64 lines
1.3 KiB
Go
64 lines
1.3 KiB
Go
package domain
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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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"crypto/sha256"
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"encoding/base64"
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"fmt"
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"io"
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)
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// Seal encrypts plaintext with AES-GCM derived from secret.
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func Seal(secret, plaintext string) (string, error) {
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if plaintext == "" {
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return "", nil
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}
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key := sha256.Sum256([]byte(secret))
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block, err := aes.NewCipher(key[:])
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if err != nil {
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return "", 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 "", 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 "", err
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}
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out := gcm.Seal(nonce, nonce, []byte(plaintext), nil)
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return base64.RawURLEncoding.EncodeToString(out), nil
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}
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// Open decrypts Seal output.
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func Open(secret, sealed string) (string, error) {
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if sealed == "" {
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return "", nil
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}
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raw, err := base64.RawURLEncoding.DecodeString(sealed)
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if err != nil {
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return "", err
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}
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key := sha256.Sum256([]byte(secret))
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block, err := aes.NewCipher(key[:])
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if err != nil {
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return "", 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 "", err
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}
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ns := gcm.NonceSize()
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if len(raw) < ns {
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return "", fmt.Errorf("ciphertext too short")
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}
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nonce, ct := raw[:ns], raw[ns:]
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pt, err := gcm.Open(nil, nonce, ct, nil)
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if err != nil {
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return "", err
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}
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return string(pt), nil
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}
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