: the server's public DH key In DHE_RSA (non anonymous DHE), the server ...
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1answer
62 views

When using Client Certificates, is it usual to generate your own?

We're building a webservice for a third party customer who wants us to use "two-way SSL". By which I understand them to mean they want us to host the site using https, and to require that include a ...
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3answers
2k views

What is different below two Ciphersuites?

I have two questions; I need an explanation for the differences of below two cipher suites. How do they work with SSL/TLS protocol? (my main concern first one doesn't have '...
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2answers
526 views

signature with Bleichenbacher’s attack

I understood Bleichenbacher & ROBOTO attack, however I have some trouble understanding Section 3.5 of ROBOT attack which discusses retrieving private keys. https://www.usenix.org/system/files/...
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1answer
380 views

Cipher Block Chaining (CBC) encryption in SSL

Is cipher block chaining (CBC) mode used in SSL encryption? If block reordering is already protected by SSL and TCP sequence numbers, what added advantage does CBC provide?
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1answer
189 views

How is the TLS 1.2 sequence number generated?

In the other ciphers supported by TLS 1.2, namely stream cipher and CBC block cipher mode, the sequence number is implicitly in the MAC (RFC5246, 6.2.3.1): ...
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1answer
381 views

Tls protocols: is the simple diffie hellman key exchange still used these days?

Or did it mostly get replaced by ecdh for key exchange and rsa for authentication ?
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1answer
81 views

Does DROWN attack break 2048-bit key itself or just the plaintext encrypted with the RSA key

Does the DROWN attack enable breaking strong RSA keys (e.g. the 2048-bit key itself) or enable breaking the plaintext (i.e. pre-master key) that is encrypted with a 2048-bit (or any strong) RSA, if ...
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0answers
47 views

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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1answer
387 views

How does OpenVPN work?

I'm confused with the technologies that OpenVPN uses. The official site mentions it uses SSL/TLS in-place of IKEv1/IKEv2, and uses IPSec ESP to secure the data, and yet that it isn't compatible with ...
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1answer
96 views
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1answer
55 views

How to prove to a third-party that a given response came from a specific domain?

Suppose I've got a response from a website using https. Is it possible to store the certificate and keys exchange to prove to a third-party that the response came from that domain?
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1answer
193 views

Can the lengths of HTTPS requests be used to deduce which public pages on a site are visited?

I thought of this recently: There are some websites which have many publicly accessible pages, some of which could be embarrassing despite being public (e.g. Wikipedia). The HTML for these pages also ...
2
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1answer
469 views

In TLS 1.3 handshake, what's “PSK binders” used for?

PSK handhanke works like session ticket resumption in TLS 1.2, but I found a set of PSK binder for each identity(ticket) in TLS 1.3, why ...
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1answer
82 views

What's the `ticket_age_add` and `obfuscated_ticket_age ` used for in TLS 1.3

In RFC, I only find such description: This addition prevents passive observers from correlating connections unless tickets are reused ...
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1answer
889 views

What is the most popular cipher suite used in TLS 1.2 for HTTPS?

I'm trying to do some performance (time) calculations over TLS. I have the data I need for a variety of cipher suites but in order for the calculations to generalize well, I need to know if there is a ...
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2answers
189 views

UDP and AES with C++

I'm implementing different applications that will use UDP to exchange real-time data, thus a low impact on performance is very important. This system will not be connected to the Internet so I just ...
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2answers
101 views

Private key ECDSA/TLS

Is the private key required once the certificate is hashed and signed? After a certificate is generated, public key is shared within the certificate itself. Is the private key used for any other ...
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2answers
18k views

Why doesn't SSH use TLS?

Most cryptographically protected protocols use TLS these days. This applies to mail protocols, HTTP and many others. The newly designed QUIC has also adopted TLS as its cryptography layer. However, ...
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1answer
57 views

Does the server signs message body after ssl handshake?

So after SSL handshake the master secret is used to securely transfer data encrypted using symmetric cryptography. My question is simple: after SSL handshake, when the server (for example my bank) ...
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2answers
74 views

How does authentication work differently between asymmetric and symmetric cryptography?

Must Bob and Alice establish a 'connection' before a symmetric or asymmetric encryption scheme is secure? If so, is there ever some expected plaintext whose decryption authenticates the users? In ...
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2answers
234 views

TLS1.2 AES 128 CBC Encrypted Data size is not a multiple of block size [closed]

I know that TLS ciphers such as TLS_RSA_WITH_AES_128_CBC_SHA transmit data as shown https://tools.ietf.org/html/rfc5246#section-6.2.3.2. From my understanding the ciphertext MUST be a multiple of the ...
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1answer
219 views

TLS Extension signature_algorithms values

I hate asking for a reference, but I'm having a hard time finding this. The iana page on tls extensions just links me back to rfc5246 where it only has the following values: ...
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1answer
3k views

HMAC Key Sizes for MD5, SHA1, SHA224|256|384|512

I'm trying to find an authoritative source for the HMAC Key sizes for each of the hashing algorithms below. Specifically for TLS implementations of HMAC. I found this table in RFC5246: ...
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1answer
313 views

does TLS 1.3 use ECDSA-Sig-Value encoded signatures for Ed25519 / Ed448?

Quoting The Transport Layer Security (TLS) Protocol Version 1.3: ECDSA algorithms Indicates a signature algorithm using ECDSA [ECDSA], the corresponding curve as defined in ANSI X9.62 [...
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1answer
2k views

TLS 1.2 Cipher Suites With AES-GCM – What data (if any) is passed to the AES-GCM cipher as the Additional Authentication Data?

TLS 1.2 defines a number of cipher suites that employ AES-GCM, e.g.: ...
4
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1answer
472 views

TLS: Risks of using a NULL cipher with encryption implemented in application?

We have a browser-launched JNLP/WebStart application that is no longer able to establish client-server CORBA/IIOP communications across TLS 1.0/1.1 due to relying on a cipher suite that uses an ...
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1answer
125 views

Advantages of a TLS handshake over pre-shared public keys

Lets assume the following setup: A vendor manufactures IoT devices where each is able to generate an individual private/public key-pair. Only the public key is exposed, the private key is assumed to ...
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2answers
2k views

Are TLS 1.2 AES-CBC and AES-GCM Authenticated Encryption ciphersuites?

In the answer of the following post: Why was AES CBC removed in TLS 1.3?, I quote the following from the chosen answer: After the Lucky13 attack (a timing oracle caused by MAC-then-encrypt), it ...
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2answers
310 views

What is a size of mac_length and mac_key_length for TLS cipher suites HMAC using SHA384 and SHA512?

i failed to find explicit definition of hash output size and mac_key_size for hmac based on SHA384 and SHA512. RFC5246 specifies: but defines only
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2answers
86 views

Self signed certificate for mobile app and backend from same company

My company's product is Android and iOS mobile app which connects to our own backend. All interactions of the mobile app are with backend developed by our own company. In such a situation, can the ...
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1answer
301 views

Clarifications regarding ciphers and Nmap scan

I'm running the below Nmap command to test the strength of the cipher suites I have used in my host nmap -sV --script ssl-enum-ciphers -p 443 <host> The ...
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2answers
3k views

What's the difference between rsa_pss_pss_* and rsa_pss_rsae_* schemes?

I'm trying to understand the difference between rsa_pss_pss_ and rsa_pss_rsae_. The picture shows the extension of TLS1.3's ...
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1answer
85 views

Does semi-honest adversary eavesdrop honest parties communication?

Assume we have a multi-party computation protocol and the protocol definition, where both of them consider a semi-honest adversary, without explicitly assuming the type of channel the parties want to ...
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1answer
719 views

TLS 1.3: HKDF-Expand

In RFC5869 I found that the function of the HKDF-Expand on the input assumes the parameter $L$ which denotes length of output keying material in octets ($\leq 255*\text{Hash}_{Length}$), and then the $...
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0answers
160 views

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 ...