forked from wrenn/wrenn
64 lines
1.5 KiB
Go
64 lines
1.5 KiB
Go
package channels
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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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// EncryptSecret encrypts plaintext using AES-256-GCM with a random nonce.
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// Returns base64(nonce || ciphertext).
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func EncryptSecret(key [32]byte, plaintext string) (string, error) {
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block, err := aes.NewCipher(key[:])
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if err != nil {
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return "", 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 "", 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 "", fmt.Errorf("nonce: %w", err)
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}
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ciphertext := gcm.Seal(nonce, nonce, []byte(plaintext), nil)
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return base64.StdEncoding.EncodeToString(ciphertext), nil
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}
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// DecryptSecret decrypts a value produced by EncryptSecret.
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func DecryptSecret(key [32]byte, encoded string) (string, error) {
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data, err := base64.StdEncoding.DecodeString(encoded)
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if err != nil {
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return "", fmt.Errorf("base64 decode: %w", err)
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}
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block, err := aes.NewCipher(key[:])
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if err != nil {
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return "", 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 "", fmt.Errorf("gcm: %w", err)
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}
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nonceSize := gcm.NonceSize()
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if len(data) < nonceSize {
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return "", fmt.Errorf("ciphertext too short")
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}
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nonce, ciphertext := data[:nonceSize], data[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 "", fmt.Errorf("decrypt: %w", err)
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}
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return string(plaintext), nil
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}
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