From 5d69c6a2661bba0a22f3ecfd517e2e9767a38346 Mon Sep 17 00:00:00 2001
From: Cem Keylan <cem@ckyln.com>
Date: Fri, 16 Oct 2020 17:47:01 +0300
Subject: add tools

---
 usr.bin/signify/mod_ed25519.c | 143 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 143 insertions(+)
 create mode 100644 usr.bin/signify/mod_ed25519.c

(limited to 'usr.bin/signify/mod_ed25519.c')

diff --git a/usr.bin/signify/mod_ed25519.c b/usr.bin/signify/mod_ed25519.c
new file mode 100644
index 0000000..aac481a
--- /dev/null
+++ b/usr.bin/signify/mod_ed25519.c
@@ -0,0 +1,143 @@
+/* $OpenBSD: mod_ed25519.c,v 1.1 2014/01/08 05:00:01 tedu Exp $ */
+
+/*
+ * Public Domain, Authors: Daniel J. Bernstein, Niels Duif, Tanja Lange,
+ * Peter Schwabe, Bo-Yin Yang.
+ * Copied from supercop-20130419/crypto_sign/ed25519/ref/ed25519.c
+ */
+
+#include "crypto_api.h"
+
+#include "ge25519.h"
+
+static void get_hram(unsigned char *hram, const unsigned char *sm, const unsigned char *pk, unsigned char *playground, unsigned long long smlen)
+{
+  unsigned long long i;
+
+  for (i =  0;i < 32;++i)    playground[i] = sm[i];
+  for (i = 32;i < 64;++i)    playground[i] = pk[i-32];
+  for (i = 64;i < smlen;++i) playground[i] = sm[i];
+
+  crypto_hash_sha512(hram,playground,smlen);
+}
+
+#ifndef VERIFYONLY
+int crypto_sign_ed25519_keypair(
+    unsigned char *pk,
+    unsigned char *sk
+    )
+{
+  sc25519 scsk;
+  ge25519 gepk;
+  unsigned char extsk[64];
+  int i;
+
+  randombytes(sk, 32);
+  crypto_hash_sha512(extsk, sk, 32);
+  extsk[0] &= 248;
+  extsk[31] &= 127;
+  extsk[31] |= 64;
+
+  sc25519_from32bytes(&scsk,extsk);
+  
+  ge25519_scalarmult_base(&gepk, &scsk);
+  ge25519_pack(pk, &gepk);
+  for(i=0;i<32;i++)
+    sk[32 + i] = pk[i];
+  return 0;
+}
+
+int crypto_sign_ed25519(
+    unsigned char *sm,unsigned long long *smlen,
+    const unsigned char *m,unsigned long long mlen,
+    const unsigned char *sk
+    )
+{
+  sc25519 sck, scs, scsk;
+  ge25519 ger;
+  unsigned char r[32];
+  unsigned char s[32];
+  unsigned char extsk[64];
+  unsigned long long i;
+  unsigned char hmg[crypto_hash_sha512_BYTES];
+  unsigned char hram[crypto_hash_sha512_BYTES];
+
+  crypto_hash_sha512(extsk, sk, 32);
+  extsk[0] &= 248;
+  extsk[31] &= 127;
+  extsk[31] |= 64;
+
+  *smlen = mlen+64;
+  for(i=0;i<mlen;i++)
+    sm[64 + i] = m[i];
+  for(i=0;i<32;i++)
+    sm[32 + i] = extsk[32+i];
+
+  crypto_hash_sha512(hmg, sm+32, mlen+32); /* Generate k as h(extsk[32],...,extsk[63],m) */
+
+  /* Computation of R */
+  sc25519_from64bytes(&sck, hmg);
+  ge25519_scalarmult_base(&ger, &sck);
+  ge25519_pack(r, &ger);
+  
+  /* Computation of s */
+  for(i=0;i<32;i++)
+    sm[i] = r[i];
+
+  get_hram(hram, sm, sk+32, sm, mlen+64);
+
+  sc25519_from64bytes(&scs, hram);
+  sc25519_from32bytes(&scsk, extsk);
+  sc25519_mul(&scs, &scs, &scsk);
+  
+  sc25519_add(&scs, &scs, &sck);
+
+  sc25519_to32bytes(s,&scs); /* cat s */
+  for(i=0;i<32;i++)
+    sm[32 + i] = s[i]; 
+
+  return 0;
+}
+#endif
+int crypto_sign_ed25519_open(
+    unsigned char *m,unsigned long long *mlen,
+    const unsigned char *sm,unsigned long long smlen,
+    const unsigned char *pk
+    )
+{
+  unsigned int i;
+  int ret;
+  unsigned char t2[32];
+  ge25519 get1, get2;
+  sc25519 schram, scs;
+  unsigned char hram[crypto_hash_sha512_BYTES];
+
+  *mlen = (unsigned long long) -1;
+  if (smlen < 64) return -1;
+
+  if (ge25519_unpackneg_vartime(&get1, pk)) return -1;
+
+  get_hram(hram,sm,pk,m,smlen);
+
+  sc25519_from64bytes(&schram, hram);
+
+  sc25519_from32bytes(&scs, sm+32);
+
+  ge25519_double_scalarmult_vartime(&get2, &get1, &schram, &ge25519_base, &scs);
+  ge25519_pack(t2, &get2);
+
+  ret = crypto_verify_32(sm, t2);
+
+  if (!ret)
+  {
+    for(i=0;i<smlen-64;i++)
+      m[i] = sm[i + 64];
+    *mlen = smlen-64;
+  }
+  else
+  {
+    for(i=0;i<smlen-64;i++)
+      m[i] = 0;
+  }
+  return ret;
+}
-- 
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