cli/packages/pam/session/encryption.go

package session

import (
	"crypto/aes"
	"crypto/cipher"
	"crypto/hmac"
	"crypto/rand"
	"crypto/sha256"
	"encoding/base64"
	"fmt"
	"io"
)

func DecryptData(encryptedData []byte, keyBase64 string) ([]byte, error) {
	key, err := base64.StdEncoding.DecodeString(keyBase64)
	if err != nil {
		return nil, fmt.Errorf("failed to decode encryption key: %w", err)
	}

	// Create AES cipher
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil, fmt.Errorf("failed to create AES cipher: %w", err)
	}

	// Create GCM mode
	gcm, err := cipher.NewGCM(block)
	if err != nil {
		return nil, fmt.Errorf("failed to create GCM: %w", err)
	}

	// Extract nonce and ciphertext
	nonceSize := gcm.NonceSize()
	if len(encryptedData) < nonceSize {
		return nil, fmt.Errorf("encrypted data too short")
	}

	nonce := encryptedData[:nonceSize]
	ciphertext := encryptedData[nonceSize:]

	// Decrypt the data
	plaintext, err := gcm.Open(nil, nonce, ciphertext, nil)
	if err != nil {
		return nil, fmt.Errorf("failed to decrypt data: %w", err)
	}

	return plaintext, nil
}

func EncryptData(data []byte, keyBase64 string) ([]byte, error) {
	// Decode the base64 key
	key, err := base64.StdEncoding.DecodeString(keyBase64)
	if err != nil {
		return nil, fmt.Errorf("failed to decode encryption key: %w", err)
	}

	// Create AES cipher
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil, fmt.Errorf("failed to create AES cipher: %w", err)
	}

	// Create GCM mode
	gcm, err := cipher.NewGCM(block)
	if err != nil {
		return nil, fmt.Errorf("failed to create GCM: %w", err)
	}

	// Generate random nonce
	nonce := make([]byte, gcm.NonceSize())
	if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
		return nil, fmt.Errorf("failed to generate nonce: %w", err)
	}

	// Encrypt the data
	ciphertext := gcm.Seal(nonce, nonce, data, nil)
	return ciphertext, nil
}

func GenerateNonce() (string, error) {
	nonce := make([]byte, 18)
	_, err := rand.Read(nonce)
	if err != nil {
		return "", fmt.Errorf("failed to generate nonce: %w", err)
	}

	return base64.StdEncoding.EncodeToString(nonce), nil
}

func HmacSHA256(key, data []byte) []byte {
	h := hmac.New(sha256.New, key)
	h.Write(data)
	return h.Sum(nil)
}

func SHA256Hash(data []byte) []byte {
	h := sha256.New()
	h.Write(data)
	return h.Sum(nil)
}