1 files changed, 97 insertions, 0 deletions
diff --git a/sys/dev/random/chacha20.c b/sys/dev/random/chacha20.c
new file mode 100644
index 0000000..41f823c
--- /dev/null
+++ b/sys/dev/random/chacha20.c
@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2023-2025 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <dev/random/chacha20.h>
+
+static const char sigma[16] = "expand 32-byte k";
+
+void chacha20_init(uint32_t state[16], const uint8_t key[32],
+    const uint8_t nonce[12], uint32_t counter)
+{
+    state[0] = ((uint32_t *)sigma)[0];
+    state[1] = ((uint32_t *)sigma)[1];
+    state[2] = ((uint32_t *)sigma)[2];
+    state[3] = ((uint32_t *)sigma)[3];
+
+    for (int i = 0; i < 8; ++i) {
+        state[4 + i] = ((uint32_t *)key)[i];
+    }
+
+    state[12] = counter;
+    state[13] = ((uint32_t *)nonce)[0];
+    state[14] = ((uint32_t *)nonce)[1];
+    state[15] = ((uint32_t *)nonce)[2];
+}
+
+void
+chacha20_block(uint32_t state[16], uint8_t out[64])
+{
+    uint32_t x[16];
+    memcpy(x, state, sizeof(x));
+
+    for (int i = 0; i < 10; i++) {
+
+        QR(x[0], x[4], x[8], x[12]);
+        QR(x[1], x[5], x[9], x[13]);
+        QR(x[2], x[6], x[10], x[14]);
+        QR(x[3], x[7], x[11], x[15]);
+
+        QR(x[0], x[5], x[10], x[15]);
+        QR(x[1], x[6], x[11], x[12]);
+        QR(x[2], x[7], x[8], x[13]);
+        QR(x[3], x[4], x[9], x[14]);
+    }
+
+    for (int i = 0; i < 16; ++i) {
+        x[i] += state[i];
+        ((uint32_t *)out)[i] = x[i];
+    }
+
+    state[12]++;
+}
+
+void
+chacha20_encrypt(uint32_t state[16], uint8_t *in,
+    uint8_t *out, size_t len)
+{
+    uint8_t block[64];
+    size_t offset = 0;
+
+    while (len > 0) {
+        chacha20_block(state, block);
+        size_t n = len > 64 ? 64 : len;
+
+        for (size_t i = 0; i < n; ++i) {
+            out[offset + i] = in ? in[offset + i] ^ block[i] : block[i];
+        }
+
+        offset += n;
+        len -= n;
+    }
+}