X-Git-Url: https://www.bearssl.org/gitweb//home/git/?p=BearSSL;a=blobdiff_plain;f=src%2Fsymcipher%2Fchacha20_ct.c;fp=src%2Fsymcipher%2Fchacha20_ct.c;h=9961eb119f217eb818ee137e29d4dffbc82d1d25;hp=0000000000000000000000000000000000000000;hb=b42bd5972f935ffc32019acac6f8a07ae08ae9c2;hpb=9e71c0673a9f46f82e43125919619f296698292e

diff --git a/src/symcipher/chacha20_ct.c b/src/symcipher/chacha20_ct.c
new file mode 100644
index 0000000..9961eb1
--- /dev/null
+++ b/src/symcipher/chacha20_ct.c
@@ -0,0 +1,106 @@
+/*
+ * Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining 
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be 
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include "inner.h"
+
+/* see bearssl_block.h */
+uint32_t
+br_chacha20_ct_run(const void *key,
+	const void *iv, uint32_t cc, void *data, size_t len)
+{
+	unsigned char *buf;
+	uint32_t kw[8], ivw[3];
+	size_t u;
+
+	static const uint32_t CW[] = {
+		0x61707865, 0x3320646e, 0x79622d32, 0x6b206574
+	};
+
+	buf = data;
+	for (u = 0; u < 8; u ++) {
+		kw[u] = br_dec32le((const unsigned char *)key + (u << 2));
+	}
+	for (u = 0; u < 3; u ++) {
+		ivw[u] = br_dec32le((const unsigned char *)iv + (u << 2));
+	}
+	while (len > 0) {
+		uint32_t state[16];
+		int i;
+		size_t clen;
+		unsigned char tmp[64];
+
+		memcpy(&state[0], CW, sizeof CW);
+		memcpy(&state[4], kw, sizeof kw);
+		state[12] = cc;
+		memcpy(&state[13], ivw, sizeof ivw);
+		for (i = 0; i < 10; i ++) {
+
+#define QROUND(a, b, c, d)   do { \
+		state[a] += state[b]; \
+		state[d] ^= state[a]; \
+		state[d] = (state[d] << 16) | (state[d] >> 16); \
+		state[c] += state[d]; \
+		state[b] ^= state[c]; \
+		state[b] = (state[b] << 12) | (state[b] >> 20); \
+		state[a] += state[b]; \
+		state[d] ^= state[a]; \
+		state[d] = (state[d] <<  8) | (state[d] >> 24); \
+		state[c] += state[d]; \
+		state[b] ^= state[c]; \
+		state[b] = (state[b] <<  7) | (state[b] >> 25); \
+	} while (0)
+
+			QROUND( 0,  4,  8, 12);
+			QROUND( 1,  5,  9, 13);
+			QROUND( 2,  6, 10, 14);
+			QROUND( 3,  7, 11, 15);
+			QROUND( 0,  5, 10, 15);
+			QROUND( 1,  6, 11, 12);
+			QROUND( 2,  7,  8, 13);
+			QROUND( 3,  4,  9, 14);
+
+#undef QROUND
+
+		}
+		for (u = 0; u < 4; u ++) {
+			br_enc32le(&tmp[u << 2], state[u] + CW[u]);
+		}
+		for (u = 4; u < 12; u ++) {
+			br_enc32le(&tmp[u << 2], state[u] + kw[u - 4]);
+		}
+		br_enc32le(&tmp[48], state[12] + cc);
+		for (u = 13; u < 16; u ++) {
+			br_enc32le(&tmp[u << 2], state[u] + ivw[u - 13]);
+		}
+
+		clen = len < 64 ? len : 64;
+		for (u = 0; u < clen; u ++) {
+			buf[u] ^= tmp[u];
+		}
+		buf += clen;
+		len -= clen;
+		cc ++;
+	}
+	return cc;
+}