Implement the ChaCha family of stream ciphers.

CREDITS

@@ -12,3 +12,8 @@ The Cryb libraries include code written by Dag-Erling Smørgrav for the
 University of Oslo.  The University of Oslo has graciously granted the
 Cryb.to project permission to reuse this code under the 3-clause New
 BSD License.
+
+The Cryb libraries include test vectors generated by Joachim
+Strömbergson and published under the 2-clause Simplified BSD License.
+Joachim Strömbergson has graciously granted the Cryb.to project
+permission to reuse this code under the 3-clause New BSD License.

include/cryb/chacha.h

@@ -0,0 +1,66 @@
+/*-
+ * Copyright (c) 2017 Dag-Erling Smørgrav
+ * 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. The name of the author may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
+ */
+
+#ifndef CRYB_CHACHA_H_INCLUDED
+#define CRYB_CHACHA_H_INCLUDED
+
+#ifndef CRYB_TO
+#include <cryb/to.h>
+#endif
+
+#include <cryb/cipher.h>
+
+CRYB_BEGIN
+
+#define chacha_cipher			cryb_chacha_cipher
+#define chacha_ctx			cryb_chacha_ctx
+#define chacha_init			cryb_chacha_init
+#define chacha_reset			cryb_chacha_reset
+#define chacha_keystream		cryb_chacha_keystream
+#define chacha_encrypt			cryb_chacha_encrypt
+#define chacha_decrypt			cryb_chacha_decrypt
+#define chacha_finish			cryb_chacha_finish
+
+extern cipher_algorithm chacha_cipher;
+
+typedef struct {
+	uint32_t state[16];
+	unsigned int rounds;
+} chacha_ctx;
+
+void chacha_init(chacha_ctx *, cipher_mode, const uint8_t *, size_t);
+void chacha_reset(chacha_ctx *, const uint8_t *, unsigned int);
+size_t chacha_keystream(chacha_ctx *, uint8_t *, size_t);
+size_t chacha_encrypt(chacha_ctx *, const void *, uint8_t *, size_t);
+size_t chacha_decrypt(chacha_ctx *, const uint8_t *, void *, size_t);
+void chacha_finish(chacha_ctx *);
+
+CRYB_END
+
+#endif

lib/cipher/Makefile.am

@@ -4,6 +4,7 @@ lib_LTLIBRARIES = libcryb-cipher.la
 
 libcryb_cipher_la_SOURCES = \
 	cryb_aes.c \
+	cryb_chacha.c \
 	cryb_rc4.c \
 	\
 	cryb_cipher.c

lib/cipher/cryb_chacha.c

@@ -0,0 +1,188 @@
+/*-
+ * Copyright (c) 2017 Dag-Erling Smørgrav
+ * 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. The name of the author may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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 "cryb/impl.h"
+
+#include <stdint.h>
+#include <string.h>
+
+#include <cryb/bitwise.h>
+#include <cryb/endian.h>
+#include <cryb/memset_s.h>
+
+#include <cryb/chacha.h>
+
+#define CHACHA_QR(x, a, b, c, d)					\
+	do {								\
+		x[a] = x[a] + x[b]; x[d] = rol32(x[d] ^ x[a], 16);	\
+		x[c] = x[c] + x[d]; x[b] = rol32(x[b] ^ x[c], 12);	\
+		x[a] = x[a] + x[b]; x[d] = rol32(x[d] ^ x[a],  8);	\
+		x[c] = x[c] + x[d]; x[b] = rol32(x[b] ^ x[c],  7);	\
+	} while (0)
+
+static const char magic128[] = "expand 16-byte k";
+static const char magic256[] = "expand 32-byte k";
+
+/*
+ * Fill the state array with 16 bytes of magic and 32 bytes of key,
+ * repeating the key if necessary.  The 8-byte stream position and the
+ * 8-byte nonce are initialized to all-zeroes.  The number of rounds is
+ * set to 20, the most commonly used value.
+ */
+void
+chacha_init(chacha_ctx *ctx, cipher_mode mode, const uint8_t *key, size_t keylen)
+{
+
+	(void)mode;
+	memset(ctx, 0, sizeof *ctx);
+	if (keylen == 32) {
+		/* magic */
+		ctx->state[ 0] = le32dec(magic256 + 0);
+		ctx->state[ 1] = le32dec(magic256 + 4);
+		ctx->state[ 2] = le32dec(magic256 + 8);
+		ctx->state[ 3] = le32dec(magic256 + 12);
+		/* first half of key */
+		ctx->state[ 4] = le32dec(key + 0);
+		ctx->state[ 5] = le32dec(key + 4);
+		ctx->state[ 6] = le32dec(key + 8);
+		ctx->state[ 7] = le32dec(key + 12);
+		/* second half of key */
+		ctx->state[ 8] = le32dec(key + 16);
+		ctx->state[ 9] = le32dec(key + 20);
+		ctx->state[10] = le32dec(key + 24);
+		ctx->state[11] = le32dec(key + 28);
+	} else {
+		/* magic */
+		ctx->state[ 0] = le32dec(magic128 + 0);
+		ctx->state[ 1] = le32dec(magic128 + 4);
+		ctx->state[ 2] = le32dec(magic128 + 8);
+		ctx->state[ 3] = le32dec(magic128 + 12);
+		/* first half of key */
+		ctx->state[ 4] = le32dec(key + 0);
+		ctx->state[ 5] = le32dec(key + 4);
+		ctx->state[ 6] = le32dec(key + 8);
+		ctx->state[ 7] = le32dec(key + 12);
+		/* repeat first half of key */
+		ctx->state[ 8] = le32dec(key + 0);
+		ctx->state[ 9] = le32dec(key + 4);
+		ctx->state[10] = le32dec(key + 8);
+		ctx->state[11] = le32dec(key + 12);
+	}
+	ctx->rounds = 20;
+}
+
+/*
+ * Reset the stream position, load a new nonce, and change the number of
+ * rounds if requested.
+ */
+void
+chacha_reset(chacha_ctx *ctx, const uint8_t *nonce, unsigned int rounds)
+{
+
+	/* reset stream counter */
+	ctx->state[12] = 0;
+	ctx->state[13] = 0;
+	/* copy nonce */
+	ctx->state[14] = le32dec(nonce + 0);
+	ctx->state[15] = le32dec(nonce + 4);
+	/* set rounds if specified */
+	if (rounds != 0)
+		ctx->rounds = rounds;
+}
+
+/*
+ * Generate a block of keystream.
+ */
+size_t
+chacha_keystream(chacha_ctx *ctx, uint8_t *ks, size_t len)
+{
+
+	return (chacha_encrypt(ctx, NULL, ks, len));
+}
+
+/*
+ * Encryption: generate a block of keystream, xor it with the plaintext to
+ * produce the ciphertext, and increment the stream position.
+ */
+size_t
+chacha_encrypt(chacha_ctx *ctx, const void *vpt, uint8_t *ct, size_t len)
+{
+	const uint8_t *pt = vpt;
+	uint64_t ctr;
+	uint32_t mix[16];
+	uint8_t ks[64];
+	unsigned int b, i;
+
+	len -= len % sizeof ks;
+	for (b = 0; b < len; b += sizeof ks) {
+		memcpy(mix, ctx->state, sizeof mix);
+		for (i = 0; i < ctx->rounds; i += 2) {
+			CHACHA_QR(mix,  0,  4,  8, 12);
+			CHACHA_QR(mix,  1,  5,  9, 13);
+			CHACHA_QR(mix,  2,  6, 10, 14);
+			CHACHA_QR(mix,  3,  7, 11, 15);
+			CHACHA_QR(mix,  0,  5, 10, 15);
+			CHACHA_QR(mix,  1,  6, 11, 12);
+			CHACHA_QR(mix,  2,  7,  8, 13);
+			CHACHA_QR(mix,  3,  4,  9, 14);
+		}
+		for (i = 0; i < 16; ++i)
+			le32enc(ks + i * 4, ctx->state[i] + mix[i]);
+		if (pt == NULL) {
+			memcpy(ct, ks, sizeof ks);
+			ct += sizeof ks;
+		} else {
+			for (i = 0; i < 64 && i < len; ++i)
+				*ct++ = *pt++ ^ ks[i];
+		}
+		ctr = le64dec(ctx->state + 12);
+		le64enc(ctx->state + 12, ++ctr);
+	}
+	return (len);
+}
+
+/*
+ * Decryption: identical to encryption.
+ */
+size_t
+chacha_decrypt(chacha_ctx *ctx, const uint8_t *ct, void *vpt, size_t len)
+{
+
+	return (chacha_encrypt(ctx, ct, vpt, len));
+}
+
+/*
+ * Wipe our state.
+ */
+void
+chacha_finish(chacha_ctx *ctx)
+{
+
+	(void)memset_s(ctx, 0, sizeof *ctx, sizeof *ctx);
+}

t/.gitignore

@@ -1,6 +1,7 @@
 /t_adler
 /t_aes
 /t_assert
+/t_chacha
 /t_cipher
 /t_core
 /t_ctype

t/Makefile.am

@@ -79,8 +79,9 @@ endif CRYB_RAND
 if CRYB_CIPHER
 TESTS += t_cipher
 t_cipher_LDADD = $(libt) $(libcipher)
-TESTS += t_aes t_rc4
+TESTS += t_aes t_chacha t_rc4
 t_aes_LDADD = $(libt) $(libcipher)
+t_chacha_LDADD = $(libt) $(libcipher)
 t_rc4_LDADD = $(libt) $(libcipher)
 endif CRYB_CIPHER