1 files changed, 120 insertions, 0 deletions
diff --git a/src/Crypto/chachaRng.c b/src/Crypto/chachaRng.c
new file mode 100644
index 00000000..b3d92039
--- /dev/null
+++ b/src/Crypto/chachaRng.c
@@ -0,0 +1,120 @@
+/*	$OpenBSD: arc4random.c,v 1.54 2015/09/13 08:31:47 guenther Exp $	*/
+
+/*
+ * Copyright (c) 1996, David Mazieres <dm@uun.org>
+ * Copyright (c) 2008, Damien Miller <djm@openbsd.org>
+ * Copyright (c) 2013, Markus Friedl <markus@openbsd.org>
+ * Copyright (c) 2014, Theo de Raadt <deraadt@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * ChaCha based random number generator for OpenBSD.
+ */
+
+/*
+ * Adapted for VeraCrypt
+ */
+
+#include "chachaRng.h"
+#include "cpu.h"
+#include "misc.h"
+#include <string.h>
+
+static VC_INLINE void ChaCha20RngReKey (ChaCha20RngCtx* pCtx, int useCallBack)
+{
+	/* fill rs_buf with the keystream */
+	if (pCtx->m_rs_have)
+		memset(pCtx->m_rs_buf + sizeof(pCtx->m_rs_buf) - pCtx->m_rs_have, 0, pCtx->m_rs_have);
+	ChaCha256Encrypt(&pCtx->m_chachaCtx, pCtx->m_rs_buf, sizeof (pCtx->m_rs_buf),
+	    pCtx->m_rs_buf);
+	/* mix in optional user provided data */
+	if (pCtx->m_getRandSeedCallback && useCallBack) {
+		unsigned char dat[CHACHA20RNG_KEYSZ + CHACHA20RNG_IVSZ];
+		size_t i;
+
+		pCtx->m_getRandSeedCallback (dat, sizeof (dat));
+
+		for (i = 0; i < (CHACHA20RNG_KEYSZ + CHACHA20RNG_IVSZ); i++)
+			pCtx->m_rs_buf[i] ^= dat[i];
+
+		burn (dat, sizeof(dat));
+	}
+
+	/* immediately reinit for backtracking resistance */
+	ChaCha256Init (&pCtx->m_chachaCtx, pCtx->m_rs_buf, pCtx->m_rs_buf + CHACHA20RNG_KEYSZ, 20);
+	memset(pCtx->m_rs_buf, 0, CHACHA20RNG_KEYSZ + CHACHA20RNG_IVSZ);
+	pCtx->m_rs_have = sizeof (pCtx->m_rs_buf) - CHACHA20RNG_KEYSZ - CHACHA20RNG_IVSZ;
+}
+
+static VC_INLINE void ChaCha20RngStir(ChaCha20RngCtx* pCtx)
+{
+	ChaCha20RngReKey (pCtx, 1);
+
+	/* invalidate rs_buf */
+	pCtx->m_rs_have = 0;
+	memset(pCtx->m_rs_buf, 0, CHACHA20RNG_RSBUFSZ);
+
+	pCtx->m_rs_count = 1600000;
+}
+
+static VC_INLINE void ChaCha20RngStirIfNeeded(ChaCha20RngCtx* pCtx, size_t len)
+{
+	if (pCtx->m_rs_count <= len) {
+		ChaCha20RngStir(pCtx);
+	} else
+		pCtx->m_rs_count -= len;
+}
+
+void ChaCha20RngInit (ChaCha20RngCtx* pCtx, const unsigned char* key, GetRandSeedFn rngSeedCallback, size_t InitialBytesToSkip)
+{
+	ChaCha256Init (&pCtx->m_chachaCtx, key, key + 32, 20);
+	pCtx->m_getRandSeedCallback = rngSeedCallback;
+
+	/* fill rs_buf with the keystream */
+	pCtx->m_rs_have = 0;
+	memset (pCtx->m_rs_buf, 0, sizeof (pCtx->m_rs_buf));
+	pCtx->m_rs_count = 1600000;
+
+	ChaCha20RngReKey(pCtx, 0);	
+
+	if (InitialBytesToSkip)
+		ChaCha20RngGetBytes (pCtx, NULL, InitialBytesToSkip);
+}
+
+void ChaCha20RngGetBytes (ChaCha20RngCtx* pCtx, unsigned char* buffer, size_t bufferLen)
+{
+	unsigned char *buf = (unsigned char*) buffer;
+	unsigned char* keystream;
+	size_t m;
+
+	ChaCha20RngStirIfNeeded(pCtx, bufferLen);
+
+	while (bufferLen > 0) {
+		if (pCtx->m_rs_have > 0) {
+			m = VC_MIN(bufferLen, pCtx->m_rs_have);
+			keystream = pCtx->m_rs_buf + sizeof(pCtx->m_rs_buf) - pCtx->m_rs_have;
+			if (buf)
+			{
+				memcpy(buf, keystream, m);
+				buf += m;
+			}
+			memset(keystream, 0, m);
+			bufferLen -= m;
+			pCtx->m_rs_have -= m;
+		}
+		if (pCtx->m_rs_have == 0)
+			ChaCha20RngReKey (pCtx, 0);
+	}
+}