encrypt decrypt

crypt.go

package main

import (
    "crypto/aes"
    "crypto/cipher"
    "crypto/sha256"
    "encoding/base64"
    "encoding/hex"
    "fmt"
)

var (
    KEY = []byte("rappier_simple_secret_key")
    IV  = []byte("rappier_simple_secret_iv")
)

func main() {

    h := sha256.New()
    h.Write(KEY)
    KEY = h.Sum(nil)

    h.Reset()
    h.Write(IV)
    IV = h.Sum(nil)[:16]

   fmt.Println("Key", hex.EncodeToString(KEY))
   fmt.Println("IV", hex.EncodeToString(IV))

   // This ciphertext was generated by the PHP module
   de := "rDAnykzTorR5/SgpdD7slA=="
   q, err := decrypt(KEY, IV, de)

   fmt.Println(string(q), err)
}

// Returns slice of the original data without padding.
func pkcs7Unpad(data []byte, blocklen int) ([]byte, error) {
    if blocklen <= 0 {
        return nil, fmt.Errorf("invalid blocklen %d", blocklen)
    }
    if len(data)%blocklen != 0 || len(data) == 0 {
        return nil, fmt.Errorf("invalid data len %d", len(data))
    }
    padlen := int(data[len(data)-1])
    if padlen > blocklen || padlen == 0 {
        return nil, fmt.Errorf("invalid padding")
    }
   // check padding
   pad := data[len(data)-padlen:]
   for i := 0; i < padlen; i++ {
        if pad[i] != byte(padlen) {
            return nil, fmt.Errorf("invalid padding")
        }
   }

   return data[:len(data)-padlen], nil
}

func decrypt(key []byte, iv []byte, encrypted string) ([]byte, error) {
    data, err := base64.StdEncoding.DecodeString(encrypted)
    if err != nil {
        return nil, err
    }

    if len(data) == 0 || len(data)%aes.BlockSize != 0 {
        return nil, fmt.Errorf("bad blocksize(%v), aes.BlockSize = %v\n", len(data), aes.BlockSize)
    }
    c, err := aes.NewCipher(key)
    if err != nil {
        return nil, err
    }
    cbc := cipher.NewCBCDecrypter(c, iv)
    cbc.CryptBlocks(data, data)
    out, err := pkcs7Unpad(data, aes.BlockSize)
    if err != nil {
        return out, err
    }
    return out, nil
}