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
......@@ -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
......
......@@ -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
......@@ -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"
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