/
decrypter.go
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/
decrypter.go
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/*
* Copyright 2024 CoreLayer BV
*
* 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 cryptostruct
import (
"bytes"
"encoding/hex"
"fmt"
"reflect"
"github.com/minio/sio"
)
func Decrypt(key string, data DecryptTransformer) (any, error) {
return NewDecrypter(hex.EncodeToString([]byte(key)), data.GetTransformConfig()).Transform(data)
}
func NewDecrypter(masterKeyHex string, c TransformConfig) Decrypter {
return Decrypter{
key: masterKeyHex,
config: c,
}
}
type Decrypter struct {
key string
config TransformConfig
}
func (t Decrypter) Transform(r DecryptTransformer) (any, error) {
var (
err error
tags map[string]Tag
output any
cryptoConfig sio.Config
)
// Get input type and value of r
inputType := reflect.TypeOf(r)
inputValue := reflect.ValueOf(r)
// // Get CryptoParams from input
cryptoConfig, err = r.GetCryptoParams().GetCryptoConfig(t.key)
if err != nil {
return nil, fmt.Errorf("could not initialize crypto parameters: %w", err)
}
// Get the struct tags for r
tags, err = getTags(r)
if err != nil {
return nil, fmt.Errorf("could not get tags: %w", err)
}
// Get struct to which data must be converted
output = t.config.Decrypted
// To be able to set the fields for the output, we need to get the Value of the output pointer
outputValue := reflect.ValueOf(&output).Elem()
// To be able to mutate the outputValue, we must first get a temporary outputValue
tmp := reflect.New(outputValue.Elem().Type()).Elem()
tmp.Set(outputValue.Elem())
// Process all fields in r
for i := 0; i < inputValue.NumField(); i++ {
fieldName := inputType.Field(i).Name
fieldType := inputType.Field(i).Type
fieldValue := inputValue.Field(i)
// CryptoParams must not be stored in the output
if fieldType == reflect.TypeOf(CryptoParams{}) {
continue
}
// If field tag is not enabled, copy the value to the output
if !tags[fieldName].Enabled {
tmp.FieldByName(fieldName).Set(fieldValue)
continue
}
// Decrypt current field
var decryptedValue reflect.Value
switch inputValue.Field(i).Kind() {
case reflect.Slice:
if decryptedValue, err = t.decryptSlice(fieldValue, tmp.FieldByName(fieldName).Type(), cryptoConfig); err != nil {
return nil, err
}
default:
if decryptedValue, err = t.decryptFields(fieldType, fieldValue, tmp.FieldByName(fieldName).Kind(), cryptoConfig); err != nil {
return nil, err
}
}
tmp.FieldByName(fieldName).Set(decryptedValue)
}
outputValue.Set(tmp)
return output, nil
}
func (t Decrypter) decryptSlice(inputValue reflect.Value, outputType reflect.Type, cryptoConfig sio.Config) (reflect.Value, error) {
var (
err error
output reflect.Value
)
// Create a slice of the outputType with the correct capacity
output = reflect.MakeSlice(outputType, 0, 0)
// Loop over the input slice and encrypt each element
for i := 0; i < inputValue.Len(); i++ {
var decryptedValue reflect.Value
if decryptedValue, err = t.decryptFields(reflect.TypeOf(inputValue.Index(i).Interface()), inputValue.Index(i), outputType.Elem().Kind(), cryptoConfig); err != nil {
return reflect.Value{}, err
}
// Append the decrypted value to the output
output = reflect.Append(output, decryptedValue)
}
return output, nil
}
func (t Decrypter) decryptFields(fieldType reflect.Type, fieldValue reflect.Value, outputKind reflect.Kind, cryptoConfig sio.Config) (reflect.Value, error) {
var (
err error
out reflect.Value
)
// Check if the fieldType implements interface DecryptTransformer
if fieldType.Implements(reflect.TypeOf((*DecryptTransformer)(nil)).Elem()) {
if out, err = t.decryptStruct(fieldValue); err != nil {
return reflect.Value{}, err
}
} else {
// Decode fieldValue from hex encoded string to []byte
var source []byte
source, err = hex.DecodeString(fieldValue.String())
if err != nil {
return reflect.Value{}, err
}
encryptedDataReader := bytes.NewReader(source)
decryptedDataWriter := bytes.NewBuffer(make([]byte, 0))
// Decrypt data in encryptedDataReader into decryptedDataWriter using cryptoconfig
if _, err = sio.Decrypt(decryptedDataWriter, encryptedDataReader, cryptoConfig); err != nil {
return reflect.Value{}, fmt.Errorf("failed to decrypt data: %w", err)
}
// Convert decrypted data from hex string to desired output type
out, err = convertHexStringToValue(decryptedDataWriter.String(), outputKind)
if err != nil {
return reflect.Value{}, err
}
}
return out, nil
}
func (t Decrypter) decryptStruct(field reflect.Value) (reflect.Value, error) {
var (
err error
decrypter Decrypter
output any
)
decrypter = NewDecrypter(t.key, getEmbeddedTransformConfig(field))
if output, err = decrypter.Transform(field.Interface().(DecryptTransformer)); err != nil {
return reflect.Value{}, err
}
return reflect.ValueOf(output), nil
}