metarare_api-main/helpers/gauth/aes.go

package gauth

import (
	"crypto/aes"
	"fmt"
	"strings"

	b64 "encoding/base64"

	"github.com/happierall/l"
	"github.com/metarare/metarare_api/helpers"
)

func prepareForAES() (string, error) {

	vv := helpers.LoadEnvs()
	v := vv.GetString("jwt.aes_secret")

	if strings.Compare(v, "") != 0 {
		return v, nil
	} else {
		l.Error("There is no JWTKey ")
		return "", fmt.Errorf("Threr is no AES SECRET!!!")
	}
}

func encrpyt(plainText string) ([]byte, error) {
	k, err := prepareForAES()
	if err != nil {
		l.Error(err.Error())
		return nil, err
	}
	if len(k) < len(plainText) {
		err := fmt.Errorf("Plain text is too long...(Max size %d)", len(k))
		l.Errorf(err.Error())
		return nil, err
	}
	if len(plainText) > 255 {
		err := fmt.Errorf("Plain data is too long MAX SIZE is 255")
		l.Errorf(err.Error())
		return nil, err
	}
	tempData := []byte(k[:aes.BlockSize])
	block, err := aes.NewCipher(tempData)
	if err != nil {
		l.Error(err)
		return nil, err
	}

	devidedText := make([]string, len(plainText)/aes.BlockSize+1)
	lastBlockSize := len(plainText) % aes.BlockSize

	for i := 0; i < len(devidedText)-1; i++ {
		devidedText[i] = plainText[i*aes.BlockSize : (i+1)*aes.BlockSize]
	}
	padding := make([]byte, aes.BlockSize-lastBlockSize)
	devidedText[len(devidedText)-1] = fmt.Sprintf("%s%s", plainText[aes.BlockSize*(len(devidedText)-1):len(plainText)], string(padding))
	// NOTE It work good even if doesn't do initializing why?
	//devidedText[len(devidedText)-1 ] = append( devidedText[len(devidedText)-1 ], padding)

	prefix := make([]byte, 1) // 마지막 블럭의 사이즈
	prefix[0] = byte(lastBlockSize) & 0xff
	//encData := string(prefix)
	encData := prefix

	//store := make([]byte, aes.BlockSize*len(devidedText)+1)
	store := make([]byte, aes.BlockSize)
	for i := range devidedText {
		block.Encrypt(store, []byte(devidedText[i]))
		//encData = encData + string(store)
		encData = append(encData, store...)
		// l.Log("block data : (%s) , totalString (%s)", store, encData)
	}

	//return fmt.Sprintf("%s", encData), nil
	return encData, nil
}

func E(text string) []byte {
	if v, err := encrpyt(text); err != nil {
		l.Error("invalid value")
		return nil
	} else {
		return v
	}
}

func Pack(raw string) string {
	encData := E(raw)
	b64EncData := b64.URLEncoding.EncodeToString(encData)
	return b64EncData
}

func decrpyt(encData string) ([]byte, error) {
	k, err := prepareForAES()
	if err != nil {
		return nil, err
	}
	if len(k) < len(encData) {
		err := fmt.Errorf("Plain text is too long...(Max size %d)", len(k))
		l.Errorf(err.Error())
		return nil, err
	}
	if len(encData) > 255 {
		err := fmt.Errorf("Plain data is too long MAX SIZE is 255")
		l.Errorf(err.Error())
		return nil, err
	}
	if len(encData)%aes.BlockSize != 1 {
		// encData size have to fit [len(encData) =16 * n + 1]
		err := fmt.Errorf("encData size have to fit [len(encData) =16 * n + 1]")
		l.Errorf(err.Error())
		return nil, err
	}
	block, err := aes.NewCipher([]byte(k[:aes.BlockSize]))
	if err != nil {
		l.Error(err)
		return nil, err
	}

	lastBlockSize := int([]byte(encData[:1])[0] & 0xff)
	leftEncData := []byte(encData[1:len(encData)])
	/// new
	devidedTextLen := len(leftEncData) / aes.BlockSize
	if len(leftEncData)%aes.BlockSize != 0 {
		devidedTextLen++
	}
	devidedText := make([][]byte, devidedTextLen)
	for i := range devidedText {
		devidedText[i] = leftEncData[aes.BlockSize*i : aes.BlockSize*(i+1)]
	}

	plainBinary := make([]byte, 0)
	store := make([]byte, aes.BlockSize)
	for i := 0; i < devidedTextLen; i++ {
		block.Decrypt(store, []byte(devidedText[i]))
		plainBinary = append(plainBinary, store...)
	}

	return plainBinary[:len(leftEncData)-(aes.BlockSize-lastBlockSize)], nil
}
func D(encData string) []byte {
	if v, err := decrpyt(encData); err != nil {
		l.Error("invalid value")
		return nil
	} else {
		return v
	}
}

func UnPack(b64EncData string) string {
	decoded64Data, _ := b64.URLEncoding.DecodeString(b64EncData)
	decData := D(string(decoded64Data))
	return string(decData)
}