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lib/pvault/cryptographic_operations.h

@@ -0,0 +1,52 @@
+#pragma once
+
+#include <Arduino.h>
+#include <SD.h>
+
+#include "pvault.h"
+
+#define CHUNK_SIZE 1024 // bytes
+
+namespace pvault_cryptography {
+    // generate values
+    bool generate_salt(uint8_t* salt);
+    bool generate_nonce(uint8_t* nonce);
+
+    // cryptography
+    bool derive_key(const String& password, const uint8_t* salt, uint8_t* key); // Derive key from password
+
+    bool decrypt_verify( // lightweight function to check if used key works with the ciphertext
+        const uint8_t* key,
+        const uint8_t* nonce,
+        File& file,
+        const uint32_t ciphertext_length,
+        const uint8_t* tag,
+        uint32_t header_size
+    );
+
+    bool encrypt_chunked( // writes ciphertext + tag to provided file
+        const uint8_t* key,
+        const uint8_t* nonce,
+        const uint8_t* plaintext,
+        uint32_t plaintext_length,
+        File& file
+    );
+
+    bool decrypt_chunked( // reads tag itself + plaintext to provided pointer
+        const uint8_t* key,
+        const uint8_t* nonce,
+        File& file,
+        uint32_t ciphertext_length,
+        uint8_t* plaintext
+    );
+
+    // vault file structure
+    bool write_header(File& file, const pvault::header& hdr);
+    bool read_header(File& file, pvault::header& hdr); // assumes that file pointer is set at the beginning of the file
+    
+    bool write_tag(File& file, const uint8_t* tag);
+    bool read_tag(File& file, uint8_t* tag); // assumes that file pointer is set on tag's location
+
+    // memory security
+    void secure_zero(void* ptr, uint32_t size);
+}