60 lines
1.4 KiB
Go
60 lines
1.4 KiB
Go
package settings
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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 seal(plaintext []byte, key []byte) (nonce []byte, ciphertext []byte, err error) {
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block, err := aes.NewCipher(key)
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if err != nil {
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return nil, nil, fmt.Errorf("aes cipher: %w", 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, nil, fmt.Errorf("gcm: %w", 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, nil, fmt.Errorf("nonce: %w", err)
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}
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ciphertext = gcm.Seal(nil, nonce, plaintext, nil)
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return nonce, ciphertext, nil
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}
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func open(nonce []byte, ciphertext []byte, key []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, fmt.Errorf("aes cipher: %w", 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, fmt.Errorf("gcm: %w", err)
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}
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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, fmt.Errorf("decrypt: %w", err)
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}
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return plaintext, nil
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}
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func decodeKey(base64Key string) ([]byte, error) {
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key, err := base64.StdEncoding.DecodeString(base64Key)
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if err != nil {
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return nil, fmt.Errorf("decode key: %w", err)
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}
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if length := len(key); length != 16 && length != 24 && length != 32 {
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return nil, fmt.Errorf("key must be 16, 24, or 32 bytes after base64 decode, got %d", length)
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}
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return key, nil
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}
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