104 lines
1.9 KiB
Go
104 lines
1.9 KiB
Go
package cm509
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import (
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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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"fmt"
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"io"
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)
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func EncryptAES256(b64data string, key string) (string, error) {
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var res string
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var err error
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const aes256KeyLen = 32
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bKey := []byte(key)
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keyLen := len(bKey)
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switch {
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case keyLen > aes256KeyLen:
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bKey = bKey[:aes256KeyLen]
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case keyLen < aes256KeyLen:
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padding := make([]byte, aes256KeyLen-keyLen)
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bKey = append(bKey, padding...)
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case keyLen == 0:
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return res, fmt.Errorf("Zero lenght key")
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}
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data, err := base64.StdEncoding.DecodeString(b64data)
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if err != nil {
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return res, err
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}
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block, err := aes.NewCipher(bKey)
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if err != nil {
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return res, err
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}
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nonce := make([]byte, 12)
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_, err = io.ReadFull(rand.Reader, nonce)
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if err != nil {
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return res, err
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}
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aesgcm, err := cipher.NewGCM(block)
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if err != nil {
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return res, err
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}
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ciphertext := aesgcm.Seal(nil, nonce, data, nil)
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ciphertext = append(nonce, ciphertext...)
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res = base64.StdEncoding.EncodeToString(ciphertext)
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return res, err
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}
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func DecryptAES256(b64ciphertext string, key string) (string, error) {
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var res string
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var err error
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const aes256KeyLen = 32
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bKey := []byte(key)
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keyLen := len(bKey)
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switch {
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case keyLen > aes256KeyLen:
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bKey = bKey[:aes256KeyLen]
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case keyLen < aes256KeyLen:
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padding := make([]byte, aes256KeyLen-keyLen)
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bKey = append(bKey, padding...)
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case keyLen == 0:
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return res, fmt.Errorf("Zero lenght key")
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}
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ciphertext, err := base64.StdEncoding.DecodeString(b64ciphertext)
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if err != nil {
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return res, err
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}
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block, err := aes.NewCipher(bKey)
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if err != nil {
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return res, err
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}
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aesgcm, err := cipher.NewGCM(block)
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if err != nil {
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return res, err
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}
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nonceSize := aesgcm.NonceSize()
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nonce, ciphertext := ciphertext[:nonceSize], ciphertext[nonceSize:]
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plaintext, err := aesgcm.Open(nil, nonce, ciphertext, nil)
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if err != nil {
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return res, err
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}
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res = base64.StdEncoding.EncodeToString(plaintext)
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return res, err
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}
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