63 lines
1.2 KiB
Go
63 lines
1.2 KiB
Go
package encrypt
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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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"errors"
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"io"
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)
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var tooShort = errors.New("Too Short")
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type Message struct {
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Data []byte
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}
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// NOTE: should use only 32 byte key
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// key can be derived via hkdf package
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func Encrypt(plaintext, key []byte) (*Message, 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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gcm, err := cipher.NewGCM(block)
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if err != nil {
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return nil, err
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}
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nonce := make([]byte, gcm.NonceSize())
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if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
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return nil, err
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}
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ciphertext := gcm.Seal(nil, nonce, plaintext, nil)
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return &Message{
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Data: append(nonce, ciphertext...),
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}, nil
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}
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// NOTE: should use only 32 byte key
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// key can be derived via hkdf package
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func Decrypt(ciphertext, key []byte) (*Message, 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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gcm, err := cipher.NewGCM(block)
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if err != nil {
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return nil, err
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}
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nonceSize := gcm.NonceSize()
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if len(ciphertext) < nonceSize {
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return nil, tooShort
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}
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nonce, ciphertext := ciphertext[:nonceSize], ciphertext[nonceSize:]
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plaintext, err := gcm.Open(nil, nonce, ciphertext, nil)
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if err != nil {
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return nil, err
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}
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return &Message{
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Data: plaintext,
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}, nil
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}
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