Update to latest ref10-extract ed25519

libaxolotl/jni/curve25519-jni.c

@@ -76,17 +76,19 @@ JNIEXPORT jbyteArray JNICALL Java_org_whispersystems_libaxolotl_ecc_Curve25519_c
 }
 
 JNIEXPORT jbyteArray JNICALL Java_org_whispersystems_libaxolotl_ecc_Curve25519_calculateSignature
-  (JNIEnv *env, jclass clazz, jbyteArray privateKey, jbyteArray message)
+  (JNIEnv *env, jclass clazz, jbyteArray random, jbyteArray privateKey, jbyteArray message)
 {
     jbyteArray signature       = (*env)->NewByteArray(env, 64);
     uint8_t*   signatureBytes  = (uint8_t*)(*env)->GetByteArrayElements(env, signature, 0);
+    uint8_t*   randomBytes     = (uint8_t*)(*env)->GetByteArrayElements(env, random, 0);
     uint8_t*   privateKeyBytes = (uint8_t*)(*env)->GetByteArrayElements(env, privateKey, 0);
     uint8_t*   messageBytes    = (uint8_t*)(*env)->GetByteArrayElements(env, message, 0);
     jsize      messageLength   = (*env)->GetArrayLength(env, message);
 
-    curve25519_sign(signatureBytes, privateKeyBytes, messageBytes, messageLength);
+    curve25519_sign(signatureBytes, privateKeyBytes, messageBytes, messageLength, randomBytes);
 
     (*env)->ReleaseByteArrayElements(env, signature, signatureBytes, 0);
+    (*env)->ReleaseByteArrayElements(env, random, randomBytes, 0);
     (*env)->ReleaseByteArrayElements(env, privateKey, privateKeyBytes, 0);
     (*env)->ReleaseByteArrayElements(env, message, messageBytes, 0);
 

libaxolotl/jni/ed25519/additions/curve_sigs.c

@@ -4,11 +4,10 @@
 #include "crypto_sign.h"
 
 void curve25519_keygen(unsigned char* curve25519_pubkey_out,
-                       unsigned char* curve25519_privkey_in)
+                       const unsigned char* curve25519_privkey_in)
 {
-  ge_p3 ed_pubkey_point; /* Ed25519 pubkey point */
-  unsigned char ed_pubkey[32]; /* privkey followed by pubkey */
-  fe ed_y, one, ed_y_plus_one, one_minus_ed_y, inv_one_minus_ed_y;
+  ge_p3 ed; /* Ed25519 pubkey point */
+  fe ed_y, ed_y_plus_one, one_minus_ed_y, inv_one_minus_ed_y;
   fe mont_x;
 
   /* Perform a fixed-base multiplication of the Edwards base point,
@@ -17,49 +16,49 @@ void curve25519_keygen(unsigned char* curve25519_pubkey_out,
      convert Curve25519's "montgomery" x-coordinate into an Ed25519
      "edwards" y-coordinate:
 
-     mont_x = (ed_y +1 1) / (1 - ed_y)
-  */
+     mont_x = (ed_y + 1) / (1 - ed_y)
+     
+     with projective coordinates:
 
-  ge_scalarmult_base(&ed_pubkey_point, curve25519_privkey_in);
-  ge_p3_tobytes(ed_pubkey, &ed_pubkey_point);
-  ed_pubkey[31] = ed_pubkey[31] & 0x7F; /* Mask off sign bit */
-  fe_frombytes(ed_y, ed_pubkey);
+     mont_x = (ed_y + ed_z) / (ed_z - ed_y)
+  */
 
-  fe_1(one);
-  fe_add(ed_y_plus_one, ed_y, one);
-  fe_sub(one_minus_ed_y, one, ed_y);  
+  ge_scalarmult_base(&ed, curve25519_privkey_in);
+  fe_add(ed_y_plus_one, ed.Y, ed.Z);
+  fe_sub(one_minus_ed_y, ed.Z, ed.Y);  
   fe_invert(inv_one_minus_ed_y, one_minus_ed_y);
   fe_mul(mont_x, ed_y_plus_one, inv_one_minus_ed_y);
-  fe_tobytes(curve25519_pubkey_out, mont_x);    
+  fe_tobytes(curve25519_pubkey_out, mont_x);
 }
 
 void curve25519_sign(unsigned char* signature_out,
-                     unsigned char* curve25519_privkey,
-                     unsigned char* msg, unsigned long msg_len)
+                     const unsigned char* curve25519_privkey,
+                     const unsigned char* msg, const unsigned long msg_len,
+                     const unsigned char* random)
 {
   ge_p3 ed_pubkey_point; /* Ed25519 pubkey point */
-  unsigned char ed_keypair[64]; /* privkey followed by pubkey */
+  unsigned char ed_pubkey[32]; /* Ed25519 encoded pubkey */
   unsigned char sigbuf[msg_len + 64]; /* working buffer */
   unsigned long long sigbuf_out_len = 0;
   unsigned char sign_bit = 0;
 
-  /* Convert the Curve25519 privkey to an Ed25519 keypair */
-  memmove(ed_keypair, curve25519_privkey, 32);
+  /* Convert the Curve25519 privkey to an Ed25519 public key */
   ge_scalarmult_base(&ed_pubkey_point, curve25519_privkey);
-  ge_p3_tobytes(ed_keypair + 32, &ed_pubkey_point);
-  sign_bit = ed_keypair[63] & 0x80;
+  ge_p3_tobytes(ed_pubkey, &ed_pubkey_point);
+  sign_bit = ed_pubkey[31] & 0x80;
 
   /* Perform an Ed25519 signature with explicit private key */
-  crypto_sign_modified(sigbuf, &sigbuf_out_len, msg, msg_len, ed_keypair);
+  crypto_sign_modified(sigbuf, &sigbuf_out_len, msg, msg_len, curve25519_privkey,
+                       ed_pubkey, random);
   memmove(signature_out, sigbuf, 64);
 
   /* Encode the sign bit into signature (in unused high bit of S) */
    signature_out[63] |= sign_bit;
 }
 
-int curve25519_verify(unsigned char* signature,
-                      unsigned char* curve25519_pubkey,
-                      unsigned char* msg, unsigned long msg_len)
+int curve25519_verify(const unsigned char* signature,
+                      const unsigned char* curve25519_pubkey,
+                      const unsigned char* msg, const unsigned long msg_len)
 {
   fe mont_x, mont_x_minus_one, mont_x_plus_one, inv_mont_x_plus_one;
   fe one;
@@ -87,11 +86,15 @@ int curve25519_verify(unsigned char* signature,
 
   /* Copy the sign bit, and remove it from signature */
   ed_pubkey[31] |= (signature[63] & 0x80);
-  signature[63] &= 0x7F;
-
   memmove(verifybuf, signature, 64);
+  verifybuf[63] &= 0x7F;
+
   memmove(verifybuf+64, msg, msg_len);
 
   /* Then perform a normal Ed25519 verification, return 0 on success */
+  /* The below call has a strange API: */
+  /* verifybuf = R || S || message */
+  /* verifybuf2 = internal to next call gets a copy of verifybuf, S gets 
+     replaced with pubkey for hashing, then the whole thing gets zeroized */
   return crypto_sign_open(verifybuf2, &some_retval, verifybuf, 64 + msg_len, ed_pubkey);
 }

libaxolotl/jni/ed25519/additions/curve_sigs.h

@@ -2,24 +2,45 @@
 #ifndef __CURVE_SIGS_H__
 #define __CURVE_SIGS_H__
 
-void curve25519_keygen(unsigned char* curve25519_pubkey_out,
-                       unsigned char* curve25519_privkey_in);
+void curve25519_keygen(unsigned char* curve25519_pubkey_out, /* 32 bytes */
+                       const unsigned char* curve25519_privkey_in); /* 32 bytes */
 
-void curve25519_sign(unsigned char* signature_out,
-                     unsigned char* curve25519_privkey,
-                     unsigned char* msg, unsigned long msg_len);
+void curve25519_sign(unsigned char* signature_out, /* 64 bytes */
+                     const unsigned char* curve25519_privkey, /* 32 bytes */
+                     const unsigned char* msg, const unsigned long msg_len,
+                     const unsigned char* random); /* 64 bytes */
 
 /* returns 0 on success */
-int curve25519_verify(unsigned char* signature,
-                      unsigned char* curve25519_pubkey,                      
-                      unsigned char* msg, unsigned long msg_len);
+int curve25519_verify(const unsigned char* signature, /* 64 bytes */
+                      const unsigned char* curve25519_pubkey, /* 32 bytes */               
+                      const unsigned char* msg, const unsigned long msg_len);
 
 /* helper function - modified version of crypto_sign() to use 
-   explicit private key */
+   explicit private key.  In particular:
+
+   sk : private key
+   pk : public key
+   m  : message
+   prefix : 0xFE || [0xFF]*31
+   q  : main subgroup order
+
+   The prefix is chosen to distinguish the two SHA512 uses below, since
+   prefix is an invalid encoding for R (it would encode a "field element"
+   of 2^255 - 2).  0xFF*32 is set aside for use in ECDH protocols, which
+   is why the first byte here ix 0xFE.
+
+   sig_nonce = (random XOR SHA512(prefix || sk || m)) % q
+   R = g^sig_nonce
+   M = SHA512(R || pk || m)
+   S = sig_nonce + (m * sk)
+   signature = (R || S)
+ */
 int crypto_sign_modified(
   unsigned char *sm,unsigned long long *smlen,
   const unsigned char *m,unsigned long long mlen,
-  const unsigned char *sk
+  const unsigned char *sk, /* Curve/Ed25519 private key */
+  const unsigned char *pk, /* Ed25519 public key */
+  const unsigned char *random /* 64 bytes random to XOR into nonce */
   );
 
 #endif

libaxolotl/jni/ed25519/additions/sha512.c

@@ -1,5 +1,6 @@
 #include "sha512.h"
 #include "sph_sha2.h"
+#include "zeroize.h"
 
 int crypto_hash_sha512_ref(unsigned char *output ,const unsigned char *input,
                            unsigned long long len)
@@ -8,6 +9,6 @@ int crypto_hash_sha512_ref(unsigned char *output ,const unsigned char *input,
   sph_sha512_init(&ctx);  
   sph_sha512(&ctx, input, len);
   sph_sha512_close(&ctx, output);
+  zeroize((unsigned char*)&ctx, sizeof(ctx));
   return 0;
 }
-

libaxolotl/jni/ed25519/additions/sign_modified.c

@@ -3,6 +3,7 @@
 #include "crypto_hash_sha512.h"
 #include "ge.h"
 #include "sc.h"
+#include "zeroize.h"
 
 /* NEW: Compare to pristine crypto_sign() 
    Uses explicit private key for nonce derivation and as scalar,
@@ -11,23 +12,31 @@
 int crypto_sign_modified(
   unsigned char *sm,unsigned long long *smlen,
   const unsigned char *m,unsigned long long mlen,
-  const unsigned char *sk
+  const unsigned char *sk, const unsigned char* pk,
+  const unsigned char* random
 )
 {
-  unsigned char pk[32];
-  unsigned char az[64];
   unsigned char nonce[64];
   unsigned char hram[64];
   ge_p3 R;
-
-  memmove(pk,sk + 32,32);
+  int count=0;
 
   *smlen = mlen + 64;
   memmove(sm + 64,m,mlen);
   memmove(sm + 32,sk,32); /* NEW: Use privkey directly for nonce derivation */
-  crypto_hash_sha512(nonce,sm + 32,mlen + 32);
+
+  /* NEW : add prefix to separate hash uses - see .h */
+  sm[0] = 0xFE;
+  for (count = 1; count < 32; count++)
+    sm[count] = 0xFF;
+
+  crypto_hash_sha512(nonce,sm,mlen + 64);
   memmove(sm + 32,pk,32);
 
+  /* NEW: XOR random into nonce */
+  for (count=0; count < 64; count++)
+    nonce[count] ^= random[count];
+
   sc_reduce(nonce);
   ge_scalarmult_base(&R,nonce);
   ge_p3_tobytes(sm,&R);
@@ -36,5 +45,11 @@ int crypto_sign_modified(
   sc_reduce(hram);
   sc_muladd(sm + 32,hram,sk,nonce); /* NEW: Use privkey directly */
 
+  /* NEW: Dummy call to hopefully erase any traces of privkey or 
+     nonce left in the stack from prev call to this func. */
+  volatile unsigned char* p = sm+64;
+  sc_muladd(sm+64,hram,hram,hram);
+
+  zeroize(nonce, 64);
   return 0;
 }

libaxolotl/jni/ed25519/additions/zeroize.c

@@ -0,0 +1,10 @@
+
+void zeroize(unsigned char* b, unsigned long len)
+{
+  unsigned long count = 0;
+  unsigned long retval = 0;
+  volatile unsigned char *p = b;
+
+  for (count = 0; count < len; count++)
+    p[count] = 0;
+}

libaxolotl/jni/ed25519/additions/zeroize.h

@@ -0,0 +1,6 @@
+#ifndef __ZEROIZE_H__
+#define __ZEROIZE_H__
+
+void zeroize(unsigned char* b, unsigned long len);
+
+#endif

libaxolotl/jni/ed25519/main/main.c

@@ -1,6 +1,6 @@
 #include <stdio.h>
 #include <string.h>
-#include "sha512.h"
+#include "crypto_hash_sha512.h"
 #include "curve_sigs.h"
 
 int main(int argc, char* argv[])
@@ -10,6 +10,7 @@ int main(int argc, char* argv[])
   unsigned char signature[64];
   unsigned char msg[100];
   unsigned long long msg_len = 100;
+  unsigned char random[64];
 
   /* Initialize pubkey, privkey, msg */
   memset(msg, 0, 100);
@@ -21,21 +22,84 @@ int main(int argc, char* argv[])
 
   privkey[8] = 189; /* just so there's some bits set */
 
+
+  /* SHA512 test */
+  unsigned char sha512_input[112] = "abcdefghbcdefghicdefghijdefghijkefghijklfghijklmghijklmnhijklmnoijklmnopjklmnopqklmnopqrlmnopqrsmnopqrstnopqrstu";
+  unsigned char sha512_correct_output[64] =
+{
+0x8E, 0x95, 0x9B, 0x75, 0xDA, 0xE3, 0x13, 0xDA,
+0x8C, 0xF4, 0xF7, 0x28, 0x14, 0xFC, 0x14, 0x3F,
+0x8F, 0x77, 0x79, 0xC6, 0xEB, 0x9F, 0x7F, 0xA1,
+0x72, 0x99, 0xAE, 0xAD, 0xB6, 0x88, 0x90, 0x18,
+0x50, 0x1D, 0x28, 0x9E, 0x49, 0x00, 0xF7, 0xE4,
+0x33, 0x1B, 0x99, 0xDE, 0xC4, 0xB5, 0x43, 0x3A,
+0xC7, 0xD3, 0x29, 0xEE, 0xB6, 0xDD, 0x26, 0x54,
+0x5E, 0x96, 0xE5, 0x5B, 0x87, 0x4B, 0xE9, 0x09
+};
+  unsigned char sha512_actual_output[64];
+
+  crypto_hash_sha512_ref(sha512_actual_output, sha512_input, sizeof(sha512_input));
+  if (memcmp(sha512_actual_output, sha512_correct_output, 64) != 0)
+    printf("SHA512 bad #1\n");
+  else
+    printf("SHA512 good #1\n");
+
+  sha512_input[111] ^= 1;
+
+  crypto_hash_sha512_ref(sha512_actual_output, sha512_input, sizeof(sha512_input));
+  if (memcmp(sha512_actual_output, sha512_correct_output, 64) != 0)
+    printf("SHA512 good #2\n");
+  else
+    printf("SHA512 bad #2\n");
+  
+  /* Signature test */
   curve25519_keygen(pubkey, privkey);
 
-  curve25519_sign(signature, privkey, msg, msg_len);
+  curve25519_sign(signature, privkey, msg, msg_len, random);
 
   if (curve25519_verify(signature, pubkey, msg, msg_len) == 0)
-    printf("success #1\n");
+    printf("Signature good #1\n");
   else
-    printf("failure #1\n");
+    printf("Signature bad #1\n");
 
   signature[0] ^= 1;
 
   if (curve25519_verify(signature, pubkey, msg, msg_len) == 0)
-    printf("failure #2\n");
+    printf("Signature bad #2\n");
   else
-    printf("success #2\n");
+    printf("Signature good #2\n");
+
+
+  printf("Random testing...\n");
+  for (int count = 0; count < 10000; count++) {
+    unsigned char b[64];
+    crypto_hash_sha512_ref(b, privkey, 32);
+    memmove(privkey, b, 32);
+    crypto_hash_sha512_ref(b, privkey, 32);
+    memmove(random, b, 64);
+
+    privkey[0] &= 248;
+    privkey[31] &= 63;
+    privkey[31] |= 64;
+
+    curve25519_keygen(pubkey, privkey);
+
+    curve25519_sign(signature, privkey, msg, msg_len, random);
+
+    if (curve25519_verify(signature, pubkey, msg, msg_len) != 0) {
+      printf("failure #1 %d\n", count);
+      return -1;
+    }
 
+    if (b[63] & 1)
+      signature[count % 64] ^= 1;
+    else
+      msg[count % 100] ^= 1;
+    if (curve25519_verify(signature, pubkey, msg, msg_len) == 0) {
+      printf("failure #2 %d\n", count);
+      return -1;
+    }
+  }
+  printf("OK\n");
   return 1;
 }

libaxolotl/src/main/java/org/whispersystems/libaxolotl/ecc/Curve25519.java

@@ -39,7 +39,7 @@ public class Curve25519 {
   private static native byte[] generatePublicKey(byte[] privateKey);
   private static native byte[] generatePrivateKey(byte[] random, boolean ephemeral);
 
-  private static native byte[]  calculateSignature(byte[] privateKey, byte[] message);
+  private static native byte[]  calculateSignature(byte[] random, byte[] privateKey, byte[] message);
   private static native boolean verifySignature(byte[] publicKey, byte[] message, byte[] signature);
 
   public static ECKeyPair generateKeyPair(boolean ephemeral) {
@@ -55,7 +55,8 @@ public class Curve25519 {
   }
 
   static byte[] calculateSignature(ECPrivateKey privateKey, byte[] message) {
-    return calculateSignature(((DjbECPrivateKey)privateKey).getPrivateKey(), message);
+    byte[] random = getRandom(32);
+    return calculateSignature(random, ((DjbECPrivateKey)privateKey).getPrivateKey(), message);
   }
 
   static boolean verifySignature(ECPublicKey publicKey, byte[] message, byte[] signature) {
@@ -83,4 +84,15 @@ public class Curve25519 {
     return generatePrivateKey(privateKey, ephemeral);
   }
 
+  private static byte[] getRandom(int size) {
+    try {
+      byte[] random = new byte[size];
+      SecureRandom.getInstance("SHA1PRNG").nextBytes(random);
+
+      return random;
+    } catch (NoSuchAlgorithmException e) {
+      throw new AssertionError(e);
+    }
+  }
+
 }