public static int vxed25519_verify(ISha512 sha512provider,
byte[] vrf_out,
byte[] signature,
byte[] curve25519_pubkey,
byte[] msg, int msg_len)
{
int[] u = new int[10];
int[] y = new int[10];
byte[] ed_pubkey = new byte[32];
byte[] strict = new byte[32];
byte[] verifybuf = new byte[crypto_additions.MAX_MSG_LEN + 160]; /* working buffer */
byte[] verifybuf2 = new byte[crypto_additions.MAX_MSG_LEN + 160]; /* working buffer #2 ?? !!! */
Ge_p3 Bv = new Ge_p3();
if (msg_len > crypto_additions.MAX_MSG_LEN)
{
return(-1);
}
/* Convert the Curve25519 public key into an Ed25519 public key.
*
* y = (u - 1) / (u + 1)
*
* NOTE: u=-1 is converted to y=0 since fe_invert is mod-exp
*/
Fe_frombytes.fe_frombytes(u, curve25519_pubkey);
Fe_tobytes.fe_tobytes(strict, u);
if (Crypto_verify_32.crypto_verify_32(strict, curve25519_pubkey) != 0)
{
return(0);
}
Fe_montx_to_edy.fe_montx_to_edy(y, u);
Fe_tobytes.fe_tobytes(ed_pubkey, y);
Elligator.calculate_Bv(sha512provider, Bv, verifybuf, ed_pubkey, msg, msg_len);
Array.Copy(signature, 0, verifybuf, 0, 96);
Array.Copy(msg, 0, verifybuf, 96, msg_len);
/* Then perform a signature verification, return 0 on success */
/* The below call has a strange API: */
/* verifybuf = V || h || s || message */
/* verifybuf2 = used as buffer, gets the VRF output if success */
if (Vopen_modified.crypto_vsign_open_modified(sha512provider, verifybuf2, verifybuf, 96 + msg_len, ed_pubkey, Bv) == 0)
{
Array.Copy(verifybuf2, 0, vrf_out, 0, 32);
return(0);
}
else
{
//memset(vrf_out, 0, 32);
return(-1);
}
}
public static int vxed25510_sign(ISha512 sha512provider,
byte[] signature_out,
byte[] curve25519_privkey,
byte[] msg, int msg_len,
byte[] random)
{
byte[] a = new byte[32];
byte[] aneg = new byte[32];
byte[] A = new byte[32];
Ge_p3 Bv = new Ge_p3();
Ge_p3 ed_pubkey_point = new Ge_p3();
byte[] sigbuf = new byte[crypto_additions.MAX_MSG_LEN + 160]; /* working buffer */
byte sign_bit = 0;
if (msg_len > crypto_additions.MAX_MSG_LEN)
{
//memset(signature_out, 0, 96);
return(-1);
}
/* Convert the Curve25519 privkey to an Ed25519 public key */
Ge_scalarmult_base.ge_scalarmult_base(ed_pubkey_point, curve25519_privkey);
Ge_p3_tobytes.ge_p3_tobytes(A, ed_pubkey_point);
/* Force Edwards sign bit to zero */
sign_bit = (byte)((A[31] & 0x80) >> 7);
Array.Copy(curve25519_privkey, 0, a, 0, 32);
Sc_neg.sc_neg(aneg, a);
Sc_cmov.sc_cmov(a, aneg, sign_bit);
A[31] &= 0x7F;
Elligator.calculate_Bv_and_V(sha512provider, Bv, signature_out, sigbuf, a, A, msg, msg_len);
/* Perform an Ed25519 signature with explicit private key */
Vsign_modified.crypto_vsign_modified(sha512provider, sigbuf, msg, msg_len, a, A, random, Bv, signature_out /*V*/);
Array.Copy(sigbuf, 0, signature_out, 32, 64);
Zeroize.zeroize(a, 32);
Zeroize.zeroize(aneg, 32);
return(0);
}
