/*
- * Copyright 2017 The OpenSSL Project Authors. All Rights Reserved.
+ * Copyright 2017-2019 The OpenSSL Project Authors. All Rights Reserved.
* Copyright 2015-2016 Cryptography Research, Inc.
*
* Licensed under the OpenSSL license (the "License"). You may not use
* Originally written by Mike Hamburg
*/
-#ifndef __DECAF_POINT_448_H__
-# define __DECAF_POINT_448_H__ 1
+#ifndef HEADER_POINT_448_H
+# define HEADER_POINT_448_H
# include "curve448utils.h"
# include "field.h"
-#ifdef __cplusplus
-extern "C" {
-#endif
+/* Comb config: number of combs, n, t, s. */
+#define COMBS_N 5
+#define COMBS_T 5
+#define COMBS_S 18
-# define DECAF_448_SCALAR_LIMBS ((446-1)/DECAF_WORD_BITS+1)
+/* Projective Niels coordinates */
+typedef struct {
+ gf a, b, c;
+} niels_s, niels_t[1];
+typedef struct {
+ niels_t n;
+ gf z;
+} pniels_t[1];
-/* The number of bits in a scalar */
-# define DECAF_448_SCALAR_BITS 446
+/* Precomputed base */
+struct curve448_precomputed_s {
+ niels_t table[COMBS_N << (COMBS_T - 1)];
+};
-/* Number of bytes in a serialized point. */
-# define DECAF_448_SER_BYTES 56
+# define C448_SCALAR_LIMBS ((446-1)/C448_WORD_BITS+1)
-/*
- * Number of bytes in an elligated point. For now set the same as SER_BYTES
- * but could be different for other curves.
- */
-# define DECAF_448_HASH_BYTES 56
+/* The number of bits in a scalar */
+# define C448_SCALAR_BITS 446
/* Number of bytes in a serialized scalar. */
-# define DECAF_448_SCALAR_BYTES 56
-
-/* Number of bits in the "which" field of an elligator inverse */
-# define DECAF_448_INVERT_ELLIGATOR_WHICH_BITS 3
-
-/* The cofactor the curve would have, if we hadn't removed it */
-# define DECAF_448_REMOVED_COFACTOR 4
+# define C448_SCALAR_BYTES 56
/* X448 encoding ratio. */
-# define DECAF_X448_ENCODE_RATIO 2
+# define X448_ENCODE_RATIO 2
/* Number of bytes in an x448 public key */
-# define DECAF_X448_PUBLIC_BYTES 56
+# define X448_PUBLIC_BYTES 56
/* Number of bytes in an x448 private key */
-# define DECAF_X448_PRIVATE_BYTES 56
+# define X448_PRIVATE_BYTES 56
/* Twisted Edwards extended homogeneous coordinates */
typedef struct curve448_point_s {
- gf_448_t x, y, z, t;
+ gf x, y, z, t;
} curve448_point_t[1];
/* Precomputed table based on a point. Can be trivial implementation. */
/* Scalar is stored packed, because we don't need the speed. */
typedef struct curve448_scalar_s {
- decaf_word_t limb[DECAF_448_SCALAR_LIMBS];
+ c448_word_t limb[C448_SCALAR_LIMBS];
} curve448_scalar_t[1];
/* A scalar equal to 1. */
/* The identity point on the curve. */
extern const curve448_point_t curve448_point_identity;
-/* An arbitrarily chosen base point on the curve. */
-extern const curve448_point_t curve448_point_base;
-
/* Precomputed table for the base point on the curve. */
extern const struct curve448_precomputed_s *curve448_precomputed_base;
+extern const niels_t *curve448_wnaf_base;
/*
* Read a scalar from wire format or from bytes.
* out (out): Deserialized form.
*
* Returns:
- * DECAF_SUCCESS: The scalar was correctly encoded.
- * DECAF_FAILURE: The scalar was greater than the modulus, and has been reduced
+ * C448_SUCCESS: The scalar was correctly encoded.
+ * C448_FAILURE: The scalar was greater than the modulus, and has been reduced
* modulo that modulus.
*/
-__owur decaf_error_t curve448_scalar_decode(
- curve448_scalar_t out,
- const unsigned char ser[DECAF_448_SCALAR_BYTES]);
+c448_error_t curve448_scalar_decode(curve448_scalar_t out,
+ const unsigned char ser[C448_SCALAR_BYTES]);
/*
* Read a scalar from wire format or from bytes. Reduces mod scalar prime.
* ser (out): Serialized form of a scalar.
* s (in): Deserialized scalar.
*/
-void curve448_scalar_encode(unsigned char ser[DECAF_448_SCALAR_BYTES],
+void curve448_scalar_encode(unsigned char ser[C448_SCALAR_BYTES],
const curve448_scalar_t s);
/*
- * Add two scalars. The scalars may use the same memory.
- *
+ * Add two scalars. |a|, |b| and |out| may alias each other.
+ *
* a (in): One scalar.
* b (in): Another scalar.
* out (out): a+b.
const curve448_scalar_t a, const curve448_scalar_t b);
/*
- * Subtract two scalars. The scalars may use the same memory.
+ * Subtract two scalars. |a|, |b| and |out| may alias each other.
* a (in): One scalar.
* b (in): Another scalar.
* out (out): a-b.
const curve448_scalar_t a, const curve448_scalar_t b);
/*
- * Multiply two scalars. The scalars may use the same memory.
- *
+ * Multiply two scalars. |a|, |b| and |out| may alias each other.
+ *
* a (in): One scalar.
* b (in): Another scalar.
* out (out): a*b.
const curve448_scalar_t a, const curve448_scalar_t b);
/*
-* Halve a scalar. The scalars may use the same memory.
-*
+* Halve a scalar. |a| and |out| may alias each other.
+*
* a (in): A scalar.
* out (out): a/2.
*/
void curve448_scalar_halve(curve448_scalar_t out, const curve448_scalar_t a);
/*
- * Copy a scalar. The scalars may use the same memory, in which case this
+ * Copy a scalar. The scalars may alias each other, in which case this
* function does nothing.
- *
+ *
* a (in): A scalar.
* out (out): Will become a copy of a.
*/
}
/*
- * Test whether two points are equal. If yes, return DECAF_TRUE, else return
- * DECAF_FALSE.
+ * Test whether two points are equal. If yes, return C448_TRUE, else return
+ * C448_FALSE.
*
* a (in): A point.
* b (in): Another point.
- *
+ *
* Returns:
- * DECAF_TRUE: The points are equal.
- * DECAF_FALSE: The points are not equal.
+ * C448_TRUE: The points are equal.
+ * C448_FALSE: The points are not equal.
*/
-__owur decaf_bool_t curve448_point_eq(const curve448_point_t a,
- const curve448_point_t b);
+__owur c448_bool_t curve448_point_eq(const curve448_point_t a,
+ const curve448_point_t b);
/*
* Double a point. Equivalent to curve448_point_add(two_a,a,a), but potentially
* scalar (in): The scalar to multiply by.
*
* Returns:
- * DECAF_SUCCESS: The scalarmul succeeded.
- * DECAF_FAILURE: The scalarmul didn't succeed, because the base point is in a
+ * C448_SUCCESS: The scalarmul succeeded.
+ * C448_FAILURE: The scalarmul didn't succeed, because the base point is in a
* small subgroup.
*/
-__owur decaf_error_t decaf_x448(uint8_t out[DECAF_X448_PUBLIC_BYTES],
- const uint8_t base[DECAF_X448_PUBLIC_BYTES],
- const uint8_t scalar[DECAF_X448_PRIVATE_BYTES]);
+__owur c448_error_t x448_int(uint8_t out[X448_PUBLIC_BYTES],
+ const uint8_t base[X448_PUBLIC_BYTES],
+ const uint8_t scalar[X448_PRIVATE_BYTES]);
/*
- * Multiply a point by DECAF_X448_ENCODE_RATIO, then encode it like RFC 7748.
+ * Multiply a point by X448_ENCODE_RATIO, then encode it like RFC 7748.
*
* This function is mainly used internally, but is exported in case
* it will be useful.
*
* The ratio is necessary because the internal representation doesn't
* track the cofactor information, so on output we must clear the cofactor.
- * This would multiply by the cofactor, but in fact internally libdecaf's
- * points are always even, so it multiplies by half the cofactor instead.
+ * This would multiply by the cofactor, but in fact internally points are always
+ * even, so it multiplies by half the cofactor instead.
*
* As it happens, this aligns with the base point definitions; that is,
* if you pass the Decaf/Ristretto base point to this function, the result
- * will be DECAF_X448_ENCODE_RATIO times the X448
+ * will be X448_ENCODE_RATIO times the X448
* base point.
*
* out (out): The scaled and encoded point.
* p (in): The point to be scaled and encoded.
*/
void curve448_point_mul_by_ratio_and_encode_like_x448(
- uint8_t out[DECAF_X448_PUBLIC_BYTES],
+ uint8_t out[X448_PUBLIC_BYTES],
const curve448_point_t p);
-/* The base point for X448 Diffie-Hellman */
-extern const uint8_t decaf_x448_base_point[DECAF_X448_PUBLIC_BYTES];
-
/*
* RFC 7748 Diffie-Hellman base point scalarmul. This function uses a different
* (non-Decaf) encoding.
- *
+ *
* out (out): The scaled point base*scalar
* scalar (in): The scalar to multiply by.
*/
-void decaf_x448_derive_public_key(
- uint8_t out[DECAF_X448_PUBLIC_BYTES],
- const uint8_t scalar[DECAF_X448_PRIVATE_BYTES]);
+void x448_derive_public_key(uint8_t out[X448_PUBLIC_BYTES],
+ const uint8_t scalar[X448_PRIVATE_BYTES]);
/*
* Multiply a precomputed base point by a scalar: out = scalar*base.
* base2 (in): A second point to be scaled.
* scalar2 (in) A second scalar to multiply by.
*
- * Warning: This function takes variable time, and may leak the scalars used.
+ * Warning: This function takes variable time, and may leak the scalars used.
* It is designed for signature verification.
*/
void curve448_base_double_scalarmul_non_secret(curve448_point_t combo,
* to_test (in): The point to test.
*
* Returns:
- * DECAF_TRUE The point is valid.
- * DECAF_FALSE The point is invalid.
+ * C448_TRUE The point is valid.
+ * C448_FALSE The point is invalid.
*/
-__owur decaf_bool_t curve448_point_valid(const curve448_point_t to_test);
+__owur c448_bool_t curve448_point_valid(const curve448_point_t to_test);
/* Overwrite scalar with zeros. */
void curve448_scalar_destroy(curve448_scalar_t scalar);
/* Overwrite point with zeros. */
void curve448_point_destroy(curve448_point_t point);
-#ifdef __cplusplus
-} /* extern "C" */
-#endif
-
-#endif /* __DECAF_POINT_448_H__ */
+#endif /* HEADER_POINT_448_H */
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