Analyzing TLS Handshake and Scan Summaries
The TLS Cipher Suite Checker parses and explains TLS connection details from text-based inputs. Developers, Site Reliability Engineers (SREs), and security reviewers can use this tool to identify negotiated protocols, cipher suites, and legacy algorithms without performing a live scan or connecting directly to a host.
The tool processes text from common TLS scanners, openssl s_client outputs, packet-analysis summaries, or short ClientHello and ServerHello notes. It recognizes common IANA names, OpenSSL aliases, and several common hexadecimal suite IDs. It does not decode raw binary data or packet capture files, and the input must be under 200,000 characters.
Protocol Versions and Parameter Roles
When analyzing TLS evidence, the tool identifies and displays the protocol versions present in the text. It categorizes identified protocol versions and cipher suites by their observed roles in the handshake:
- Negotiated: The specific protocol version or cipher suite selected for the active session.
- Offered: The protocol versions or cipher suites proposed by the client in the ClientHello.
- Observed: The parameters detected during the handshake monitoring.
If the analyzed text does not contain any recognizable protocol version, the tool displays the message: "No protocol version was found in the supplied text".
Cipher Suite Assessments and Findings
The tool evaluates identified cipher suites and assigns one of four assessments:
- Modern
- Review
- Deprecated
- Unknown
Based on the cryptographic algorithms present in the suite, the tool generates specific findings to highlight security risks and legacy configurations:
| Algorithm / Suite Type | Finding Displayed by the Tool |
|---|---|
| RC4 | RC4 is deprecated and must not be negotiated. |
| DES | DES is not secure for general TLS use. |
| 3DES | 3DES has a small block size and is deprecated for TLS. |
| NULL | NULL encryption does not provide confidentiality. |
| EXPORT | EXPORT suites intentionally use weak cryptography and are deprecated. |
| Anonymous | Anonymous suites do not authenticate the peer and are vulnerable to interception. |
| MD5 | MD5 is not secure for general TLS use. |
| SHA-1 | This suite uses SHA-1, which is deprecated for general TLS use. |
| CBC | CBC suites are legacy. Prefer an AEAD suite such as AES-GCM or ChaCha20-Poly1305. |
| Static RSA | Static RSA key exchange does not provide forward secrecy. |
| CCM-8 | CCM-8 uses a shorter authentication tag and needs a protocol-specific review. |
| Unknown Suite | This suite is not in the built-in common-suite map. Check the current IANA registry or scanner documentation. |
If no cipher suite is found in the input, the tool displays: "No cipher suite was found in the supplied text".
Key Exchange and Authentication in TLS 1.3
In TLS 1.3, the structure of cipher suites differs significantly from older protocol versions. For TLS 1.3 cipher suites, the tool displays the finding: "TLS 1.3 negotiates key exchange and authentication separately from the cipher suite."
In legacy versions (TLS 1.2 and earlier), a cipher suite name explicitly defines the key exchange mechanism (such as ECDHE or static RSA) and the authentication mechanism (such as RSA or ECDSA) alongside the bulk encryption algorithm and the hash function. In TLS 1.3, the cipher suite name only defines the symmetric cipher (the record encryption) and the HKDF handshake hash. The key exchange and authentication parameters are negotiated independently via extensions in the handshake, meaning they cannot be inferred from the cipher suite name alone.
Static Analysis Limitations vs. Live Scans
This tool performs static analysis on the text you provide. It is important to understand the limitations of this approach compared to a live network scan:
- No Host Connection: The tool does not connect to any host, verify certificates, measure key sizes, or test downgrade behavior.
- No Active Discovery: It cannot show every suite a server accepts; it only explains the specific parameters present in the provided text.
- No Binary Parsing: It does not decode raw packet bytes.
- Missing Fields: Any fields missing from the pasted text remain unknown.
Local Browser Processing and Privacy
Your pasted TLS details stay in your browser. The tool does not upload or save them.
Frequently Asked Questions
Which TLS output formats can I paste?
Paste text from common TLS scanners, openssl s_client, packet-analysis summaries, or a short ClientHello or ServerHello note. The checker recognizes common IANA names, OpenSSL aliases and several common hexadecimal suite IDs; it does not decode raw packet bytes.
Why does a TLS 1.3 cipher suite not show RSA or ECDHE?
TLS 1.3 cipher suite names describe record encryption and the handshake hash. Key exchange and authentication are negotiated separately, so they cannot be inferred from a suite name alone.
Does this result prove that a server is secure?
No. It explains only the text you paste. It does not connect to the host, verify the certificate, measure key sizes, test downgrade behavior or show every suite the server accepts.
What errors might I see when analyzing text?
If the input is empty, the tool displays: "Paste a TLS scan or handshake summary first." If the input exceeds 200,000 characters, it displays: "That summary is unusually large. Keep it under 200,000 characters." If no TLS version or cipher suite is recognized, it displays: "No TLS version or cipher suite was recognized. Paste readable scanner or handshake fields."