xts128.c: initial draft.

crypto/modes/xts128.c

+/* ====================================================================
+ * Copyright (c) 2011 The OpenSSL Project.  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. All advertising materials mentioning features or use of this
+ *    software must display the following acknowledgment:
+ *    "This product includes software developed by the OpenSSL Project
+ *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
+ *
+ * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
+ *    endorse or promote products derived from this software without
+ *    prior written permission. For written permission, please contact
+ *    openssl-core@openssl.org.
+ *
+ * 5. Products derived from this software may not be called "OpenSSL"
+ *    nor may "OpenSSL" appear in their names without prior written
+ *    permission of the OpenSSL Project.
+ *
+ * 6. Redistributions of any form whatsoever must retain the following
+ *    acknowledgment:
+ *    "This product includes software developed by the OpenSSL Project
+ *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
+ * EXPRESSED 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 OpenSSL PROJECT OR
+ * ITS 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 <openssl/crypto.h>
+#include "modes_lcl.h"
+#include <string.h>
+
+#ifndef MODES_DEBUG
+# ifndef NDEBUG
+#  define NDEBUG
+# endif
+#endif
+#include <assert.h>
+
+typedef struct {
+	void      *key1, *key2;
+	block128_f block1,block2;
+} XTS128_CONTEXT;
+
+int CRYPTO_xts128_encrypt(const XTS128_CONTEXT *ctx, u64 secno,
+	const unsigned char *inp, unsigned char *out,
+	size_t len, int enc)
+{
+	const union { long one; char little; } is_endian = {1};
+	union { u64 u[2]; u32 d[4]; u8 c[16]; } tweak, scratch;
+
+	if (len<16) return -1;
+
+	if (is_endian.little) {
+		tweak.u[0] = secno;
+		tweak.u[1] = 0;
+	}
+	else {
+		PUTU32(tweak.c,secno);
+		PUTU32(tweak.c+4,secno>>32);
+		tweak.u[1] = 0;
+	}
+
+	(*ctx->block2)(tweak.c,tweak.c,ctx->key2);
+
+	if (!enc && len%16) len-=16;
+
+	while (len>=16) {
+#if defined(STRICT_ALIGNMENT)
+		memcpy(scratch.c,inp,16);
+		scratch.u[0] ^= tweak.u[0];
+		scratch.u[1] ^= tweak.u[1];
+#else
+		scratch.u[0] = ((u64*)inp)[0]^tweak.u[0];
+		scratch.u[1] = ((u64*)inp)[1]^tweak.u[1];
+#endif
+		(*ctx->block1)(scratch.c,scratch.c,ctx->key1);
+		scratch.u[0] ^= tweak.u[0];
+		scratch.u[1] ^= tweak.u[1];
+		memcpy(out,scratch.c,16);
+		inp += 16;
+		out += 16;
+		len -= 16;
+
+		if (is_endian.little) {
+			unsigned int carry,res;
+			
+			res = 0x87&(((int)tweak.d[3])>>31);
+			carry = tweak.u[0]>>63;
+			tweak.u[0] = (tweak.u[0]<<1)^res;
+			tweak.u[1] = (tweak.u[1]<<1)|carry;
+		}
+		else {
+			unsigned int carry,c,i;
+
+			for (carry=0,i=0;i<16;++i) {
+				c = tweak.c[i];
+				tweak.c[i] = (c<<1)|carry;
+				carry = c>>7;
+			}
+			tweak.c[0] ^= 0x87&(0-carry);
+		}
+	}
+	if (len) {
+		unsigned int i;
+
+		if (enc) {
+			for (i=0;i<len;++i) {
+				u8 c = inp[i];
+				out[i] = scratch.c[i];
+				scratch.c[i] = c;
+			}
+			scratch.u[0] ^= tweak.u[0];
+			scratch.u[1] ^= tweak.u[1];
+			(*ctx->block1)(scratch.c,scratch.c,ctx->key1);
+			scratch.u[0] ^= tweak.u[0];
+			scratch.u[1] ^= tweak.u[1];
+			memcpy(out-16,scratch.c,16);
+		}
+		else {
+			union { u64 u[2]; u8 c[16]; } tweak1;
+
+			if (is_endian.little) {
+				unsigned int carry,res;
+	
+				res = 0x87&(((int)tweak.d[3])>>31);
+				carry = tweak.u[0]>>63;
+				tweak1.u[0] = (tweak.u[0]<<1)^res;
+				tweak1.u[1] = (tweak.u[1]<<1)|carry;
+			}
+			else {
+				unsigned int carry,c;
+
+				for (carry=0,i=0;i<16;++i) {
+					c = tweak.c[i];
+					tweak1.c[i] = (c<<1)|carry;
+					carry = c>>7;
+				}
+				tweak1.c[0] ^= 0x87&(0-carry);
+			}
+#if defined(STRICT_ALIGNMENT)
+			memcpy(scratch.c,inp,16);
+			scratch.u[0] ^= tweak1.u[0];
+			scratch.u[1] ^= tweak1.u[1];
+#else
+			scratch.u[0] = ((u64*)inp)[0]^tweak1.u[0];
+			scratch.u[1] = ((u64*)inp)[1]^tweak1.u[1];
+#endif
+			(*ctx->block1)(scratch.c,scratch.c,ctx->key1);
+			scratch.u[0] ^= tweak1.u[0];
+			scratch.u[1] ^= tweak1.u[1];
+
+			for (i=0;i<len;++i) {
+				u8 c = inp[16+i];
+				out[16+i] = scratch.c[i];
+				scratch.c[i] = c;
+			}
+			scratch.u[0] ^= tweak.u[0];
+			scratch.u[1] ^= tweak.u[1];
+			(*ctx->block1)(scratch.c,scratch.c,ctx->key1);
+			scratch.u[0] ^= tweak.u[0];
+			scratch.u[1] ^= tweak.u[1];
+			memcpy (out,scratch.c,16);
+		}
+	}
+
+	return 0;
+}