File tweetnacl/patches/tweetnacl-derivepubkey.diff artifact 22ab288973 part of check-in 54a51a61b6

--- a/tweetnacl.c.new
+++ b/tweetnacl.c.new
@@ -653,13 +653,15 @@
   scalarmult(p,q,s);
 }
 
-int crypto_sign_keypair(u8 *pk, u8 *sk)
+int crypto_sign_keypair(u8 *pk, u8 *sk, u8 generate_sk)
 {
   u8 d[64];
   gf p[4];
   int i;
 
-  randombytes(sk, 32);
+  if (generate_sk) {
+    randombytes(sk, 32);
+  }
   crypto_hash(d, sk, 32);
   d[0] &= 248;
   d[31] &= 127;
--- a/tweetnacl.h.new
+++ b/tweetnacl.h.new
@@ -211,7 +211,7 @@
 #define crypto_sign_ed25519_tweet_SECRETKEYBYTES 64
 extern int crypto_sign_ed25519_tweet(unsigned char *,unsigned long long *,const unsigned char *,unsigned long long,const unsigned char *);
 extern int crypto_sign_ed25519_tweet_open(unsigned char *,unsigned long long *,const unsigned char *,unsigned long long,const unsigned char *);
-extern int crypto_sign_ed25519_tweet_keypair(unsigned char *,unsigned char *);
+extern int crypto_sign_ed25519_tweet_keypair(unsigned char *,unsigned char *, unsigned char);
 #define crypto_sign_ed25519_tweet_VERSION "-"
 #define crypto_sign_ed25519 crypto_sign_ed25519_tweet
 #define crypto_sign_ed25519_open crypto_sign_ed25519_tweet_open