85 lines
1.7 KiB
Go
85 lines
1.7 KiB
Go
// Playbook - http://play.golang.org/p/3wFl4lacjX
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package goaes
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import (
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"bytes"
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"crypto/aes"
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"crypto/cipher"
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"crypto/rand"
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"errors"
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"io"
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"strings"
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)
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func addBase64Padding(value string) string {
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m := len(value) % 4
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if m != 0 {
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value += strings.Repeat("=", 4-m)
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}
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return value
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}
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func removeBase64Padding(value string) string {
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return strings.Replace(value, "=", "", -1)
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}
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func Pad(src []byte) []byte {
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padding := aes.BlockSize - len(src)%aes.BlockSize
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padtext := bytes.Repeat([]byte{byte(padding)}, padding)
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return append(src, padtext...)
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}
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func Unpad(src []byte) ([]byte, error) {
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length := len(src)
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unpadding := int(src[length-1])
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if unpadding > length {
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return nil, errors.New("unpad error. This could happen when incorrect encryption key is used")
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}
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return src[:(length - unpadding)], nil
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}
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func Encrypt(key []byte, text []byte) ([]byte, error) {
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block, err := aes.NewCipher(key)
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if err != nil {
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return nil, err
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}
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msg := Pad(text)
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ciphertext := make([]byte, aes.BlockSize+len(msg))
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iv := ciphertext[:aes.BlockSize]
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if _, err := io.ReadFull(rand.Reader, iv); err != nil {
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return nil, err
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}
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cfb := cipher.NewCFBEncrypter(block, iv)
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cfb.XORKeyStream(ciphertext[aes.BlockSize:], []byte(msg))
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return ciphertext, nil
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}
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func Decrypt(key []byte, text []byte) ([]byte, error) {
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block, err := aes.NewCipher(key)
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if err != nil {
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return nil, err
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}
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if (len(text) % aes.BlockSize) != 0 {
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return nil, errors.New("blocksize must be multipe of decoded message length")
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}
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iv := text[:aes.BlockSize]
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msg := text[aes.BlockSize:]
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cfb := cipher.NewCFBDecrypter(block, iv)
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cfb.XORKeyStream(msg, msg)
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unpadMsg, err := Unpad(msg)
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if err != nil {
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return nil, err
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}
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return unpadMsg, nil
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}
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