OpenSSL

Container images with the openssl command from OpenSSL, compiled from the signed release tarball of the newest stable series, currently 4.0. The images are rebuilt for each release of the newest series and when the base image changes, for linux/amd64 and linux/arm64.

This is an unofficial build, not affiliated with or endorsed by the OpenSSL Project. Report problems with the image in this repository and problems with OpenSSL itself upstream.

Quick start

docker run --rm --user "$(id -u):$(id -g)" -v "$PWD:/work" \
  ghcr.io/randomcontainers/openssl x509 -in cert.pem -noout -text

Make a key and a self-signed certificate for localhost. Most browsers and TLS libraries ignore the common name and match the host name against subjectAltName, so the command sets both:

docker run --rm --user "$(id -u):$(id -g)" -v "$PWD:/work" \
  ghcr.io/randomcontainers/openssl req -x509 -newkey ec -pkeyopt ec_paramgen_curve:P-256 \
  -noenc -keyout key.pem -out cert.pem -days 30 \
  -subj /CN=localhost -addext subjectAltName=DNS:localhost

See which TLS version, cipher and key exchange a server negotiates:

docker run --rm ghcr.io/randomcontainers/openssl s_client -connect example.org:443 -brief

The entrypoint runs openssl under tini in /work, so file names are relative to the directory you mount. Without arguments the image runs openssl help, which lists the commands. Without -i, the container's standard input is empty, so s_client disconnects right after the handshake. Pass -i to pipe data in (docker run --rm -i ghcr.io/randomcontainers/openssl dgst -sha256 < file), and -it for an interactive s_client session or a passphrase prompt. The manual pages cover every command.

Post-quantum algorithms and ECH

OpenSSL's default group list puts the hybrid post-quantum group X25519MLKEM768 first, so s_client -brief prints Negotiated TLS1.3 group: X25519MLKEM768 when a server supports it. Pass -groups X25519MLKEM768 to offer nothing else. ML-DSA and SLH-DSA keys and certificates work with the usual commands:

docker run --rm --user "$(id -u):$(id -g)" -v "$PWD:/work" \
  ghcr.io/randomcontainers/openssl genpkey -algorithm ML-DSA-65 -out mldsa.key

OpenSSL 4.0 adds Encrypted Client Hello (ECH, RFC 9849). openssl ech -public_name example.com -out ech.pem writes a key pair and its ECHConfigList to ech.pem, and s_server -ech_key ech.pem loads it. s_client -ech_config_list takes the ECHConfigList as one line of base64, so join the lines between BEGIN ECHCONFIG and END ECHCONFIG before passing it:

ecl=$(awk '/END ECHCONFIG/ { p = 0 } p { printf "%s", $0 } /BEGIN ECHCONFIG/ { p = 1 }' ech.pem)
docker run --rm ghcr.io/randomcontainers/openssl s_client -connect <host>:<port> -ech_config_list "$ecl"

With the line breaks left in, s_client stops with error setting ECHConfigList. Without -brief, it reports the result as ECH: success: 1, followed by the inner and outer server names.

Coming from OpenSSL 3

Ubuntu 26.04 and Alpine 3.24 ship OpenSSL 3.5. These changes in 4.0 affect the command line:

• Engines are gone, and with them the -engine options. Use providers instead.
• SSLv3 is removed, and the deprecated elliptic curves of RFC 8422 are no longer available in TLS.
• EC keys with explicit curve parameters fail to load unless the parameters match a named curve.
• c_rehash is removed; openssl rehash does the same job. openssl ca no longer has -msie-hack.
• Hex dumps of key data, such as the RSA modulus in rsa -text, no longer start with an extra 00:, and dumps are 16 bytes wide (24 for signatures). Scripts that parse -text output may need changes.
• req, x509 and ca take the subject and authority key identifiers from the configuration file. The stock openssl.cnf in this image adds them.

NEWS.md lists all incompatible changes in 4.0, including those in the library API.

What is in the image

• openssl in /usr/local/bin, with libssl.so.4 and libcrypto.so.4 in /usr/local/lib.
• The legacy provider, /usr/local/lib/ossl-modules/legacy.so, for MD4, RC4, Blowfish, DES-X and other old algorithms. Load it with -provider legacy -provider default.
• The OpenSSL directory /usr/local/ssl with the stock openssl.cnf. certs and cert.pem in it point to the distro's CA certificates in /etc/ssl/certs, so s_client and verify trust the same CAs as the rest of the system.

The build uses upstream's default options. QUIC, ECH, ML-KEM, ML-DSA and SLH-DSA are in. The FIPS provider, kernel TLS, zlib, Brotli and zstd compression, MD2 and RC5 are not. The headers, static libraries and pkg-config files are left out, and so are the man pages and the CA.pl and tsget scripts, which need Perl. openssl version -a prints the build settings, and the configure options are in /usr/local/share/randomcontainers/openssl/buildinfo.

The Ubuntu image also has Ubuntu's own OpenSSL 3, /usr/bin/openssl and libssl.so.3, because the ca-certificates package depends on it. /usr/local/bin comes first on the PATH, so openssl runs this build. The Alpine image has Alpine's libssl3 and libcrypto3, which come with the base image, but no second openssl command.

This is an image for the openssl command, not a base image for programs that link OpenSSL. Programs installed from distro packages keep loading the distro's libssl.so.3.

Default or slim

OpenSSL's default image adds no other tools, so latest and slim are the same image: openssl and the libraries it links against. Use latest to run it and the slim tags as a base for your own image.

Tags

<version> is an OpenSSL release such as 4.0.3. <minor> and <major> are its shorter forms, 4.0 and 4, and follow the newest release in that series. Each row lists the default tag and its slim twin, which point to the same image.

Tags	Base
latest, slim	Ubuntu
<version>, <version>-slim	Ubuntu
<minor>, <minor>-slim, <major>, <major>-slim	Ubuntu
ubuntu, slim-ubuntu	Ubuntu
<version>-ubuntu, <version>-slim-ubuntu	Ubuntu
<minor>-ubuntu, <minor>-slim-ubuntu, <major>-ubuntu, <major>-slim-ubuntu	Ubuntu
<version>-ubuntu26.04, <version>-slim-ubuntu26.04	Ubuntu 26.04
alpine, slim-alpine	Alpine
<version>-alpine, <version>-slim-alpine	Alpine
<minor>-alpine, <minor>-slim-alpine, <major>-alpine, <major>-slim-alpine	Alpine
<version>-alpine3.24, <version>-slim-alpine3.24	Alpine 3.24

The images are currently built on Ubuntu 26.04 and Alpine 3.24. Tags without a distro version move to the next distro release when the project does; tags ending in ubuntu26.04 or alpine3.24 stay on that release and are no longer rebuilt once the project moves to the next one. Every tag of the current OpenSSL version, including the exact version, is rebuilt in place (see Updates), so pin a digest when you need the same bytes every time.

Only the newest stable series is built. OpenSSL 4.0 is not a long-term support release: upstream supports it until 2027-05-14, and 4.1 is due before then. When 4.1.0 comes out, latest, 4 and the distro tags move to it, and 4.0 stays on the last 4.0 release built here. Later 4.0 patch releases are not built, so an image on the 4.0 tag gets no more security fixes, from OpenSSL or from the distro. Releases of older series, such as the 3.5 long-term support release, are not built at all.

Platforms

linux/amd64 and linux/arm64, for both Ubuntu and Alpine. Both are compiled natively on GitHub-hosted runners, without emulation.

Files and permissions

The working directory is /work. The image runs as UID 1000, and any other UID works too: HOME is then /, and caches go to /cache, which anyone can write to. How to get output files owned by you depends on how you run containers:

Runtime	Flag
Docker on Linux (rootful), GitHub Actions	--user "$(id -u):$(id -g)"
Rootless Podman	--userns=keep-id
Rootless Docker	--user 0:0 (root in the container is your user on the host)
Docker Desktop on macOS or Windows	none, file ownership is mapped for you

Extending the slim image

Use a slim tag as the base for your own image. slim, slim-ubuntu and slim-alpine move to each new OpenSSL release and are rebuilt when the base image changes. The packages OpenSSL needs are listed in /usr/local/share/randomcontainers/openssl/runtime-deps. Switch to root to change the image, then back. To trust a private CA in s_client and verify:

FROM ghcr.io/randomcontainers/openssl:slim-ubuntu@sha256:...
USER root
COPY my-ca.crt /usr/local/share/ca-certificates/
RUN update-ca-certificates
USER 1000:1000

The same lines work with slim-alpine. The entrypoint is ["tini", "--", "openssl"]; set your own ENTRYPOINT if your image runs something else. To pick up new OpenSSL releases and base image fixes, let Dependabot or Renovate update the digest in your FROM line.

Verifying

Each image has a build provenance attestation from this repository's GitHub Actions run, signed by the shared build workflow in randomcontainers/ci:

gh attestation verify oci://ghcr.io/randomcontainers/openssl:latest \
  --repo randomcontainers/openssl --signer-repo randomcontainers/ci

Each platform image also carries an SPDX SBOM that lists every distro package with its version:

docker buildx imagetools inspect ghcr.io/randomcontainers/openssl:latest --format '{{ json .SBOM }}'

Before compiling, the build checks the tarball against the SHA-256 recorded in package.yml and its signature against the OpenSSL release signing key in keys/openssl-release.gpg (fingerprint B146 647E 45A7 B339 47AB 226B 2A2C 87D1 6169 2D40). Releases are signed with a subkey of it that expires on 2027-05-26.

Updates

The project checks the releases of openssl/openssl every 15 minutes and skips pre-releases. A release is picked up once it is 24 hours old. Its tarball is checked against the release's openssl-<version>.tar.gz.sha256 file and the digest GitHub records for the asset, the new version and the tarball's SHA-256 are committed to package.yml, and the images are rebuilt. A release signed with a key that is not in keys/openssl-release.gpg fails to build until the key is added. OpenSSL usually publishes patch releases of all supported series on the same day, and only the highest version is built; tags of older versions stay as they were last built.

The images of the current version are also rebuilt when the Ubuntu or Alpine base image changes and at least every 7 days, so distro security fixes reach the current tags.

Building

docker build -f Dockerfile.ubuntu --target slim \
  --build-arg VERSION=<version> \
  --build-arg SOURCE_SHA256=<sha256 from package.yml> \
  -t openssl:local .

Use Dockerfile.alpine for the Alpine image. --build-arg JOBS=<n> limits the number of parallel compile jobs.

Licenses

OpenSSL is licensed under the Apache License 2.0, so the image's license label is Apache-2.0. OpenSSL's LICENSE.txt is in /usr/local/share/randomcontainers/openssl/licenses/. The Ubuntu and Alpine packages in the image keep their own licenses.

Every version has a GitHub release in this repository, named v<version>, with the exact openssl-<version>.tar.gz that was compiled and its signature. The build applies no patches. /usr/local/share/randomcontainers/openssl/source lists that release and the upstream download URLs.

The files in this repository are available under the MIT license, see LICENSE.

Requesting a tool

To suggest another tool, use the Request a tool form.