Docker Content Trust (DCT) provides the ability to use digital signatures for data sent to and received from remote Docker registries. These signatures allow client-side or runtime verification of the integrity and publisher of specific image tags.
- Latest Docker desktop
- Docker hub account
- Docker contrainer image ## Documentation Refer the DCT Documentation here
Make a docker repository for your images
- Go to Docker Hub and sign in with your docker hub account
- Click on Create repository and name it "test"
- It should look something like this.
Do Docker login in your CLI with
- Enter your credentials and you are ready to go.
To Sign a docker image we have first generate a key...
To generate a key run this command in your CLI
docker trust key generate signature
- This "Signature" is the name you will give to your key and it will be saved in your working directory with the .pub extension
- After running this command you will be asked to enter and repeat a passphrase.
To make a signer and add it to your repository run this command
docker trust signer add --key signature.pub [signer's name] [your repository's name]
- The repository name will be something like this --> example/test
- You have to enter and repeat passphrase for root key and repository.
Signing and Pushing images to the repository
- First let's commit our container image.
docker commit [Image ID] [Repository Name]
- You can find the image ID from
- Let's push an unsigned image for reference -First tag the image as unsigned-image
docker image tag [Image ID] [Repository Name]:unsigned-image
- Now push the image with
docker push [Repository Name]:unsigned-image
- Now sign the tag and sign the same image. Tag the image with
docker image tag [Image ID] [Repository Name]:signed-image
Sign the image with
docker trust sign [Repository Name]:signed-image
- You have to again enter the passphrase
For the the further imformation about the signed image run
docker trust inspect --pretty [Repository Name]:signed-image
Push the signed image with
docker push [Repository Name]:signed-image The push refers to repository [docker.io/shakunt/test] 059ff50d778b: Layer already exists c4e64d78638e: Layer already exists 5f70bf18a086: Layer already exists 0cd0f4e90e0c: Layer already exists e4a7f8c5002b: Layer already exists 7cc0623bd7a8: Layer already exists f1859b30ca6b: Layer already exists 6a35d52a66fd: Layer already exists fbd7d5451c69: Layer already exists 4fc242d58285: Layer already exists trust-image-signed: digest: sha256:f6274d55e7ae079737180c7cb5----7387fb6a87297ef486edbc1bb16f4d0 size: 2409
Setting up trust environment and pulling the signed and unsigned images
To set up the trust environment run
Let's pull the images
- unsigned image
docker pull [Repository Name]:unsigned-image No valid trust data for unsigned-image
- Signed image
docker pull [Repository Name]:signed-image Pull (1 of 1): shakunt/test:signed-image@sha256:f6274d55e7ae079737180c7cb5b02f386edbc1bb16f4d0 docker.io/shakunt/test@sha256:f6274d55e7ae079737180c7cb5b02f3767387fb6a87bb16f4d0: Pulling from shakunt/test Digest: sha256:f6274d55e7ae079737180c77fb6a87297ef486edbc1bb16f4d0 Status: Image is up to date for shakunt/test@sha256:f6274d551bb16f4d0 Tagging shakunt/test@sha256:f6274d55e7ae079732f3767387fb6a87297ef486edbc1bb16f4d0 as shakunt/test:signed-image docker.io/shakunt/test:signed-image
Thank u, Hope this post helped you!
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