From 20cb29c2f8c5c87bc590896854a20b1473ceb358 Mon Sep 17 00:00:00 2001
From: "info@mode42.com" <info@mode42.com>
Date: Sat, 8 Aug 2026 03:54:55 +0000
Subject: #2

---
 src/core/crypto_libsodium.c | 111 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 111 insertions(+)
 create mode 100644 src/core/crypto_libsodium.c

(limited to 'src/core/crypto_libsodium.c')

diff --git a/src/core/crypto_libsodium.c b/src/core/crypto_libsodium.c
new file mode 100644
index 0000000..85cf537
--- /dev/null
+++ b/src/core/crypto_libsodium.c
@@ -0,0 +1,111 @@
+#include "hybbx/types.h"
+
+#include <sodium.h>
+
+#include <stdlib.h>
+#include <string.h>
+
+static int sodium_ready;
+
+static int ensure_sodium(void)
+{
+    if (!sodium_ready) {
+        if (sodium_init() < 0) {
+            return -1;
+        }
+        sodium_ready = 1;
+    }
+
+    return 0;
+}
+
+void hybbx_libsodium_chacha_lock(uint8_t *ciphertext, uint8_t tag[16],
+                                 const uint8_t key[32], const uint8_t nonce[24],
+                                 const uint8_t *aad, size_t aad_len,
+                                 const uint8_t *plaintext, size_t plaintext_len)
+{
+    unsigned long long out_len = 0;
+    uint8_t *packed;
+    size_t packed_cap;
+
+    if (ensure_sodium() != 0) {
+        return;
+    }
+
+    packed_cap = plaintext_len +
+                 crypto_aead_xchacha20poly1305_ietf_ABYTES;
+    packed = malloc(packed_cap);
+    if (packed == NULL) {
+        return;
+    }
+
+    if (crypto_aead_xchacha20poly1305_ietf_encrypt(
+            packed, &out_len, plaintext, plaintext_len, aad, aad_len, NULL,
+            nonce, key) != 0) {
+        free(packed);
+        return;
+    }
+
+    if (plaintext_len > 0 && ciphertext != NULL) {
+        memcpy(ciphertext, packed, plaintext_len);
+    }
+    memcpy(tag, packed + plaintext_len,
+           crypto_aead_xchacha20poly1305_ietf_ABYTES);
+    free(packed);
+}
+
+int hybbx_libsodium_chacha_unlock(uint8_t *plaintext, const uint8_t tag[16],
+                                  const uint8_t key[32], const uint8_t nonce[24],
+                                  const uint8_t *aad, size_t aad_len,
+                                  const uint8_t *ciphertext, size_t ciphertext_len)
+{
+    unsigned long long pt_len = 0;
+    uint8_t *packed;
+    size_t packed_len;
+    int rc;
+
+    if (ensure_sodium() != 0) {
+        return -1;
+    }
+
+    packed_len = ciphertext_len +
+                 crypto_aead_xchacha20poly1305_ietf_ABYTES;
+    packed = malloc(packed_len);
+    if (packed == NULL) {
+        return -1;
+    }
+
+    if (ciphertext_len > 0 && ciphertext != NULL) {
+        memcpy(packed, ciphertext, ciphertext_len);
+    }
+    memcpy(packed + ciphertext_len, tag,
+           crypto_aead_xchacha20poly1305_ietf_ABYTES);
+
+    rc = crypto_aead_xchacha20poly1305_ietf_decrypt(
+        plaintext, &pt_len, NULL, packed, packed_len, aad, aad_len, nonce,
+        key);
+
+    free(packed);
+    return rc;
+}
+
+void hybbx_libsodium_x25519_public_key(uint8_t public_key[32],
+                                         const uint8_t secret_key[32])
+{
+    if (ensure_sodium() != 0) {
+        return;
+    }
+
+    crypto_scalarmult_base(public_key, secret_key);
+}
+
+void hybbx_libsodium_x25519_shared(uint8_t shared[32],
+                                   const uint8_t secret_key[32],
+                                   const uint8_t peer_public_key[32])
+{
+    if (ensure_sodium() != 0) {
+        return;
+    }
+
+    crypto_scalarmult(shared, secret_key, peer_public_key);
+}
-- 
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