aesni: Implement a AES-NI based CTR crypter using the key schedule

src/libstrongswan/plugins/aesni/aesni_ctr.c

@@ -0,0 +1,223 @@
+/*
+ * Copyright (C) 2015 Martin Willi
+ * Copyright (C) 2015 revosec AG
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+#include "aesni_ctr.h"
+#include "aesni_key.h"
+
+#include <tmmintrin.h>
+
+typedef struct private_aesni_ctr_t private_aesni_ctr_t;
+
+/**
+ * CTR en/decryption method type
+ */
+typedef void (*aesni_ctr_fn_t)(private_aesni_ctr_t*, size_t, u_char*, u_char*);
+
+/**
+ * Private data of an aesni_ctr_t object.
+ */
+struct private_aesni_ctr_t {
+
+	/**
+	 * Public aesni_ctr_t interface.
+	 */
+	aesni_ctr_t public;
+
+	/**
+	 * Key size
+	 */
+	u_int key_size;
+
+	/**
+	 * Key schedule
+	 */
+	aesni_key_t *key;
+
+	/**
+	 * Encryption method
+	 */
+	aesni_ctr_fn_t crypt;
+
+	/**
+	 * Counter state
+	 */
+	struct {
+		char nonce[4];
+		char iv[8];
+		u_int32_t counter;
+	} __attribute__((packed, aligned(sizeof(__m128i)))) state;
+};
+
+/**
+ * Generic CTR encryption
+ */
+static void encrypt_ctr(private_aesni_ctr_t *this,
+						size_t len, u_char *in, u_char *out)
+{
+	__m128i state, t, d, b, swap, one, *bi, *bo;
+	u_int i, round, blocks, rem;
+
+	one = _mm_set_epi32(0, 0, 0, 1);
+	swap = _mm_setr_epi8(15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0);
+	state = _mm_load_si128((__m128i*)&this->state);
+	blocks = len / AES_BLOCK_SIZE;
+	rem = len % AES_BLOCK_SIZE;
+	bi = (__m128i*)in;
+	bo = (__m128i*)out;
+
+	for (i = 0; i < blocks; i++)
+	{
+		d = _mm_loadu_si128(bi + i);
+		t = _mm_xor_si128(state, this->key->schedule[0]);
+		for (round = 1; round < this->key->rounds; round++)
+		{
+			t = _mm_aesenc_si128(t, this->key->schedule[round]);
+		}
+		t = _mm_aesenclast_si128(t, this->key->schedule[this->key->rounds]);
+		t = _mm_xor_si128(t, d);
+		_mm_storeu_si128(bo + i, t);
+
+		/* big endian increment */
+		t = _mm_shuffle_epi8(state, swap);
+		t = _mm_add_epi64(t, one);
+		state = _mm_shuffle_epi8(t, swap);
+	}
+
+	if (rem)
+	{
+		memset(&b, 0, sizeof(b));
+		memcpy(&b, bi + blocks, rem);
+
+		d = _mm_loadu_si128(&b);
+		t = _mm_xor_si128(state, this->key->schedule[0]);
+		for (round = 1; round < this->key->rounds; round++)
+		{
+			t = _mm_aesenc_si128(t, this->key->schedule[round]);
+		}
+		t = _mm_aesenclast_si128(t, this->key->schedule[this->key->rounds]);
+		t = _mm_xor_si128(t, d);
+		_mm_storeu_si128(&b, t);
+
+		memcpy(bo + blocks, &b, rem);
+	}
+}
+
+METHOD(crypter_t, crypt, bool,
+	private_aesni_ctr_t *this, chunk_t in, chunk_t iv, chunk_t *out)
+{
+	u_char *buf;
+
+	if (!this->key || iv.len != sizeof(this->state.iv))
+	{
+		return FALSE;
+	}
+	memcpy(this->state.iv, iv.ptr, sizeof(this->state.iv));
+	this->state.counter = htonl(1);
+
+	buf = in.ptr;
+	if (out)
+	{
+		*out = chunk_alloc(in.len);
+		buf = out->ptr;
+	}
+	this->crypt(this, in.len, in.ptr, buf);
+	return TRUE;
+}
+
+METHOD(crypter_t, get_block_size, size_t,
+	private_aesni_ctr_t *this)
+{
+	return 1;
+}
+
+METHOD(crypter_t, get_iv_size, size_t,
+	private_aesni_ctr_t *this)
+{
+	return sizeof(this->state.iv);
+}
+
+METHOD(crypter_t, get_key_size, size_t,
+	private_aesni_ctr_t *this)
+{
+	return this->key_size + sizeof(this->state.nonce);
+}
+
+METHOD(crypter_t, set_key, bool,
+	private_aesni_ctr_t *this, chunk_t key)
+{
+	if (key.len != get_key_size(this))
+	{
+		return FALSE;
+	}
+
+	memcpy(this->state.nonce, key.ptr + key.len - sizeof(this->state.nonce),
+		   sizeof(this->state.nonce));
+	key.len -= sizeof(this->state.nonce);
+
+	DESTROY_IF(this->key);
+	this->key = aesni_key_create(TRUE, key);
+
+	return this->key;
+}
+
+METHOD(crypter_t, destroy, void,
+	private_aesni_ctr_t *this)
+{
+	DESTROY_IF(this->key);
+	free(this);
+}
+
+/**
+ * See header
+ */
+aesni_ctr_t *aesni_ctr_create(encryption_algorithm_t algo, size_t key_size)
+{
+	private_aesni_ctr_t *this;
+
+	if (algo != ENCR_AES_CTR)
+	{
+		return NULL;
+	}
+	switch (key_size)
+	{
+		case 0:
+			key_size = 16;
+			break;
+		case 16:
+		case 24:
+		case 32:
+			break;
+		default:
+			return NULL;
+	}
+
+	INIT(this,
+		.public = {
+			.crypter = {
+				.encrypt = _crypt,
+				.decrypt = _crypt,
+				.get_block_size = _get_block_size,
+				.get_iv_size = _get_iv_size,
+				.get_key_size = _get_key_size,
+				.set_key = _set_key,
+				.destroy = _destroy,
+			},
+		},
+		.key_size = key_size,
+		.crypt = encrypt_ctr,
+	);
+
+	return &this->public;
+}