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TLS 1.2 vs TLS 1.3 Comparison
Understanding why TLS 1.3 is faster and more secure
Step 0 of 7
The big picture - TLS 1.2 vs 1.3
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The Big Picture
TLS 1.2 (2008)
Handshake:2 round trips
Cipher suites:300+ options (many weak)
Forward secrecy:Optional
0-RTT:Not supported
RSA key exchange:Allowed
Legacy algorithms:Supported (RC4, 3DES, MD5...)
TLS 1.3 (2018)
Handshake:1 round trip
Cipher suites:5 options (all strong)
Forward secrecy:MANDATORY
0-RTT:Supported (resumption)
RSA key exchange:REMOVED
Legacy algorithms:GONE (only modern crypto)
Key Insight:TLS 1.3 isn't just 'newer' - it's a fundamental redesign. Faster handshakes, mandatory security features, and no way to accidentally configure it wrong.
Handshake Comparison
TLS 1.2 Handshake - 2 Round Trips
Client
ClientHello
ServerHello, Cert, KeyExchange
--- Round Trip 1 ---
ClientKeyExch, Finished
ChangeCipherSpec, Finished
--- Round Trip 2 ---
Encrypted Data
Server
Total latency: ~100-300ms depending on distance
Loading a webpage (10 HTTPS resources):
TLS 1.22000ms
TLS 1.31200ms (-40%!)
TLS 1.3 + 0-RTT900ms (-55%!)
What Got Removed (Security Improvements)
| Removed | Why | Risk It Posed |
|---|---|---|
| RSA key exchange | No forward secrecy | Past traffic decryptable if key stolen |
| Static DH | No forward secrecy | Same problem as RSA |
| RC4 | Broken cipher | Multiple practical attacks |
| 3DES | 64-bit blocks | Sweet32 attack |
| MD5 | Broken hash | Collision attacks |
| SHA-1 | Weak hash | Collision attacks demonstrated |
| CBC mode ciphers | Complex, error-prone | BEAST, Lucky13, Padding oracles |
| Export ciphers | Intentionally weak | FREAK, Logjam attacks |
| Compression | Side channel | CRIME, BREACH attacks |
| Renegotiation | Complex, buggy | Multiple vulnerabilities |
What's left in TLS 1.3:
Key Exchange: ECDHE or DHE (forward secrecy required!)
Authentication: Certificates (RSA or ECDSA signatures)
Encryption: AES-GCM, AES-CCM, or ChaCha20-Poly1305
Hash: SHA-256 or SHA-384
That's it. No weak options exist.
Cipher Suite Comparison
TLS 1.2 - Too Many Choices (300+)
TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
Recommended
TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256
Fast, modern
TLS_RSA_WITH_AES_256_CBC_SHA256
No forward secrecy
TLS_DHE_RSA_WITH_AES_256_CBC_SHA
CBC mode
TLS_RSA_WITH_3DES_EDE_CBC_SHA
Weak cipher
TLS_RSA_WITH_RC4_128_SHA
Broken!
Problem: Easy to misconfigure. Weak ciphers still negotiated.
TLS 1.3 - Only 5 Options (All Secure!)
TLS_AES_256_GCM_SHA384
AES-256, strongest
TLS_AES_128_GCM_SHA256
AES-128, fast
TLS_CHACHA20_POLY1305_SHA256
Great for mobile
TLS_AES_128_CCM_SHA256
IoT/constrained
TLS_AES_128_CCM_8_SHA256
IoT, truncated tag
That's the complete list. Every option is secure.
Key Insight:In TLS 1.3, there's no 'cipher suite configuration' to mess up. All options are good. You literally cannot pick a weak cipher.
More Encryption, Sooner
TLS 1.2 - Certificate Sent in Clear
ClientHello🔓 Plaintext
ServerHello🔓 Plaintext
Certificate🔓 Plaintext ← Visible!
ServerKeyExchange🔓 Plaintext
ClientKeyExchange🔓 Plaintext
Finished🔒 Encrypted
Application Data🔒 Encrypted
Network observers can see which certificate (website) you're connecting to.
TLS 1.3 - Certificate Encrypted
ClientHello🔓 Plaintext
ServerHello🔓 Plaintext
EncryptedExtensions🔒 Encrypted
Certificate🔒 Encrypted ← Hidden!
CertificateVerify🔒 Encrypted
Finished🔒 Encrypted
Application Data🔒 Encrypted
Certificate is encrypted. More privacy.
Check & Configure TLS Versions
Check what a server supports
# Check TLS version with OpenSSL openssl s_client -connect example.com:443 -tls1_3 # Detailed check with nmap nmap --script ssl-enum-ciphers -p 443 example.com
Nginx - Enable TLS 1.3
ssl_protocols TLSv1.2 TLSv1.3; ssl_prefer_server_ciphers off;
Apache - Enable TLS 1.3
SSLProtocol all -SSLv3 -TLSv1 -TLSv1.1 # TLS 1.2 and 1.3 only
Should You Upgrade?
All modern browsers support TLS 1.3 (Chrome, Firefox, Safari, Edge)
All major cloud providers support TLS 1.3
OpenSSL 1.1.1+ supports TLS 1.3
Some old clients (IE, old Android) may need TLS 1.2 fallback
TLS 1.2 (2008) - 2 round trips
TLS 1.3 (2018) - 1 round trip
0-RTT - Zero latency resumption
Read the Complete TLS 1.2 vs 1.3 Guide
Deep dive into handshake differences, 0-RTT, removed features, and migration tips
