X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=crypto%2Flibeddsa%2Flib%2Ffld.h;fp=crypto%2Flibeddsa%2Flib%2Ffld.h;h=598c6b2bb3af22ce2521393d479ae1d82baaa904;hb=7bfbc0423ba40ea5156e06c8fb62bacd5ea93390;hp=0000000000000000000000000000000000000000;hpb=2ae349f5ed63b026cff763b35984dd36b330870a;p=zpackage

diff --git a/crypto/libeddsa/lib/fld.h b/crypto/libeddsa/lib/fld.h
new file mode 100644
index 0000000..598c6b2
--- /dev/null
+++ b/crypto/libeddsa/lib/fld.h
@@ -0,0 +1,144 @@
+#ifndef FLD_H
+#define FLD_H
+
+#include <stdint.h>
+
+#include "bitness.h"
+#include "compat.h"
+#include "limb.h"
+
+
+#ifdef USE_64BIT
+
+/*
+ * in 64bit mode we use 5 limbs each 51 bits long
+ */
+
+#define FLD_LIMB_NUM		5
+#define FLD_LIMB_BITS		51
+
+#define FLD_LIMB_MASK		((1L << FLD_LIMB_BITS)-1)
+
+#else
+
+/*
+ * in 32bit mode fld_t consists of 10 limbs alternating in size
+ * between 26 and 25 bits.
+ * this approach is inspired from djb's curve25519-paper, where it
+ * is explained in more detail.
+ */
+
+#define FLD_LIMB_NUM		10
+
+/* macros for alternating limb sizes: use with d=1,0,1,0,... */
+#define FLD_LIMB_BITS(d)	(25+(d))
+#define FLD_LIMB_MASK(d)	((1 << FLD_LIMB_BITS(d))-1)
+
+#endif
+
+
+/*
+ * fld_t is our datatype for all operations modulo 2^255-19.
+ *
+ * since we typedef an array here, all parameters of type fld_t get
+ * a call-by-reference semantic!
+ */
+
+typedef limb_t fld_t[FLD_LIMB_NUM];
+
+
+
+/*
+ * exported constants
+ */
+extern const fld_t con_d;
+extern const fld_t con_2d;
+extern const fld_t con_m2d;
+extern const fld_t con_j;
+
+
+/*
+ * prototypes for 32bit/64bit specific functions 
+ */
+void	fld_reduce(fld_t dst, const fld_t x);
+void	fld_import(fld_t dst, const uint8_t src[32]);
+void	fld_export(uint8_t dst[32], const fld_t src);
+void	fld_mul(fld_t res, const fld_t a, const fld_t b);
+void	fld_scale(fld_t dst, const fld_t src, limb_t x);
+void	fld_sq(fld_t res, const fld_t a);
+
+
+/*
+ * prototypes for common code
+ */
+int	fld_eq(const fld_t a, const fld_t b);
+void	fld_inv(fld_t res, const fld_t z);
+void	fld_pow2523(fld_t res, const fld_t z);
+
+
+
+/*
+ * simple inline functions
+ */
+
+static INLINE void
+fld_set0(fld_t res, limb_t x0)
+{
+	int i;
+	res[0] = x0;
+	for (i = 1; i < FLD_LIMB_NUM; i++)
+		res[i] = 0;
+}
+
+
+static INLINE void
+fld_add(fld_t res, const fld_t a, const fld_t b)
+{
+	int i;
+	for (i = 0; i < FLD_LIMB_NUM; i++)
+		res[i] = a[i] + b[i];
+}
+
+static INLINE void
+fld_sub(fld_t res, const fld_t a, const fld_t b)
+{
+	int i;
+	for (i = 0; i < FLD_LIMB_NUM; i++)
+		res[i] = a[i] - b[i];
+}
+
+/*
+ * fld_tinyscale scales an element a without reducing it. this could
+ * be used for conditionally change sign of an element.
+ */
+static INLINE void
+fld_tinyscale(fld_t res, const fld_t a, limb_t x)
+{
+	int i;
+	for (i = 0; i < FLD_LIMB_NUM; i++)
+		res[i] = x * a[i];
+}
+
+/*
+ * fld_scale2 is a special case of fld_tinyscale with x = 2.
+ */
+static INLINE void
+fld_scale2(fld_t res, const fld_t a)
+{
+	int i;
+	for (i = 0; i < FLD_LIMB_NUM; i++)
+		res[i] = a[i] << 1;
+}
+
+/*
+ * fld_neg is a special case of fld_tinyscale with x = -1.
+ */
+static INLINE void
+fld_neg(fld_t res, const fld_t a)
+{
+	int i;
+	for (i = 0; i < FLD_LIMB_NUM; i++)
+		res[i] = -a[i];
+}
+
+#endif