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// Copyright 2023 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package keyset_test
// [START encrypted-keyset-example]
import (
"bytes"
"fmt"
"log"
"github.com/tink-crypto/tink-go/v2/aead"
"github.com/tink-crypto/tink-go/v2/keyset"
"github.com/tink-crypto/tink-go/v2/testing/fakekms"
)
// The fake KMS should only be used in tests. It is not secure.
const keyURI = "fake-kms://CM2b3_MDElQKSAowdHlwZS5nb29nbGVhcGlzLmNvbS9nb29nbGUuY3J5cHRvLnRpbmsuQWVzR2NtS2V5EhIaEIK75t5L-adlUwVhWvRuWUwYARABGM2b3_MDIAE"
func Example_encryptedKeyset() {
// Get a KEK (key encryption key) AEAD. This is usually a remote AEAD to a KMS. In this example,
// we use a fake KMS to avoid making RPCs.
client, err := fakekms.NewClient(keyURI)
if err != nil {
log.Fatal(err)
}
kekAEAD, err := client.GetAEAD(keyURI)
if err != nil {
log.Fatal(err)
}
// Generate a new keyset handle for the primitive we want to use.
newHandle, err := keyset.NewHandle(aead.AES256GCMKeyTemplate())
if err != nil {
log.Fatal(err)
}
// Choose some associated data. This is the context in which the keyset will be used.
keysetAssociatedData := []byte("keyset encryption example")
// Encrypt the keyset with the KEK AEAD and the associated data.
buf := new(bytes.Buffer)
writer := keyset.NewBinaryWriter(buf)
err = newHandle.WriteWithAssociatedData(writer, kekAEAD, keysetAssociatedData)
if err != nil {
log.Fatal(err)
}
encryptedKeyset := buf.Bytes()
// The encrypted keyset can now be stored.
// To use the primitive, we first need to decrypt the keyset. We use the same
// KEK AEAD and the same associated data that we used to encrypt it.
reader := keyset.NewBinaryReader(bytes.NewReader(encryptedKeyset))
handle, err := keyset.ReadWithAssociatedData(reader, kekAEAD, keysetAssociatedData)
if err != nil {
log.Fatal(err)
}
// Get the primitive.
primitive, err := aead.New(handle)
if err != nil {
log.Fatal(err)
}
// Use the primitive.
plaintext := []byte("message")
associatedData := []byte("example encryption")
ciphertext, err := primitive.Encrypt(plaintext, associatedData)
if err != nil {
log.Fatal(err)
}
decrypted, err := primitive.Decrypt(ciphertext, associatedData)
if err != nil {
log.Fatal(err)
}
fmt.Println(string(decrypted))
// Output: message
}
// [END encrypted-keyset-example]
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