239e2c214c
- Encrypt/Decrypt using AES-256-GCM with random nonce prepended to ciphertext - ErrCiphertextTooShort sentinel error for malformed ciphertext - DeriveKey using Argon2id RFC 9106 params (time=1, mem=64MB, threads=4, keyLen=32) - NewSalt generates cryptographically random 16-byte salt
53 lines
1.4 KiB
Go
53 lines
1.4 KiB
Go
package storage
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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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// ErrCiphertextTooShort is returned when ciphertext is shorter than the GCM nonce size.
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var ErrCiphertextTooShort = errors.New("ciphertext too short")
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// Encrypt encrypts plaintext using AES-256-GCM with a random nonce.
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// The nonce is prepended to the returned ciphertext.
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// key must be exactly 32 bytes (AES-256).
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func Encrypt(plaintext []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, 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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// Seal appends encrypted data to nonce, so nonce is prepended
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ciphertext := gcm.Seal(nonce, nonce, plaintext, nil)
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return ciphertext, nil
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}
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// Decrypt decrypts ciphertext produced by Encrypt.
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// Expects the nonce to be prepended to the ciphertext.
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func Decrypt(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, 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, ErrCiphertextTooShort
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}
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nonce, ciphertext := ciphertext[:nonceSize], ciphertext[nonceSize:]
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return gcm.Open(nil, nonce, ciphertext, nil)
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}
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