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encrypt_symmetric.go
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/
encrypt_symmetric.go
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// Copyright 2020 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
//
// https://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 kms
// [START kms_encrypt_symmetric]
import (
"context"
"fmt"
"hash/crc32"
"io"
kms "cloud.google.com/go/kms/apiv1"
"cloud.google.com/go/kms/apiv1/kmspb"
"google.golang.org/protobuf/types/known/wrapperspb"
)
// encryptSymmetric encrypts the input plaintext with the specified symmetric
// Cloud KMS key.
func encryptSymmetric(w io.Writer, name string, message string) error {
// name := "projects/my-project/locations/us-east1/keyRings/my-key-ring/cryptoKeys/my-key"
// message := "Sample message"
// Create the client.
ctx := context.Background()
client, err := kms.NewKeyManagementClient(ctx)
if err != nil {
return fmt.Errorf("failed to create kms client: %w", err)
}
defer client.Close()
// Convert the message into bytes. Cryptographic plaintexts and
// ciphertexts are always byte arrays.
plaintext := []byte(message)
// Optional but recommended: Compute plaintext's CRC32C.
crc32c := func(data []byte) uint32 {
t := crc32.MakeTable(crc32.Castagnoli)
return crc32.Checksum(data, t)
}
plaintextCRC32C := crc32c(plaintext)
// Build the request.
req := &kmspb.EncryptRequest{
Name: name,
Plaintext: plaintext,
PlaintextCrc32C: wrapperspb.Int64(int64(plaintextCRC32C)),
}
// Call the API.
result, err := client.Encrypt(ctx, req)
if err != nil {
return fmt.Errorf("failed to encrypt: %w", err)
}
// Optional, but recommended: perform integrity verification on result.
// For more details on ensuring E2E in-transit integrity to and from Cloud KMS visit:
// https://cloud.google.com/kms/docs/data-integrity-guidelines
if result.VerifiedPlaintextCrc32C == false {
return fmt.Errorf("Encrypt: request corrupted in-transit")
}
if int64(crc32c(result.Ciphertext)) != result.CiphertextCrc32C.Value {
return fmt.Errorf("Encrypt: response corrupted in-transit")
}
fmt.Fprintf(w, "Encrypted ciphertext: %s", result.Ciphertext)
return nil
}
// [END kms_encrypt_symmetric]