# TLS_ECDHE_PSK_WITH_CHACHA20_POLY1305_SHA256 cipher suite

> TLS_ECDHE_PSK_WITH_CHACHA20_POLY1305_SHA256 (0xCC,0xAC): ECDHE/PSK · ChaCha20-Poly1305 · TLS 1.2. ssl.sh rating: Secure. OpenSSL/GnuTLS names and Nginx/Apache config.

Source: https://ssl.sh/ciphers/tls-ecdhe-psk-with-chacha20-poly1305-sha256/
Last updated: 2026-11-10

TLS_ECDHE_PSK_WITH_CHACHA20_POLY1305_SHA256 (0xCC,0xAC) is a cipher suite for TLS 1.2: ECDHE key exchange, PSK authentication, ChaCha20-Poly1305 encryption and AEAD message authentication. ssl.sh rates it Secure.

| Field | Value |
|---|---|
| IANA | TLS_ECDHE_PSK_WITH_CHACHA20_POLY1305_SHA256 |
| Hex code | 0xCC,0xAC |
| OpenSSL | ECDHE-PSK-CHACHA20-POLY1305 |
| GnuTLS | TLS_ECDHE_PSK_CHACHA20_POLY1305 |
| Key exchange | ECDHE |
| Authentication | PSK |
| Encryption | ChaCha20-Poly1305 |
| MAC | AEAD |
| TLS versions | TLS 1.2 |
| Rating | Secure |
| IANA "Recommended" | Y |
| References | RFC 7905 |

## What each component means

A [cipher suite](https://ssl.sh/glossary/cipher-suite/) names the algorithms a client and server agree on in one handshake. TLS_ECDHE_PSK_WITH_CHACHA20_POLY1305_SHA256 combines ECDHE key exchange, PSK authentication, ChaCha20-Poly1305 encryption and AEAD integrity protection. Each part is explained below with its known weaknesses; for the bigger picture see [how cipher suites work](https://ssl.sh/learn/cipher-suites/).

Key exchange: ECDHE_PSK. A [pre-shared key](https://ssl.sh/glossary/psk/) authenticates the peers and an ephemeral [ECDHE](https://ssl.sh/glossary/ecdhe/) share is combined with it, giving [forward secrecy](https://ssl.sh/glossary/forward-secrecy/) without certificates. The first ECDHE_PSK suites came in [RFC 5489](https://www.rfc-editor.org/rfc/rfc5489) (2009); AES-GCM and AES-CCM versions for TLS 1.2 followed in [RFC 8442](https://www.rfc-editor.org/rfc/rfc8442) (2018).

Encryption: [ChaCha20-Poly1305](https://ssl.sh/glossary/chacha20-poly1305/), an [AEAD](https://ssl.sh/glossary/aead/) pairing the ChaCha20 stream cipher (256-bit key) with the Poly1305 authenticator and a 16-byte tag. It is fast and constant-time in plain software, so it is the usual choice for devices without AES instructions. [RFC 7905](https://www.rfc-editor.org/rfc/rfc7905) (2016) brought it to TLS 1.2 and builds the 96-bit nonce by XORing the padded record sequence number with the sender's write IV, so no explicit nonce is sent with each record.

Integrity: there is no separate MAC because the AEAD tag authenticates every record. The SHA256 at the end of the name selects the TLS 1.2 PRF hash used to derive keys and compute the Finished messages.

## Why this rating

- Ephemeral key exchange (forward secrecy) plus an AEAD cipher, the combination TLS 1.2 best practice asks for.

## Which TLS libraries support it

Support for TLS_ECDHE_PSK_WITH_CHACHA20_POLY1305_SHA256 as read from each library's own source code or official documentation on 2026-11-10. “Enabled by default” means the library negotiates it with no configuration; “off by default” means it is implemented but has to be switched on.

| Library | Status | Details |
|---|---|---|
| OpenSSL 3.5 | Implemented | cipher string `ECDHE-PSK-CHACHA20-POLY1305` |
| GnuTLS | Implemented | name `TLS_ECDHE_PSK_CHACHA20_POLY1305`; minimum protocol `TLS 1.2` |
| BoringSSL | Enabled by default | - |
| Go crypto/tls | Not supported | - |
| NSS 3.133 | Not supported | - |
| Firefox | Not supported | - |
| Java 21 (SunJSSE) | Not supported | - |
| Windows Schannel (Windows 11 / Server 2022) | Not supported | - |
| rustls 0.23.46 | Not supported | - |

Enabled by default in 1 of the 9 libraries tracked here: BoringSSL. Also implemented by: OpenSSL 3.5 and GnuTLS.

NSS shows the library's own defaults; Firefox switches every NSS suite off at start-up and re-enables only those with a security.ssl3.* or security.tls13.* preference. Java defaults are derived from the jdk.tls.disabledAlgorithms value Oracle documents for JDK 21, which later updates may extend. The OpenSSL and GnuTLS rows only show whether the suite is implemented.

- [BoringSSL — ssl/ssl_cipher.cc (main)](https://boringssl.googlesource.com/boringssl/+/refs/heads/main/ssl/ssl_cipher.cc) (2026-11-10)
- [Go — src/crypto/tls/cipher_suites.go (master)](https://github.com/golang/go/blob/master/src/crypto/tls/cipher_suites.go) (2026-11-10)
- [Go — src/crypto/tls/defaults.go (master)](https://github.com/golang/go/blob/master/src/crypto/tls/defaults.go) (2026-11-10)
- [NSS — lib/ssl/ssl3con.c (as vendored in Firefox)](https://github.com/mozilla-firefox/firefox/blob/main/security/nss/lib/ssl/ssl3con.c) (2026-11-10)
- [NSS — TAG-INFO](https://github.com/mozilla-firefox/firefox/blob/main/security/nss/TAG-INFO) (2026-11-10)
- [Firefox — security/manager/ssl/nsNSSComponent.cpp](https://github.com/mozilla-firefox/firefox/blob/main/security/manager/ssl/nsNSSComponent.cpp) (2026-11-10)
- [Firefox — modules/libpref/init/StaticPrefList.yaml](https://github.com/mozilla-firefox/firefox/blob/main/modules/libpref/init/StaticPrefList.yaml) (2026-11-10)
- [Oracle — JDK 21 Providers Documentation: SunJSSE Cipher Suites](https://docs.oracle.com/en/java/javase/21/security/oracle-providers.html#GUID-7093246A-31A3-4304-AC5F-5FB6400405E2) (2026-11-10)
- [Oracle — JDK 21 JSSE Reference Guide: jdk.tls.disabledAlgorithms](https://docs.oracle.com/en/java/javase/21/security/java-secure-socket-extension-jsse-reference-guide.html) (2026-11-10)
- [Microsoft Learn — TLS Cipher Suites in Windows 11](https://learn.microsoft.com/en-us/windows/win32/secauthn/tls-cipher-suites-in-windows-11) (2026-11-10)
- [Microsoft Learn — TLS Cipher Suites in Windows Server 2022](https://learn.microsoft.com/en-us/windows/win32/secauthn/tls-cipher-suites-in-windows-server-2022) (2026-11-10)
- [docs.rs — rustls 0.23.46 crypto::aws_lc_rs (default provider)](https://docs.rs/rustls/0.23.46/src/rustls/crypto/aws_lc_rs/mod.rs.html) (2026-11-10)

## History and standards status

TLS_ECDHE_PSK_WITH_CHACHA20_POLY1305_SHA256 (0xCC,0xAC) is registered in the IANA TLS Cipher Suites registry with [RFC 7905](https://www.rfc-editor.org/rfc/rfc7905), “ChaCha20-Poly1305 Cipher Suites for Transport Layer Security (TLS)” (June 2016, Standards Track) as its specification. The registry marks it Recommended (Y).

## Nginx / Apache

Enable

```nginx
ssl_protocols TLSv1.2 TLSv1.3;
ssl_ciphers 'ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-PSK-CHACHA20-POLY1305';
ssl_prefer_server_ciphers off;
```

```apache
SSLProtocol -all +TLSv1.2 +TLSv1.3
SSLCipherSuite ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-PSK-CHACHA20-POLY1305
SSLHonorCipherOrder off
```

Disable

```nginx
ssl_ciphers 'ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:!ECDHE-PSK-CHACHA20-POLY1305';
```

```apache
SSLCipherSuite ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:!ECDHE-PSK-CHACHA20-POLY1305
```


## How to test whether a server accepts it

Offer only TLS_ECDHE_PSK_WITH_CHACHA20_POLY1305_SHA256 with openssl s_client; if the handshake completes, the server accepts it:

```bash
openssl s_client -connect example.com:443 -tls1_2 -cipher ECDHE-PSK-CHACHA20-POLY1305 </dev/null
```

nmap's ssl-enum-ciphers script connects repeatedly, trying one suite at a time, and lists every suite the server accepts with a grade from A to F. Look for TLS_ECDHE_PSK_WITH_CHACHA20_POLY1305_SHA256 in its output:

```bash
nmap --script ssl-enum-ciphers -p 443 example.com
```

To decode a name or hex code, use the [cipher suite lookup](https://ssl.sh/tools/cipher-suite-lookup/); the [SSL checker](https://ssl.sh/tools/ssl-checker/) shows which protocol versions a live server accepts and the cipher suite it negotiates.

## FAQ

### Is TLS_ECDHE_PSK_WITH_CHACHA20_POLY1305_SHA256 secure?

Cryptographically, yes: ssl.sh rates it secure. Ephemeral key exchange (forward secrecy) plus an AEAD cipher, the combination TLS 1.2 best practice asks for.

### Can TLS_ECDHE_PSK_WITH_CHACHA20_POLY1305_SHA256 be used with TLS 1.3?

No. TLS 1.3 has its own suites that name only the AEAD and the hash, and TLS 1.2 suites can't be used in a TLS 1.3 handshake. TLS_ECDHE_PSK_WITH_CHACHA20_POLY1305_SHA256 works with TLS 1.2. The closest TLS 1.3 suite is [TLS_CHACHA20_POLY1305_SHA256](https://ssl.sh/ciphers/tls-chacha20-poly1305-sha256/), which TLS 1.3 combines with a separately negotiated key exchange such as X25519.

### How do I enable TLS_ECDHE_PSK_WITH_CHACHA20_POLY1305_SHA256 in Nginx or Apache?

Add `ECDHE-PSK-CHACHA20-POLY1305` (its OpenSSL name) to `ssl_ciphers` in Nginx or to `SSLCipherSuite` in Apache httpd, keep TLS 1.2 enabled in `ssl_protocols` or `SSLProtocol`, and reload. The full snippet is in the configuration section above.

### Which clients and libraries still support TLS_ECDHE_PSK_WITH_CHACHA20_POLY1305_SHA256?

Out of the box: BoringSSL. Implemented, default state not tracked here: OpenSSL 3.5 and GnuTLS. Not supported: Go crypto/tls, NSS 3.133, Firefox, Java 21 (SunJSSE), Windows Schannel (Windows 11 / Server 2022) and rustls 0.23.46.