fix(backups): improved archive encryption [EE-6764] (#11489)

api/crypto/aes.go

@@ -1,52 +1,216 @@
 package crypto
 
 import (
+	"bufio"
+	"bytes"
 	"crypto/aes"
 	"crypto/cipher"
+	"crypto/rand"
+	"errors"
+	"fmt"
 	"io"
 
+	"golang.org/x/crypto/argon2"
 	"golang.org/x/crypto/scrypt"
 )
 
-// NOTE: has to go with what is considered to be a simplistic in that it omits any
-// authentication of the encrypted data.
-// Person with better knowledge is welcomed to improve it.
-// sourced from https://golang.org/src/crypto/cipher/example_test.go
+const (
+	// AES GCM settings
+	aesGcmHeader    = "AES256-GCM" // The encrypted file header
+	aesGcmBlockSize = 1024 * 1024  // 1MB block for aes gcm
 
-var emptySalt []byte = make([]byte, 0)
+	// Argon2 settings
+	// Recommded settings lower memory hardware according to current OWASP recommendations
+	// Considering some people run portainer on a NAS I think it's prudent not to assume we're on server grade hardware
+	// https://cheatsheetseries.owasp.org/cheatsheets/Password_Storage_Cheat_Sheet.html#argon2id
+	argon2MemoryCost = 12 * 1024
+	argon2TimeCost   = 3
+	argon2Threads    = 1
+	argon2KeyLength  = 32
+)
 
-// AesEncrypt reads from input, encrypts with AES-256 and writes to the output.
-// passphrase is used to generate an encryption key.
+// AesEncrypt reads from input, encrypts with AES-256 and writes to output. passphrase is used to generate an encryption key
 func AesEncrypt(input io.Reader, output io.Writer, passphrase []byte) error {
-	// making a 32 bytes key that would correspond to AES-256
-	// don't necessarily need a salt, so just kept in empty
-	key, err := scrypt.Key(passphrase, emptySalt, 32768, 8, 1, 32)
+	err := aesEncryptGCM(input, output, passphrase)
 	if err != nil {
-		return err
-	}
-
-	block, err := aes.NewCipher(key)
-	if err != nil {
-		return err
-	}
-
-	// If the key is unique for each ciphertext, then it's ok to use a zero
-	// IV.
-	var iv [aes.BlockSize]byte
-	stream := cipher.NewOFB(block, iv[:])
-
-	writer := &cipher.StreamWriter{S: stream, W: output}
-	// Copy the input to the output, encrypting as we go.
-	if _, err := io.Copy(writer, input); err != nil {
-		return err
+		return fmt.Errorf("error encrypting file: %w", err)
 	}
 
 	return nil
 }
 
-// AesDecrypt reads from input, decrypts with AES-256 and returns the reader to a read decrypted content from.
-// passphrase is used to generate an encryption key.
+// AesDecrypt reads from input, decrypts with AES-256 and returns the reader to read the decrypted content from
 func AesDecrypt(input io.Reader, passphrase []byte) (io.Reader, error) {
+	// Read file header to determine how it was encrypted
+	inputReader := bufio.NewReader(input)
+	header, err := inputReader.Peek(len(aesGcmHeader))
+	if err != nil {
+		return nil, fmt.Errorf("error reading encrypted backup file header: %w", err)
+	}
+
+	if string(header) == aesGcmHeader {
+		reader, err := aesDecryptGCM(inputReader, passphrase)
+		if err != nil {
+			return nil, fmt.Errorf("error decrypting file: %w", err)
+		}
+
+		return reader, nil
+	}
+
+	// Use the previous decryption routine which has no header (to support older archives)
+	reader, err := aesDecryptOFB(inputReader, passphrase)
+	if err != nil {
+		return nil, fmt.Errorf("error decrypting legacy file backup: %w", err)
+	}
+
+	return reader, nil
+}
+
+// aesEncryptGCM reads from input, encrypts with AES-256 and writes to output. passphrase is used to generate an encryption key.
+func aesEncryptGCM(input io.Reader, output io.Writer, passphrase []byte) error {
+	// Derive key using argon2 with a random salt
+	salt := make([]byte, 16) // 16 bytes salt
+	if _, err := io.ReadFull(rand.Reader, salt); err != nil {
+		return err
+	}
+
+	key := argon2.IDKey(passphrase, salt, argon2TimeCost, argon2MemoryCost, argon2Threads, 32)
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return err
+	}
+
+	aesgcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return err
+	}
+
+	// Generate nonce
+	nonce, err := NewRandomNonce(aesgcm.NonceSize())
+	if err != nil {
+		return err
+	}
+
+	// write the header
+	if _, err := output.Write([]byte(aesGcmHeader)); err != nil {
+		return err
+	}
+
+	// Write nonce and salt to the output file
+	if _, err := output.Write(salt); err != nil {
+		return err
+	}
+	if _, err := output.Write(nonce.Value()); err != nil {
+		return err
+	}
+
+	// Buffer for reading plaintext blocks
+	buf := make([]byte, aesGcmBlockSize) // Adjust buffer size as needed
+	ciphertext := make([]byte, len(buf)+aesgcm.Overhead())
+
+	// Encrypt plaintext in blocks
+	for {
+		n, err := io.ReadFull(input, buf)
+		if n == 0 {
+			break // end of plaintext input
+		}
+
+		if err != nil && !(errors.Is(err, io.EOF) || errors.Is(err, io.ErrUnexpectedEOF)) {
+			return err
+		}
+
+		// Seal encrypts the plaintext using the nonce returning the updated slice.
+		ciphertext = aesgcm.Seal(ciphertext[:0], nonce.Value(), buf[:n], nil)
+
+		_, err = output.Write(ciphertext)
+		if err != nil {
+			return err
+		}
+
+		nonce.Increment()
+	}
+
+	return nil
+}
+
+// aesDecryptGCM reads from input, decrypts with AES-256 and returns the reader to read the decrypted content from.
+func aesDecryptGCM(input io.Reader, passphrase []byte) (io.Reader, error) {
+	// Reader & verify header
+	header := make([]byte, len(aesGcmHeader))
+	if _, err := io.ReadFull(input, header); err != nil {
+		return nil, err
+	}
+
+	if string(header) != aesGcmHeader {
+		return nil, fmt.Errorf("invalid header")
+	}
+
+	// Read salt
+	salt := make([]byte, 16) // Salt size
+	if _, err := io.ReadFull(input, salt); err != nil {
+		return nil, err
+	}
+
+	key := argon2.IDKey(passphrase, salt, argon2TimeCost, argon2MemoryCost, argon2Threads, 32)
+
+	// Initialize AES cipher block
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	// Create GCM mode with the cipher block
+	aesgcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return nil, err
+	}
+
+	// Read nonce from the input reader
+	nonce := NewNonce(aesgcm.NonceSize())
+	if err := nonce.Read(input); err != nil {
+		return nil, err
+	}
+
+	// Initialize a buffer to store decrypted data
+	buf := bytes.Buffer{}
+	plaintext := make([]byte, aesGcmBlockSize)
+
+	// Decrypt the ciphertext in blocks
+	for {
+		// Read a block of ciphertext from the input reader
+		ciphertextBlock := make([]byte, aesGcmBlockSize+aesgcm.Overhead()) // Adjust block size as needed
+		n, err := io.ReadFull(input, ciphertextBlock)
+		if n == 0 {
+			break // end of ciphertext
+		}
+
+		if err != nil && !(errors.Is(err, io.EOF) || errors.Is(err, io.ErrUnexpectedEOF)) {
+			return nil, err
+		}
+
+		// Decrypt the block of ciphertext
+		plaintext, err = aesgcm.Open(plaintext[:0], nonce.Value(), ciphertextBlock[:n], nil)
+		if err != nil {
+			return nil, err
+		}
+
+		_, err = buf.Write(plaintext)
+		if err != nil {
+			return nil, err
+		}
+
+		nonce.Increment()
+	}
+
+	return &buf, nil
+}
+
+// aesDecryptOFB reads from input, decrypts with AES-256 and returns the reader to a read decrypted content from.
+// passphrase is used to generate an encryption key.
+// note: This function used to decrypt files that were encrypted without a header i.e. old archives
+func aesDecryptOFB(input io.Reader, passphrase []byte) (io.Reader, error) {
+	var emptySalt []byte = make([]byte, 0)
+
 	// making a 32 bytes key that would correspond to AES-256
 	// don't necessarily need a salt, so just kept in empty
 	key, err := scrypt.Key(passphrase, emptySalt, 32768, 8, 1, 32)
@@ -59,11 +223,9 @@ func AesDecrypt(input io.Reader, passphrase []byte) (io.Reader, error) {
 		return nil, err
 	}
 
-	// If the key is unique for each ciphertext, then it's ok to use a zero
-	// IV.
+	// If the key is unique for each ciphertext, then it's ok to use a zero IV.
 	var iv [aes.BlockSize]byte
 	stream := cipher.NewOFB(block, iv[:])
-
 	reader := &cipher.StreamReader{S: stream, R: input}
 
 	return reader, nil