91 lines
2.3 KiB
Go
91 lines
2.3 KiB
Go
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package aes
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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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"encoding/base64"
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"encoding/json"
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"fmt"
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"io"
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)
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// PKCS7Padding pads an input slice to be a multiple of the block size.
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func PKCS7Padding(ciphertext []byte, blockSize int) []byte {
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padding := blockSize - len(ciphertext)%blockSize
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padtext := bytes.Repeat([]byte{byte(padding)}, padding)
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return append(ciphertext, padtext...)
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}
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// PKCS7UnPadding removes the padding from a padded ciphertext.
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func PKCS7UnPadding(origData []byte) ([]byte, error) {
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length := len(origData)
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unpadding := int(origData[length-1])
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if unpadding > length {
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return nil, fmt.Errorf("unpadding size is invalid")
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}
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return origData[:(length - unpadding)], nil
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}
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// Encrypt encrypts a string to an encrypted string.
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func Encrypt(key, text string) (string, error) {
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block, err := aes.NewCipher([]byte(key))
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if err != nil {
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return "", err
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}
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b := base64.StdEncoding.EncodeToString([]byte(text))
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ciphertext := make([]byte, aes.BlockSize+len(b))
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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 "", err
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}
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stream := cipher.NewCFBEncrypter(block, iv)
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stream.XORKeyStream(ciphertext[aes.BlockSize:], []byte(b))
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ciphertext = PKCS7Padding(ciphertext, aes.BlockSize)
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return base64.StdEncoding.EncodeToString(ciphertext), nil
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}
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// Decrypt decrypts an encrypted string to an original string.
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func Decrypt(key, cryptoText string) (string, error) {
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ciphertext, _ := base64.StdEncoding.DecodeString(cryptoText)
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ciphertext, err := PKCS7UnPadding(ciphertext)
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if err != nil {
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return "", err
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}
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block, err := aes.NewCipher([]byte(key))
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if err != nil {
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return "", err
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}
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if len(ciphertext) < aes.BlockSize {
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return "", fmt.Errorf("ciphertext too short")
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}
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iv := ciphertext[:aes.BlockSize]
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ciphertext = ciphertext[aes.BlockSize:]
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stream := cipher.NewCFBDecrypter(block, iv)
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stream.XORKeyStream(ciphertext, ciphertext)
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result, err := base64.StdEncoding.DecodeString(string(ciphertext))
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if err != nil {
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return "", err
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}
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return string(result), nil
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}
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// EncryptType encrypts a type to an encrypted string.
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// Note: This assumes the type can be marshaled to JSON.
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func EncryptType(key string, data interface{}) (string, error) {
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jsonData, err := json.Marshal(data)
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if err != nil {
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return "", err
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}
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return Encrypt(key, string(jsonData))
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}
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