Quickstart: Cryptography

Get started with the Dapr Cryptography building block

Let’s take a look at the Dapr cryptography building block. In this Quickstart, you’ll create an application that encrypts and decrypts data using the Dapr cryptography APIs. You’ll:

  • Encrypt and then decrypt a short string (using an RSA key), reading the result in-memory, in a Go byte slice.
  • Encrypt and then decrypt a large file (using an AES key), storing the encrypted and decrypted data to files using streams.

Currently, you can experience the cryptography API using the Go SDK.

This quickstart includes a JavaScript application called crypto-quickstart.

Pre-requisites

For this example, you will need:

Step 1: Set up the environment

Clone the sample provided in the Quickstarts repo

git clone https://github.com/dapr/quickstarts.git

In the terminal, from the root directory, navigate to the cryptography sample.

cd cryptography/javascript/sdk

Navigate into the folder with the source code:

cd ./crypto-quickstart

Install the dependencies:

npm install

Step 2: Run the application with Dapr

The application code defines two required keys:

  • Private RSA key
  • A 256-bit symmetric (AES) key

Generate two keys, an RSA key and and AES key using OpenSSL and write these to two files:

mkdir -p keys
# Generate a private RSA key, 4096-bit keys
openssl genpkey -algorithm RSA -pkeyopt rsa_keygen_bits:4096 -out keys/rsa-private-key.pem
# Generate a 256-bit key for AES
openssl rand -out keys/symmetric-key-256 32

Run the Go service app with Dapr:

dapr run --app-id crypto-quickstart --resources-path ../../../components/ -- npm start

Expected output

== APP == 2023-10-25T14:30:50.435Z INFO [GRPCClient, GRPCClient] Opening connection to 127.0.0.1:58173
== APP == == Encrypting message using buffers
== APP == Encrypted the message, got 856 bytes
== APP == == Decrypting message using buffers
== APP == Decrypted the message, got 24 bytes
== APP == The secret is "passw0rd"
== APP == == Encrypting message using streams
== APP == Encrypting federico-di-dio-photography-Q4g0Q-eVVEg-unsplash.jpg to encrypted.out
== APP == Encrypted the message to encrypted.out
== APP == == Decrypting message using streams
== APP == Decrypting encrypted.out to decrypted.out.jpg
== APP == Decrypted the message to decrypted.out.jpg

What happened?

local-storage.yaml

Earlier, you created a directory inside crypto-quickstarts called keys. In the local-storage component YAML, the path metadata maps to the newly created keys directory.

apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
  name: localstorage
spec:
  type: crypto.dapr.localstorage
  version: v1
  metadata:
    - name: path
      # Path is relative to the folder where the example is located
      value: ./keys

index.mjs

The application file encrypts and decrypts messages and files using the RSA and AES keys that you generated. The application creates a new Dapr SDK client:

async function start() {
  const client = new DaprClient({
    daprHost,
    daprPort,
    communicationProtocol: CommunicationProtocolEnum.GRPC,
  });

  // Encrypt and decrypt a message from a buffer
  await encryptDecryptBuffer(client);

  // Encrypt and decrypt a message using streams
  await encryptDecryptStream(client);
}
Encrypting and decrypting a string using the RSA key

Once the client is created, the application encrypts a message:

async function encryptDecryptBuffer(client) {
  // Message to encrypt
  const plaintext = `The secret is "passw0rd"`

  // First, encrypt the message
  console.log("== Encrypting message using buffers");

  const encrypted = await client.crypto.encrypt(plaintext, {
    componentName: "localstorage",
    keyName: "rsa-private-key.pem",
    keyWrapAlgorithm: "RSA",
  });

  console.log("Encrypted the message, got", encrypted.length, "bytes");

The application then decrypts the message:

  // Decrypt the message
  console.log("== Decrypting message using buffers");
  const decrypted = await client.crypto.decrypt(encrypted, {
    componentName: "localstorage",
  });

  console.log("Decrypted the message, got", decrypted.length, "bytes");
  console.log(decrypted.toString("utf8"));

  // ...
}
Encrypt and decrpyt a large file using the AES key

Next, the application encrypts a large image file:

async function encryptDecryptStream(client) {
  // First, encrypt the message
  console.log("== Encrypting message using streams");
  console.log("Encrypting", testFileName, "to encrypted.out");

  await pipeline(
    createReadStream(testFileName),
    await client.crypto.encrypt({
      componentName: "localstorage",
      keyName: "symmetric-key-256",
      keyWrapAlgorithm: "A256KW",
    }),
    createWriteStream("encrypted.out"),
  );

  console.log("Encrypted the message to encrypted.out");

The application then decrypts the large image file:

  // Decrypt the message
  console.log("== Decrypting message using streams");
  console.log("Decrypting encrypted.out to decrypted.out.jpg");
  await pipeline(
    createReadStream("encrypted.out"),
    await client.crypto.decrypt({
      componentName: "localstorage",
    }),
    createWriteStream("decrypted.out.jpg"),
  );

  console.log("Decrypted the message to decrypted.out.jpg");
}

This quickstart includes a Go application called crypto-quickstart.

Pre-requisites

For this example, you will need:

Step 1: Set up the environment

Clone the sample provided in the Quickstarts repo

git clone https://github.com/dapr/quickstarts.git

In the terminal, from the root directory, navigate to the cryptography sample.

cd cryptography/go/sdk

Step 2: Run the application with Dapr

Navigate into the folder with the source code:

cd ./crypto-quickstart

The application code defines two required keys:

  • Private RSA key
  • A 256-bit symmetric (AES) key

Generate two keys, an RSA key and and AES key using OpenSSL and write these to two files:

mkdir -p keys
# Generate a private RSA key, 4096-bit keys
openssl genpkey -algorithm RSA -pkeyopt rsa_keygen_bits:4096 -out keys/rsa-private-key.pem
# Generate a 256-bit key for AES
openssl rand -out keys/symmetric-key-256 32

Run the Go service app with Dapr:

dapr run --app-id crypto-quickstart --resources-path ../../../components/ -- go run .

Expected output

== APP == dapr client initializing for: 127.0.0.1:52407
== APP == Encrypted the message, got 856 bytes
== APP == Decrypted the message, got 24 bytes
== APP == The secret is "passw0rd"
== APP == Wrote decrypted data to encrypted.out
== APP == Wrote decrypted data to decrypted.out.jpg

What happened?

local-storage.yaml

Earlier, you created a directory inside crypto-quickstarts called keys. In the local-storage component YAML, the path metadata maps to the newly created keys directory.

apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
  name: localstorage
spec:
  type: crypto.dapr.localstorage
  version: v1
  metadata:
    - name: path
      # Path is relative to the folder where the example is located
      value: ./keys

app.go

The application file encrypts and decrypts messages and files using the RSA and AES keys that you generated. The application creates a new Dapr SDK client:

func main() {
	// Create a new Dapr SDK client
	client, err := dapr.NewClient()
    
    //...

	// Step 1: encrypt a string using the RSA key, then decrypt it and show the output in the terminal
	encryptDecryptString(client)

	// Step 2: encrypt a large file and then decrypt it, using the AES key
	encryptDecryptFile(client)
}
Encrypting and decrypting a string using the RSA key

Once the client is created, the application encrypts a message:

func encryptDecryptString(client dapr.Client) {
    // ...

	// Encrypt the message
	encStream, err := client.Encrypt(context.Background(),
		strings.NewReader(message),
		dapr.EncryptOptions{
			ComponentName: CryptoComponentName,
			// Name of the key to use
			// Since this is a RSA key, we specify that as key wrapping algorithm
			KeyName:          RSAKeyName,
			KeyWrapAlgorithm: "RSA",
		},
	)

    // ...

	// The method returns a readable stream, which we read in full in memory
	encBytes, err := io.ReadAll(encStream)
    // ...

	fmt.Printf("Encrypted the message, got %d bytes\n", len(encBytes))

The application then decrypts the message:

	// Now, decrypt the encrypted data
	decStream, err := client.Decrypt(context.Background(),
		bytes.NewReader(encBytes),
		dapr.DecryptOptions{
			// We just need to pass the name of the component
			ComponentName: CryptoComponentName,
			// Passing the name of the key is optional
			KeyName: RSAKeyName,
		},
	)

    // ...

	// The method returns a readable stream, which we read in full in memory
	decBytes, err := io.ReadAll(decStream)

    // ...

	// Print the message on the console
	fmt.Printf("Decrypted the message, got %d bytes\n", len(decBytes))
	fmt.Println(string(decBytes))
}
Encrypt and decrpyt a large file using the AES key

Next, the application encrypts a large image file:

func encryptDecryptFile(client dapr.Client) {
	const fileName = "liuguangxi-66ouBTTs_x0-unsplash.jpg"

	// Get a readable stream to the input file
	plaintextF, err := os.Open(fileName)

    // ...

	defer plaintextF.Close()

	// Encrypt the file
	encStream, err := client.Encrypt(context.Background(),
		plaintextF,
		dapr.EncryptOptions{
			ComponentName: CryptoComponentName,
			// Name of the key to use
			// Since this is a symmetric key, we specify AES as key wrapping algorithm
			KeyName:          SymmetricKeyName,
			KeyWrapAlgorithm: "AES",
		},
	)

    // ...

	// Write the encrypted data to a file "encrypted.out"
	encryptedF, err := os.Create("encrypted.out")

    // ...

	encryptedF.Close()

	fmt.Println("Wrote decrypted data to encrypted.out")

The application then decrypts the large image file:

	// Now, decrypt the encrypted data
	// First, open the file "encrypted.out" again, this time for reading
	encryptedF, err = os.Open("encrypted.out")

    // ...

	defer encryptedF.Close()

	// Now, decrypt the encrypted data
	decStream, err := client.Decrypt(context.Background(),
		encryptedF,
		dapr.DecryptOptions{
			// We just need to pass the name of the component
			ComponentName: CryptoComponentName,
			// Passing the name of the key is optional
			KeyName: SymmetricKeyName,
		},
	)

    // ...

	// Write the decrypted data to a file "decrypted.out.jpg"
	decryptedF, err := os.Create("decrypted.out.jpg")

    // ...

	decryptedF.Close()

	fmt.Println("Wrote decrypted data to decrypted.out.jpg")
}

Watch the demo

Watch this demo video of the cryptography API from the Dapr Community Call #83:

Tell us what you think!

We’re continuously working to improve our Quickstart examples and value your feedback. Did you find this Quickstart helpful? Do you have suggestions for improvement?

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Next steps

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Last modified July 18, 2025: Upgrade hugo docsy into 1.16 (#4733) (b2fdd345)