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TLS Cipher Suite Parser

Networking
Enter a name like TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 or a hex code like 0xC02F

Quick Examples

About This Tool

TLS Cipher Suite Parser – Decode Encryption Algorithm Names

Every TLS connection is secured by a cipher suite — a structured name that encodes exactly which cryptographic algorithms are in use. A name like TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 tells you the key exchange method, the authentication mechanism, the bulk encryption algorithm, and the MAC or pseudo-random function, all in one string. The TLS Cipher Suite Parser decodes any IANA-registered suite name or four-digit hex code into its individual components, adds a security rating, and highlights any known weaknesses.

Anatomy of a TLS Cipher Suite Name

TLS 1.2 and earlier suites follow a predictable convention defined by IANA. The name always begins with the protocol prefix (TLS_ or SSL_), then describes the algorithms separated by underscores:

  • Key Exchange — how the symmetric session key is established. Common values are ECDHE (Elliptic-Curve Diffie-Hellman Ephemeral), DHE (Diffie-Hellman Ephemeral), and RSA (direct RSA encryption of the pre-master secret).
  • Authentication — how the server proves its identity, typically via its certificate. Common values include RSA, ECDSA, and DSS.
  • Bulk Encryption — the symmetric cipher used to encrypt payload data, separated from the prefix by the keyword WITH. Examples: AES_128_GCM, AES_256_GCM, CHACHA20_POLY1305, AES_128_CBC.
  • MAC / PRF — the message authentication code or pseudo-random function. For AEAD ciphers like GCM, this doubles as the handshake hash. Examples: SHA256, SHA384.

TLS 1.3 Cipher Suites

TLS 1.3 simplified the naming convention significantly. Suites like TLS_AES_128_GCM_SHA256 contain only the AEAD encryption algorithm and the hash function — there is no key exchange or authentication in the name because these are now negotiated separately through extensions (key_share and signature_algorithms). All TLS 1.3 suites mandatorily provide Perfect Forward Secrecy and use authenticated encryption, making them the preferred choice for modern deployments.

Forward Secrecy and Why It Matters

Perfect Forward Secrecy (PFS) means that even if an attacker records encrypted traffic today and later obtains the server's private key, they cannot decrypt those past sessions. PFS is provided by ephemeral key exchange algorithms — ECDHE and DHE — which generate a fresh key pair for every session. By contrast, the older RSA key exchange (where the client encrypts the pre-master secret directly with the server's long-term RSA public key) provides no forward secrecy.

How to Use the Parser

Paste a full cipher suite name such as TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384, or enter a four-digit IANA hex code like 0xC02C (with or without the 0x prefix). The tool normalises the input, resolves hex codes to their canonical names using the built-in IANA registry, and displays each decoded component alongside a security rating and advisory notes.

Security Ratings Explained

The tool assigns one of four ratings based on the algorithms present:

  • Recommended — ECDHE or DHE key exchange with AEAD encryption (GCM, CCM, ChaCha20-Poly1305) and a SHA-256 or stronger hash. Safe for all modern deployments.
  • Acceptable — Meets modern standards but may not qualify for the highest compliance tiers. Review your security policy before using.
  • Weak — Contains at least one algorithm with known limitations: RSA key exchange (no PFS), 3DES (SWEET32 birthday attack), CBC mode with SHA-1 (BEAST, Lucky 13), or SHA-1 MAC. Disable these if possible.
  • Insecure — Contains a broken algorithm: RC4 (statistical biases), MD5 (collision attacks), NULL encryption, DES, or export-grade ciphers (FREAK, LogJam). Never use these on production systems.

Common Use Cases

The TLS Cipher Suite Parser is useful for security engineers auditing a server's TLS configuration, developers integrating TLS settings into their applications, students learning about cryptographic protocols, and network administrators reviewing packet captures or TLS handshake logs. You can cross-check the cipher suite negotiated by a TLS handshake — visible in tools like Wireshark or openssl s_client — against current best practices without memorising the IANA registry.

Limitations

The built-in hex code registry covers the most widely deployed cipher suites; obscure or vendor-specific hex codes may not resolve. In those cases, enter the full suite name directly. The security rating reflects general cryptographic best practices and does not constitute a formal compliance assessment under standards like PCI-DSS or NIST SP 800-52. Always consult your organisation's security policy and the latest IANA TLS Cipher Suites registry for authoritative guidance.

Frequently Asked Questions

Is the TLS Cipher Suite Parser free?

Yes, TLS Cipher Suite Parser is totally free :)

Can I use the TLS Cipher Suite Parser offline?

Yes, you can install the webapp as PWA.

Is it safe to use TLS Cipher Suite Parser?

Yes, any data related to TLS Cipher Suite Parser only stored in your browser (if storage required). You can simply clear browser cache to clear all the stored data. We do not store any data on server.

How does the TLS Cipher Suite Parser work?

Enter a TLS cipher suite name (e.g. TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) or a 4-digit IANA hex code (e.g. 0xC02F). The tool splits the name at the _WITH_ delimiter and decodes each segment: the prefix yields the key exchange and authentication algorithms, and the suffix yields the bulk encryption algorithm and MAC or PRF. For TLS 1.3 suites there is no key exchange in the name; the tool notes that these are negotiated via extensions.

What is the difference between key exchange and authentication?

Key exchange (e.g. ECDHE, DHE, RSA) determines how the session key is established between client and server. Authentication (e.g. RSA, ECDSA, DSS) determines how the server (and optionally the client) proves its identity using a certificate. In many suites these are distinct — for example, ECDHE_RSA means ephemeral ECDH is used for key exchange while the RSA certificate authenticates the server.

What does forward secrecy mean and why does it matter?

Forward secrecy (also called Perfect Forward Secrecy, PFS) ensures that compromising a server's long-term private key cannot be used to decrypt previously recorded sessions. It is provided by ephemeral key exchange algorithms — ECDHE and DHE — where a fresh key pair is generated for every session. RSA key exchange does not provide forward secrecy.

Which cipher suites are recommended for modern TLS?

For TLS 1.3, all three mandatory suites are secure: TLS_AES_128_GCM_SHA256, TLS_AES_256_GCM_SHA384, and TLS_CHACHA20_POLY1305_SHA256. For TLS 1.2, prefer ECDHE suites with AES-GCM or ChaCha20-Poly1305 (e.g. TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256). Avoid suites using RC4, NULL encryption, MD5 or SHA-1 MACs, DES, or 3DES.

Why are some cipher suites marked insecure or weak?

A suite is insecure if any algorithm in it is cryptographically broken: RC4 has statistical biases exploited in real-world attacks, MD5 and SHA-1 are vulnerable to collision attacks, NULL suites provide no encryption, and export-grade ciphers use intentionally short keys breakable by FREAK and LogJam attacks. A suite is marked weak if it uses RSA key exchange (no forward secrecy), 3DES (SWEET32 attack), or CBC mode with SHA-1 HMAC (BEAST and Lucky 13).

Can I look up a cipher suite by its IANA hex code?

Yes. Enter a 4-digit hex value like 0xC02F or just C02F. The tool maps it to the official IANA cipher suite name and then decodes all components. The built-in registry covers the most widely deployed suites; for lesser-known codes, enter the full name directly as the IANA registry is the authoritative source.