1 files changed, 87 insertions, 0 deletions
diff --git a/ext/ipcrypt/ipcrypt.c b/ext/ipcrypt/ipcrypt.c
new file mode 100644
index 0000000..6ef464a
--- /dev/null
+++ b/ext/ipcrypt/ipcrypt.c
@@ -0,0 +1,87 @@
+
+#include "ipcrypt.h"
+
+#define ROTL(X, R) (X) = (unsigned char) ((X) << (R)) | ((X) >> (8 - (R)))
+
+static void
+arx_fwd(unsigned char state[4])
+{
+    state[0] += state[1];
+    state[2] += state[3];
+    ROTL(state[1], 2);
+    ROTL(state[3], 5);
+    state[1] ^= state[0];
+    state[3] ^= state[2];
+    ROTL(state[0], 4);
+    state[0] += state[3];
+    state[2] += state[1];
+    ROTL(state[1], 3);
+    ROTL(state[3], 7);
+    state[1] ^= state[2];
+    state[3] ^= state[0];
+    ROTL(state[2], 4);
+}
+
+static void
+arx_bwd(unsigned char state[4])
+{
+    ROTL(state[2], 4);
+    state[1] ^= state[2];
+    state[3] ^= state[0];
+    ROTL(state[1], 5);
+    ROTL(state[3], 1);
+    state[0] -= state[3];
+    state[2] -= state[1];
+    ROTL(state[0], 4);
+    state[1] ^= state[0];
+    state[3] ^= state[2];
+    ROTL(state[1], 6);
+    ROTL(state[3], 3);
+    state[0] -= state[1];
+    state[2] -= state[3];
+}
+
+static inline void
+xor4(unsigned char *out, const unsigned char *x, const unsigned char *y)
+{
+    out[0] = x[0] ^ y[0];
+    out[1] = x[1] ^ y[1];
+    out[2] = x[2] ^ y[2];
+    out[3] = x[3] ^ y[3];
+}
+
+int
+ipcrypt_encrypt(unsigned char out[IPCRYPT_BYTES],
+                const unsigned char in[IPCRYPT_BYTES],
+                const unsigned char key[IPCRYPT_KEYBYTES])
+{
+    unsigned char state[4];
+
+    xor4(state, in, key);
+    arx_fwd(state);
+    xor4(state, state, key + 4);
+    arx_fwd(state);
+    xor4(state, state, key + 8);
+    arx_fwd(state);
+    xor4(out, state, key + 12);
+
+    return 0;
+}
+
+int
+ipcrypt_decrypt(unsigned char out[IPCRYPT_BYTES],
+                const unsigned char in[IPCRYPT_BYTES],
+                const unsigned char key[IPCRYPT_KEYBYTES])
+{
+    unsigned char state[4];
+
+    xor4(state, in, key + 12);
+    arx_bwd(state);
+    xor4(state, state, key + 8);
+    arx_bwd(state);
+    xor4(state, state, key + 4);
+    arx_bwd(state);
+    xor4(out, state, key);
+
+    return 0;
+}