Commit be113f0b authored by Yawning Angel's avatar Yawning Angel
Browse files

Add Curve25519->Ed25519 support to ed25519-donna (Not yet used). 

This needs to be done to allow for the possibility of removing the
ref10 code at a later date, though it is not performance critical.
When integrated by kludging it into tor, it passes unit tests, and is
twice as fast.
parent b7aa3074

src/ext/ed25519/donna/README.tor

+4 −0
Original line number Diff line number Diff line
@@ -20,6 +20,10 @@ as of 8757bd4cd209cb032853ece0ce413f122eef212c. 
    * There's an implementation of multiplicative key blinding so we

      can use it for next-gen hidden service descriptors.



    * There's an implementation of 'convert a curve25519 key to an

      ed25519 key' so we can do cross-certification with curve25519

      keys.



 * `ED25519_FN(ed25519_randombytes_unsafe)` is now static.



 * `ed25519-randombytes-custom.h` has the appropriate code to call

src/ext/ed25519/donna/ed25519_donna_tor.h

+3 −0
Original line number Diff line number Diff line
@@ -27,4 +27,7 @@ int ed25519_donna_blind_secret_key(unsigned char *out, const unsigned char *inp, 
int ed25519_donna_blind_public_key(unsigned char *out, const unsigned char *inp,

  const unsigned char *param);



int ed25519_donna_pubkey_from_curve25519_pubkey(unsigned char *out,

  const unsigned char *inp, int signbit);



#endif

src/ext/ed25519/donna/ed25519_tor.c

+23 −0
Original line number Diff line number Diff line
@@ -139,6 +139,8 @@ ED25519_FN(curved25519_scalarmult_basepoint) (curved25519_key pk, const curved25 
    * Routines that deal with the private key now use the expanded form.



    * Support for multiplicative key blinding has been added.



    * Support for converting a Curve25519 key to an Ed25519 key has been added.

 */



int
@@ -317,5 +319,26 @@ ed25519_donna_blind_public_key(unsigned char *out, const unsigned char *inp, 
  return 0;

}



int

ed25519_donna_pubkey_from_curve25519_pubkey(unsigned char *out,

  const unsigned char *inp, int signbit)

{

  static const bignum25519 one = { 1 };

  bignum25519 ALIGN(16) u, uminus1, uplus1, inv_uplus1, y;



  /* Prop228: y = (u-1)/(u+1) */

  curve25519_expand(u, inp);

  curve25519_sub(uminus1, u, one);

  curve25519_add(uplus1, u, one);

  curve25519_recip(inv_uplus1, uplus1);

  curve25519_mul(y, uminus1, inv_uplus1);

  curve25519_contract(out, y);



  /* Propagate sign. */

  out[31] |= (!!signbit) << 7;



  return 0;

}



#include "test-internals.c"