1 files changed, 46 insertions, 3 deletions
diff --git a/src/libsodium/crypto_sign/ed25519/ref10/keypair.c b/src/libsodium/crypto_sign/ed25519/ref10/keypair.c
index 7955647..2268cd6 100644
--- a/src/libsodium/crypto_sign/ed25519/ref10/keypair.c
+++ b/src/libsodium/crypto_sign/ed25519/ref10/keypair.c
@@ -2,8 +2,11 @@
 #include <string.h>
 
 #include "api.h"
-#include "randombytes.h"
 #include "crypto_hash_sha512.h"
+#include "crypto_scalarmult_curve25519.h"
+#include "randombytes.h"
+#include "utils.h"
+#include "fe.h"
 #include "ge.h"
 
 int crypto_sign_seed_keypair(unsigned char *pk, unsigned char *sk,
@@ -27,7 +30,47 @@ int crypto_sign_seed_keypair(unsigned char *pk, unsigned char *sk,
 int crypto_sign_keypair(unsigned char *pk, unsigned char *sk)
 {
     unsigned char seed[32];
+    int           ret;
+
+    randombytes_buf(seed, sizeof seed);
+    ret = crypto_sign_seed_keypair(pk, sk, seed);
+    sodium_memzero(seed, sizeof seed);
+
+    return ret;
+}
+
+int crypto_sign_ed25519_pk_to_curve25519(unsigned char *curve25519_pk,
+                                         const unsigned char *ed25519_pk)
+{
+    ge_p3 A;
+    fe    x;
+    fe    one_minus_y;
 
-    randombytes(seed,32);
-    return crypto_sign_seed_keypair(pk,sk,seed);
+    ge_frombytes_negate_vartime(&A, ed25519_pk);
+    fe_1(one_minus_y);
+    fe_sub(one_minus_y, one_minus_y, A.Y);
+    fe_invert(one_minus_y, one_minus_y);
+    fe_1(x);
+    fe_add(x, x, A.Y);
+    fe_mul(x, x, one_minus_y);
+    fe_tobytes(curve25519_pk, x);
+
+    return 0;
+}
+
+int crypto_sign_ed25519_sk_to_curve25519(unsigned char *curve25519_sk,
+                                         const unsigned char *ed25519_sk)
+{
+    unsigned char h[crypto_hash_sha512_BYTES];
+
+    crypto_hash_sha512(h, ed25519_sk,
+                       crypto_sign_ed25519_SECRETKEYBYTES -
+                       crypto_sign_ed25519_PUBLICKEYBYTES);
+    h[0] &= 248;
+    h[31] &= 127;
+    h[31] |= 64;
+    memcpy(curve25519_sk, h, crypto_scalarmult_curve25519_BYTES);
+    sodium_memzero(h, sizeof h);
+
+    return 0;
 }