1 files changed, 73 insertions, 0 deletions
diff --git a/libs/libaxolotl/src/curve25519/ed25519/fe_frombytes.c b/libs/libaxolotl/src/curve25519/ed25519/fe_frombytes.c
new file mode 100644
index 0000000000..5c17917487
--- /dev/null
+++ b/libs/libaxolotl/src/curve25519/ed25519/fe_frombytes.c
@@ -0,0 +1,73 @@
+#include "fe.h"
+#include "crypto_int64.h"
+#include "crypto_uint64.h"
+
+static crypto_uint64 load_3(const unsigned char *in)
+{
+  crypto_uint64 result;
+  result = (crypto_uint64) in[0];
+  result |= ((crypto_uint64) in[1]) << 8;
+  result |= ((crypto_uint64) in[2]) << 16;
+  return result;
+}
+
+static crypto_uint64 load_4(const unsigned char *in)
+{
+  crypto_uint64 result;
+  result = (crypto_uint64) in[0];
+  result |= ((crypto_uint64) in[1]) << 8;
+  result |= ((crypto_uint64) in[2]) << 16;
+  result |= ((crypto_uint64) in[3]) << 24;
+  return result;
+}
+
+/*
+Ignores top bit of h.
+*/
+
+void fe_frombytes(fe h,const unsigned char *s)
+{
+  crypto_int64 h0 = load_4(s);
+  crypto_int64 h1 = load_3(s + 4) << 6;
+  crypto_int64 h2 = load_3(s + 7) << 5;
+  crypto_int64 h3 = load_3(s + 10) << 3;
+  crypto_int64 h4 = load_3(s + 13) << 2;
+  crypto_int64 h5 = load_4(s + 16);
+  crypto_int64 h6 = load_3(s + 20) << 7;
+  crypto_int64 h7 = load_3(s + 23) << 5;
+  crypto_int64 h8 = load_3(s + 26) << 4;
+  crypto_int64 h9 = (load_3(s + 29) & 8388607) << 2;
+  crypto_int64 carry0;
+  crypto_int64 carry1;
+  crypto_int64 carry2;
+  crypto_int64 carry3;
+  crypto_int64 carry4;
+  crypto_int64 carry5;
+  crypto_int64 carry6;
+  crypto_int64 carry7;
+  crypto_int64 carry8;
+  crypto_int64 carry9;
+
+  carry9 = (h9 + (crypto_int64) (1<<24)) >> 25; h0 += carry9 * 19; h9 -= carry9 << 25;
+  carry1 = (h1 + (crypto_int64) (1<<24)) >> 25; h2 += carry1; h1 -= carry1 << 25;
+  carry3 = (h3 + (crypto_int64) (1<<24)) >> 25; h4 += carry3; h3 -= carry3 << 25;
+  carry5 = (h5 + (crypto_int64) (1<<24)) >> 25; h6 += carry5; h5 -= carry5 << 25;
+  carry7 = (h7 + (crypto_int64) (1<<24)) >> 25; h8 += carry7; h7 -= carry7 << 25;
+
+  carry0 = (h0 + (crypto_int64) (1<<25)) >> 26; h1 += carry0; h0 -= carry0 << 26;
+  carry2 = (h2 + (crypto_int64) (1<<25)) >> 26; h3 += carry2; h2 -= carry2 << 26;
+  carry4 = (h4 + (crypto_int64) (1<<25)) >> 26; h5 += carry4; h4 -= carry4 << 26;
+  carry6 = (h6 + (crypto_int64) (1<<25)) >> 26; h7 += carry6; h6 -= carry6 << 26;
+  carry8 = (h8 + (crypto_int64) (1<<25)) >> 26; h9 += carry8; h8 -= carry8 << 26;
+
+  h[0] = h0;
+  h[1] = h1;
+  h[2] = h2;
+  h[3] = h3;
+  h[4] = h4;
+  h[5] = h5;
+  h[6] = h6;
+  h[7] = h7;
+  h[8] = h8;
+  h[9] = h9;
+}