feat(backup): Add backup/restore to the server

api/crypto/aes.go

@@ -0,0 +1,70 @@
+package crypto
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"io"
+
+	"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
+
+var emptySalt []byte = make([]byte, 0, 0)
+
+// AesEncrypt reads from input, encrypts with AES-256 and writes to the 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)
+	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 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.
+func AesDecrypt(input io.Reader, passphrase []byte) (io.Reader, 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)
+	if err != nil {
+		return nil, err
+	}
+
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, 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[:])
+
+	reader := &cipher.StreamReader{S: stream, R: input}
+
+	return reader, nil
+}