Implement XChaCha20 and XChaCha20-Poly1305

README

@@ -33,13 +33,13 @@ Ciphers
 -------
 
 - [x] ChaCha20
-- [ ] XChaCha20
+- [x] XChaCha20
 
 AEAD
 ----
 
 - [x] ChaCha20-Poly1305
-- [ ] XChaCha20-Poly1305
+- [x] XChaCha20-Poly1305
 
 ECC
 ---

aead_chacha20_poly1305.c

@@ -180,14 +180,174 @@ chacha20_poly1305_open(const uint8_t *key, size_t keylen, const uint8_t *iv,
 	return 1;
 }
 
+static int
+xchacha20_poly1305_seal(const uint8_t *key, size_t keylen, const uint8_t *iv,
+    size_t ivlen, uint8_t *out, size_t *outlen, const uint8_t *aad,
+    size_t aadlen, const uint8_t *in, size_t inlen)
+{
+	struct chacha20_ctx	cctx;
+	struct poly1305_ctx	pctx;
+	uint8_t			poly1305_key[LC_POLY1305_KEYLEN];
+	uint8_t			buf[sizeof(uint64_t) * 2];
+	size_t			i, olen;
+
+	if (inlen > UINT64_MAX || aadlen > UINT64_MAX ||
+	    inlen > SIZE_MAX - LC_POLY1305_TAGLEN ||
+	    inlen > SIZE_MAX - CHACHA20_CHUNK + 1 ||
+	    (inlen + CHACHA20_CHUNK - 1) / CHACHA20_CHUNK >
+	    CHACHA20_CTRMAX - 1) {
+		if (out == NULL)
+			*outlen = 0;
+		return 0;
+	}
+
+	if (out == NULL) {
+		*outlen = inlen + LC_POLY1305_TAGLEN;
+		return 1;
+	}
+
+	*outlen = 0;
+
+	for (i = 0; i < LC_POLY1305_KEYLEN; i++)
+		poly1305_key[i] = 0;
+	if (!xchacha20_common_init(&cctx, key, keylen, iv, ivlen) ||
+	    !chacha20_common_update(&cctx, poly1305_key, &olen, poly1305_key,
+	    LC_POLY1305_KEYLEN))
+		return 0;
+	if (!chacha20_common_final(&cctx, poly1305_key + olen, &olen))
+		return 0;
+
+	if (!poly1305_init(&pctx, poly1305_key, LC_POLY1305_KEYLEN) ||
+	    !poly1305_update(&pctx, aad, aadlen))
+		return 0;
+	if (aadlen % 16 != 0)
+		if (!poly1305_update(&pctx, zeropad, 16 - (aadlen % 16)))
+			return 0;
+
+	if (!xchacha20_common_init_from(&cctx, key, keylen, iv, ivlen, 1))
+		return 0;
+	if (!chacha20_common_update(&cctx, out, &olen, in, inlen))
+		return 0;
+	*outlen = olen;
+	if (!chacha20_common_final(&cctx, out + olen, &olen))
+		return 0;
+	if (!poly1305_update(&pctx, out, inlen))
+		return 0;
+	if (inlen % 16 != 0)
+		if (!poly1305_update(&pctx, zeropad, 16 - (inlen % 16)))
+			return 0;
+
+	store64le(&buf[0], aadlen);
+	store64le(&buf[sizeof(uint64_t)], inlen);
+	if (!poly1305_update(&pctx, buf, sizeof(buf)) ||
+	    !poly1305_final(&pctx, out + inlen, &olen))
+		return 0;
+
+	lc_scrub(buf, sizeof(buf));
+	lc_scrub(poly1305_key, sizeof(poly1305_key));
+
+	*outlen = inlen + LC_POLY1305_TAGLEN;
+
+	return 1;
+}
+
+static int
+xchacha20_poly1305_open(const uint8_t *key, size_t keylen, const uint8_t *iv,
+    size_t ivlen, uint8_t *out, size_t *outlen, const uint8_t *aad,
+    size_t aadlen, const uint8_t *in, size_t inlen)
+{
+	const uint8_t		*tagp;
+	struct chacha20_ctx	 cctx;
+	struct poly1305_ctx	 pctx;
+	uint8_t			 poly1305_key[LC_POLY1305_KEYLEN];
+	uint8_t			 tag[LC_POLY1305_TAGLEN];
+	uint8_t			 buf[sizeof(uint64_t) * 2];
+	size_t			 i, olen, ctlen;
+
+	if (inlen < LC_POLY1305_TAGLEN ||
+	    inlen > UINT64_MAX || aadlen > UINT64_MAX ||
+	    inlen > SIZE_MAX - LC_POLY1305_TAGLEN ||
+	    inlen > SIZE_MAX - CHACHA20_CHUNK + 1 ||
+	    (inlen + CHACHA20_CHUNK - 1) / CHACHA20_CHUNK >
+	    CHACHA20_CTRMAX - 1) {
+		if (out == NULL)
+			*outlen = 0;
+		return 0;
+	}
+
+	if (out == NULL) {
+		*outlen = inlen - LC_POLY1305_TAGLEN;
+		return 1;
+	}
+
+	*outlen = 0;
+	ctlen = inlen - LC_POLY1305_TAGLEN;
+	tagp = in + ctlen;
+
+	for (i = 0; i < LC_POLY1305_KEYLEN; i++)
+		poly1305_key[i] = 0;
+	if (!xchacha20_common_init(&cctx, key, keylen, iv, ivlen) ||
+	    !chacha20_common_update(&cctx, poly1305_key, &olen, poly1305_key,
+	    LC_POLY1305_KEYLEN))
+		return 0;
+	if (!chacha20_common_final(&cctx, poly1305_key + olen, &olen))
+		return 0;
+
+	if (!poly1305_init(&pctx, poly1305_key, LC_POLY1305_KEYLEN) ||
+	    !poly1305_update(&pctx, aad, aadlen))
+		return 0;
+	if (aadlen % 16 != 0)
+		if (!poly1305_update(&pctx, zeropad, 16 - (aadlen % 16)))
+			return 0;
+
+	if (!poly1305_update(&pctx, in, ctlen))
+		return 0;
+	if (ctlen % 16 != 0)
+		if (!poly1305_update(&pctx, zeropad, 16 - (ctlen % 16)))
+			return 0;
+
+	store64le(&buf[0], aadlen);
+	store64le(&buf[sizeof(uint64_t)], ctlen);
+	if (!poly1305_update(&pctx, buf, sizeof(buf)) ||
+	    !poly1305_final(&pctx, tag, &olen))
+		return 0;
+
+	if (!lc_ct_cmp(tag, tagp, LC_POLY1305_TAGLEN))
+		return 0;
+
+	lc_scrub(buf, sizeof(buf));
+	lc_scrub(poly1305_key, sizeof(poly1305_key));
+
+	if (!xchacha20_common_init_from(&cctx, key, keylen, iv, ivlen, 1))
+		return 0;
+	if (!chacha20_common_update(&cctx, out, &olen, in, ctlen))
+		return 0;
+	*outlen = olen;
+	if (!chacha20_common_final(&cctx, out + olen, &olen))
+		return 0;
+	*outlen += olen;
+
+	return 1;
+}
+
 
 static struct lc_aead_impl	chacha20_poly1305_impl = {
 	.seal = &chacha20_poly1305_seal,
 	.open = &chacha20_poly1305_open,
 };
 
+static struct lc_aead_impl	xchacha20_poly1305_impl = {
+	.seal = &xchacha20_poly1305_seal,
+	.open = &xchacha20_poly1305_open,
+};
+
 const struct lc_aead_impl *
 lc_aead_impl_chacha20_poly1305(void)
 {
 	return &chacha20_poly1305_impl;
 }
+const struct lc_aead_impl *
+lc_aead_impl_xchacha20_poly1305(void)
+{
+	return &xchacha20_poly1305_impl;
+}

cipher_chacha20.c

@@ -54,6 +54,49 @@ chacha20_common_init(void *arg, const uint8_t *key, size_t keylen,
 	return chacha20_common_init_from(arg, key, keylen, iv, ivlen, 0);
 }
 
+int
+xchacha20_common_init_from(void *arg, const uint8_t *key, size_t keylen,
+    const uint8_t *iv, size_t ivlen, uint64_t counter)
+{
+	struct chacha20_ctx	*ctx = arg;
+	size_t			 i;
+
+	if (keylen != LC_XCHACHA20_KEYLEN || ivlen != LC_XCHACHA20_IVLEN)
+		return 0;
+
+	for (i = 0; i < CHACHA20_CHUNK_WORDS; i++)
+		ctx->s[i] = 0;
+	for (i = 0; i < CHACHA20_KEY_WORDS; i++)
+		ctx->k[i] = load32le(&key[i * 4]);
+	for (i = 0; i < CHACHA20_NONCE_WORDS; i++)
+		ctx->n[i] = load32le(&iv[i * 4]);
+	ctx->mlen = 0;
+
+	hchacha20_block(ctx);
+
+	ctx->k[0] = ctx->s[0];
+	ctx->k[1] = ctx->s[1];
+	ctx->k[2] = ctx->s[2];
+	ctx->k[3] = ctx->s[3];
+	ctx->k[4] = ctx->s[12];
+	ctx->k[5] = ctx->s[13];
+	ctx->k[6] = ctx->s[14];
+	ctx->k[7] = ctx->s[15];
+	ctx->n[0] = counter;
+	ctx->n[1] = counter >> 32;
+	ctx->n[2] = load32le(&iv[16]);
+	ctx->n[3] = load32le(&iv[20]);
+
+	return 1;
+}
+
+int
+xchacha20_common_init(void *arg, const uint8_t *key, size_t keylen,
+    const uint8_t *iv, size_t ivlen)
+{
+	return xchacha20_common_init_from(arg, key, keylen, iv, ivlen, 0);
+}
+
 int
 chacha20_common_update(void *arg, uint8_t *out, size_t *outlen,
     const uint8_t *in, size_t inlen)
@@ -201,8 +244,29 @@ static struct lc_cipher_impl	chacha20_impl = {
 	.ctx_free = NULL,
 };
 
+static struct lc_cipher_impl	xchacha20_impl = {
+	.encrypt_init = &xchacha20_common_init,
+	.encrypt_update = &chacha20_common_update,
+	.encrypt_final = &chacha20_common_final,
+	.encrypt = &chacha20_common,
+
+	.decrypt_init = &xchacha20_common_init,
+	.decrypt_update = &chacha20_common_update,
+	.decrypt_final = &chacha20_common_final,
+	.decrypt = &chacha20_common,
+
+	.ctx_new = &chacha20_ctx_new,
+	.ctx_free = NULL,
+};
+
 const struct lc_cipher_impl *
 lc_cipher_impl_chacha20(void)
 {
 	return &chacha20_impl;
 }
+
+const struct lc_cipher_impl *
+lc_cipher_impl_xchacha20(void)
+{
+	return &xchacha20_impl;
+}

cipher_chacha20.h

@@ -22,6 +22,10 @@ int	chacha20_common_init_from(void *, const uint8_t *, size_t,
 	    const uint8_t *, size_t, uint32_t);
 int	chacha20_common_init(void *, const uint8_t *, size_t, const uint8_t *,
 	    size_t);
+int	xchacha20_common_init_from(void *, const uint8_t *, size_t,
+	    const uint8_t *, size_t, uint64_t);
+int	xchacha20_common_init(void *, const uint8_t *, size_t, const uint8_t *,
+	    size_t);
 int	chacha20_common_update(void *, uint8_t *, size_t *, const uint8_t *,
 	    size_t);
 int	chacha20_common_final(void *, uint8_t *, size_t *);

impl_chacha20.c

@@ -83,3 +83,42 @@ chacha20_block(struct chacha20_ctx *ctx)
 	for (i = 0; i < CHACHA20_CHUNK_WORDS; i++)
 		ctx->s[i] += x[i];
 }
+
+void
+hchacha20_block(struct chacha20_ctx *ctx)
+{
+	uint32_t	x[CHACHA20_CHUNK_WORDS];
+	size_t		i;
+
+	x[0] = SIGMA0;
+	x[1] = SIGMA1;
+	x[2] = SIGMA2;
+	x[3] = SIGMA3;
+	x[4] = ctx->k[0];
+	x[5] = ctx->k[1];
+	x[6] = ctx->k[2];
+	x[7] = ctx->k[3];
+	x[8] = ctx->k[4];
+	x[9] = ctx->k[5];
+	x[10] = ctx->k[6];
+	x[11] = ctx->k[7];
+	x[12] = ctx->n[0];
+	x[13] = ctx->n[1];
+	x[14] = ctx->n[2];
+	x[15] = ctx->n[3];
+
+	for (i = 0; i < CHACHA20_ROUNDS; i++) {
+		QUARTERROUND(x[0], x[4], x[8], x[12]);
+		QUARTERROUND(x[1], x[5], x[9], x[13]);
+		QUARTERROUND(x[2], x[6], x[10], x[14]);
+		QUARTERROUND(x[3], x[7], x[11], x[15]);
+
+		QUARTERROUND(x[0], x[5], x[10], x[15]);
+		QUARTERROUND(x[1], x[6], x[11], x[12]);
+		QUARTERROUND(x[2], x[7], x[8], x[13]);
+		QUARTERROUND(x[3], x[4], x[9], x[14]);
+	}
+
+	for (i = 0; i < CHACHA20_CHUNK_WORDS; i++)
+		ctx->s[i] = x[i];
+}

impl_chacha20.h

@@ -38,3 +38,4 @@ struct chacha20_ctx {
 
 
 void	chacha20_block(struct chacha20_ctx *);
+void	hchacha20_block(struct chacha20_ctx *);

lilcrypto.h

@@ -34,6 +34,8 @@
 /* Ciphers. */
 #define LC_CHACHA20_KEYLEN	32
 #define LC_CHACHA20_IVLEN	12
+#define LC_XCHACHA20_KEYLEN	32
+#define LC_XCHACHA20_IVLEN	24
 
 
 /*
@@ -115,6 +117,7 @@ struct lc_cipher_ctx	*lc_cipher_ctx_new(const struct lc_cipher_impl *);
 void			 lc_cipher_ctx_free(struct lc_cipher_ctx *);
 
 const struct lc_cipher_impl	*lc_cipher_impl_chacha20(void);
+const struct lc_cipher_impl	*lc_cipher_impl_xchacha20(void);
 
 
 /*
@@ -132,6 +135,7 @@ int	lc_aead_open(const struct lc_aead_impl *, const uint8_t *, size_t,
     const uint8_t *, size_t);
 
 const struct lc_aead_impl	*lc_aead_impl_chacha20_poly1305(void);
+const struct lc_aead_impl	*lc_aead_impl_xchacha20_poly1305(void);
 
 
 /*

wycheproof/Makefile

@@ -22,7 +22,9 @@ tests-aead:
 .for p in ${AEAD}
 	perl ${.CURDIR}/aead.pl ${TESTOPTS} -x ./${p} \
 	    ${WYCHEPROOF_DIR}/testvectors/chacha20_poly1305_test.json \
-	    ${WYCHEPROOF_DIR}/testvectors_v1/chacha20_poly1305_test.json
+	    ${WYCHEPROOF_DIR}/testvectors_v1/chacha20_poly1305_test.json \
+	    ${WYCHEPROOF_DIR}/testvectors/xchacha20_poly1305_test.json \
+	    ${WYCHEPROOF_DIR}/testvectors_v1/xchacha20_poly1305_test.json
 .endfor
 
 tests-mac:

wycheproof_aead.c

@@ -79,6 +79,7 @@ kw2impl(const char *s)
 {
 	static const struct kwimpl	tbl[] = {
 		{ "CHACHA20-POLY1305", &lc_aead_impl_chacha20_poly1305 },
+		{ "XCHACHA20-POLY1305", &lc_aead_impl_xchacha20_poly1305 },
 	};
 	struct kwimpl	*match;