use json unmarshal/marshal from jsoniter in hotpaths (#12269)

cmd/config/crypto.go

@@ -21,11 +21,11 @@ import (
 	"bytes"
 	"crypto/rand"
 	"encoding/binary"
-	"encoding/json"
 	"errors"
 	"fmt"
 	"io"
 
+	jsoniter "github.com/json-iterator/go"
 	"github.com/minio/minio/pkg/fips"
 	"github.com/minio/minio/pkg/kms"
 	"github.com/secure-io/sio-go"
@@ -88,6 +88,7 @@ func Encrypt(KMS kms.KMS, plaintext io.Reader, context kms.Context) (io.Reader,
 		header [5]byte
 		buffer bytes.Buffer
 	)
+	var json = jsoniter.ConfigCompatibleWithStandardLibrary
 	metadata, err := json.Marshal(encryptedObject{
 		KeyID:     key.KeyID,
 		KMSKey:    key.Ciphertext,
@@ -139,6 +140,7 @@ func Decrypt(KMS kms.KMS, ciphertext io.Reader, context kms.Context) (io.Reader,
 	if _, err := io.ReadFull(ciphertext, metadataBuffer); err != nil {
 		return nil, err
 	}
+	var json = jsoniter.ConfigCompatibleWithStandardLibrary
 	if err := json.Unmarshal(metadataBuffer, &metadata); err != nil {
 		return nil, err
 	}