/
awskms.go
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/
awskms.go
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// Copyright © 2018 Banzai Cloud
//
// 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 awskms
import (
"strings"
"emperror.dev/errors"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/aws/session"
"github.com/aws/aws-sdk-go/service/kms"
"github.com/bank-vaults/bank-vaults/pkg/kv"
)
const (
// SseAES256 is an algorithm that can be used for Server-Side Encryption in AWS S3 buckets
SseAES256 string = "AES256"
// SseKMS is an algorithm that can be used for Server-Side Encryption in AWS S3 buckets
SseKMS string = "aws:kms"
)
type awsKMS struct {
store kv.Service
kmsService *kms.KMS
kmsID string
encryptionContext map[string]*string
}
var _ kv.Service = &awsKMS{}
// NewWithSession creates a new kv.Service encrypted by AWS KMS with and existing AWS Session
func NewWithSession(sess *session.Session, store kv.Service, kmsID string, encryptionContext map[string]string) (kv.Service, error) {
if kmsID == "" {
return nil, errors.Errorf("invalid kmsID specified: '%s'", kmsID)
}
return &awsKMS{
store: store,
kmsService: kms.New(sess),
kmsID: kmsID,
encryptionContext: aws.StringMap(encryptionContext),
}, nil
}
// New creates a new kv.Service encrypted by AWS KMS
func New(store kv.Service, region string, kmsID string, encryptionContext map[string]string) (kv.Service, error) {
sess := session.Must(session.NewSession(aws.NewConfig().WithRegion(region)))
return NewWithSession(sess, store, kmsID, encryptionContext)
}
func (a *awsKMS) decrypt(cipherText []byte) ([]byte, error) {
out, err := a.kmsService.Decrypt(&kms.DecryptInput{
KeyId: aws.String(a.kmsID),
CiphertextBlob: cipherText,
EncryptionContext: a.encryptionContext,
GrantTokens: []*string{},
})
if err != nil {
return nil, errors.WrapIf(err, "failed to decrypt with KMS client")
}
trimKey := strings.TrimSpace(string(out.Plaintext))
return []byte(trimKey), nil
}
func (a *awsKMS) Get(key string) ([]byte, error) {
cipherText, err := a.store.Get(key)
if err != nil {
return nil, errors.WrapIf(err, "failed to get data for KMS client")
}
return a.decrypt(cipherText)
}
func (a *awsKMS) encrypt(plainText []byte) ([]byte, error) {
out, err := a.kmsService.Encrypt(&kms.EncryptInput{
KeyId: aws.String(a.kmsID),
Plaintext: plainText,
EncryptionContext: a.encryptionContext,
GrantTokens: []*string{},
})
if err != nil {
return nil, errors.WrapIf(err, "failed to encrypt with KMS client")
}
return out.CiphertextBlob, nil
}
func (a *awsKMS) Set(key string, val []byte) error {
cipherText, err := a.encrypt(val)
if err != nil {
return err
}
return a.store.Set(key, cipherText)
}