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using System;
using Org.BouncyCastle.Security;
using Org.BouncyCastle.Utilities;
namespace Org.BouncyCastle.Pqc.Crypto.Falcon
{
internal class FalconNist
{
private FalconCodec codec;
private FalconVrfy vrfy;
private FalconCommon common;
private SecureRandom random;
private uint logn;
private uint noncelen;
private int CRYPTO_BYTES;
private int CRYPTO_PUBLICKEYBYTES;
private int CRYPTO_SECRETKEYBYTES;
internal uint NonceLength => this.noncelen;
internal uint LogN => this.logn;
internal int CryptoBytes => this.CRYPTO_BYTES;
internal FalconNist(SecureRandom random, uint logn, uint noncelen)
{
this.logn = logn;
this.codec = new FalconCodec();
this.common = new FalconCommon();
this.vrfy = new FalconVrfy(this.common);
this.random = random;
this.noncelen = noncelen;
int n = (int)1 << (int)logn;
this.CRYPTO_PUBLICKEYBYTES = 1 + (14 * n / 8);
if (logn == 10)
{
this.CRYPTO_SECRETKEYBYTES = 2305;
this.CRYPTO_BYTES = 1330;
}
else if (logn == 9 || logn == 8)
{
this.CRYPTO_SECRETKEYBYTES = 1 + (6 * n * 2 / 8) + n;
this.CRYPTO_BYTES = 690; // TODO find what the byte length is here when not at degree 9 or 10
}
else if (logn == 7 || logn == 6)
{
this.CRYPTO_SECRETKEYBYTES = 1 + (7 * n * 2 / 8) + n;
this.CRYPTO_BYTES = 690;
}
else
{
this.CRYPTO_SECRETKEYBYTES = 1 + (n * 2) + n;
this.CRYPTO_BYTES = 690;
}
}
internal int crypto_sign_keypair(out byte[] pk, out byte[] fEnc, out byte[] gEnc, out byte[] FEnc)
{
byte[] sk = new byte[CRYPTO_SECRETKEYBYTES];
pk = new byte[CRYPTO_PUBLICKEYBYTES];
int n = (int)1 << (int)this.logn;
SHAKE256 rng = new SHAKE256();
sbyte[] f = new sbyte[n], g = new sbyte[n], F = new sbyte[n];
ushort[] h = new ushort[n];
byte[] seed = new byte[48];
int u, v;
FalconKeygen keygen = new FalconKeygen(this.codec, this.vrfy);
/*
* Generate key pair.
*/
this.random.NextBytes(seed);
rng.i_shake256_init();
rng.i_shake256_inject(seed, 0, seed.Length);
rng.i_shake256_flip();
keygen.keygen(rng, f, 0, g, 0, F, 0, null, 0, h, 0, this.logn);
/*
* Encode private key.
*/
sk[0] = (byte)(0x50 + this.logn);
u = 1;
v = this.codec.trim_i8_encode(sk, u, CRYPTO_SECRETKEYBYTES - u,
f, 0, this.logn, this.codec.max_fg_bits[this.logn]);
if (v == 0) {
// TODO check which exception types to use here
throw new InvalidOperationException("f encode failed");
}
fEnc = Arrays.CopyOfRange(sk, u, u + v);
u += v;
v = this.codec.trim_i8_encode(sk, u, CRYPTO_SECRETKEYBYTES - u,
g, 0, this.logn, this.codec.max_fg_bits[this.logn]);
if (v == 0) {
throw new InvalidOperationException("g encode failed");
}
gEnc = Arrays.CopyOfRange(sk, u, u + v);
u += v;
v = this.codec.trim_i8_encode(sk, u, CRYPTO_SECRETKEYBYTES - u,
F, 0, this.logn, this.codec.max_FG_bits[this.logn]);
if (v == 0) {
throw new InvalidOperationException("F encode failed");
}
FEnc = Arrays.CopyOfRange(sk, u, u + v);
u += v;
if (u != CRYPTO_SECRETKEYBYTES) {
throw new InvalidOperationException("secret key encoding failed");
}
/*
* Encode public key.
*/
pk[0] = (byte)(0x00 + this.logn);
v = this.codec.modq_encode(pk, 1, CRYPTO_PUBLICKEYBYTES - 1, h, 0, this.logn);
if (v != CRYPTO_PUBLICKEYBYTES - 1) {
throw new InvalidOperationException("public key encoding failed");
}
pk = Arrays.CopyOfRange(pk, 1, pk.Length);
return 0;
}
internal byte[] crypto_sign(bool attached, byte[] sm,
byte[] msrc, int m, uint mlen,
byte[] sksrc, int sk)
{
// TEMPALLOC union {
// uint8_t b[72 * 1024];
// uint64_t dummy_u64;
// fpr dummy_fpr;
// } tmp;
int u, v, sig_len;
int n = (int)1 << (int)this.logn;
sbyte[] f = new sbyte[n],
g = new sbyte[n],
F = new sbyte[n],
G = new sbyte[n];
short[] sig = new short[n];
ushort[] hm = new ushort[n];
byte[] seed = new byte[48],
nonce = new byte[this.noncelen];
byte[] esig = new byte[this.CRYPTO_BYTES - 2 - this.noncelen];
SHAKE256 sc = new SHAKE256();
FalconSign signer = new FalconSign(this.common);
// /*
// * Decode the private key.
// */
// if (sksrc[sk+0] != 0x50 + this.logn) {
// throw new ArgumentException("private key header incorrect");
// }
u = 0;
v = this.codec.trim_i8_decode(f, 0, this.logn, this.codec.max_fg_bits[this.logn],
sksrc, sk + u, CRYPTO_SECRETKEYBYTES - u);
if (v == 0)
{
throw new InvalidOperationException("f decode failed");
}
u += v;
v = this.codec.trim_i8_decode(g, 0, this.logn, this.codec.max_fg_bits[this.logn],
sksrc, sk + u, CRYPTO_SECRETKEYBYTES - u);
if (v == 0)
{
throw new InvalidOperationException("g decode failed");
}
u += v;
v = this.codec.trim_i8_decode(F, 0, this.logn, this.codec.max_FG_bits[this.logn],
sksrc, sk + u, CRYPTO_SECRETKEYBYTES - u);
if (v == 0)
{
throw new InvalidOperationException("F decode failed");
}
u += v;
if (u != CRYPTO_SECRETKEYBYTES - 1)
{
throw new InvalidOperationException("full Key not used");
}
if (this.vrfy.complete_private(G, 0, f, 0, g, 0, F, 0, this.logn, new ushort[2 * n],0) == 0)
{
throw new InvalidOperationException("complete private failed");
}
/*
* Create a random nonce (40 bytes).
*/
this.random.NextBytes(nonce);
/*
* Hash message nonce + message into a vector.
*/
sc.i_shake256_init();
sc.i_shake256_inject(nonce,0,nonce.Length);
sc.i_shake256_inject(msrc,m, (int)mlen);
sc.i_shake256_flip();
this.common.hash_to_point_vartime(sc, hm, 0, this.logn);
/*
* Initialize a RNG.
*/
this.random.NextBytes(seed);
sc.i_shake256_init();
sc.i_shake256_inject(seed, 0, seed.Length);
sc.i_shake256_flip();
/*
* Compute the signature.
*/
signer.sign_dyn(sig, 0, sc, f, 0, g, 0, F, 0, G, 0, hm, 0, this.logn, new FalconFPR[10 * n], 0);
if (attached)
{
/*
* Encode the signature. Format is:
* signature header 1 bytes
* nonce 40 bytes
* signature slen bytes
*/
esig[0] = (byte)(0x20 + logn);
sig_len = codec.comp_encode(esig, 1, esig.Length - 1, sig, 0, logn);
if (sig_len == 0)
{
throw new InvalidOperationException("signature failed to generate");
}
sig_len++;
}
else
{
sig_len = codec.comp_encode(esig, 0, esig.Length, sig, 0, logn);
if (sig_len == 0)
{
throw new InvalidOperationException("signature failed to generate");
}
}
// header
sm[0] = (byte)(0x30 + logn);
// nonce
Array.Copy(nonce, 0, sm, 1, noncelen);
// signature
Array.Copy(esig, 0, sm, 1 + noncelen, sig_len);
return Arrays.CopyOfRange(sm, 0, 1 + (int)noncelen + sig_len);
}
internal int crypto_sign_open(bool attached, byte[] sig_encoded, byte[] nonce, byte[] m,
byte[] pksrc, int pk)
{
int sig_len, msg_len;
int n = (int)1 << (int)this.logn;
ushort[] h = new ushort[n],
hm = new ushort[n];
short[] sig = new short[n];
SHAKE256 sc = new SHAKE256();
/*
* Decode public key.
*/
// if (pksrc[pk+0] != 0x00 + this.logn) {
// return -1;
// }
if (this.codec.modq_decode(h, 0, this.logn, pksrc, pk, CRYPTO_PUBLICKEYBYTES - 1)
!= CRYPTO_PUBLICKEYBYTES - 1)
{
return -1;
}
this.vrfy.to_ntt_monty(h, 0, this.logn);
/*
* Find nonce, signature, message length.
*/
// if (smlen < 2 + this.noncelen) {
// return -1;
// }
// sig_len = ((int)sm[0] << 8) | (int)sm[1];
sig_len = sig_encoded.Length;
// if (sig_len > (smlen - 2 - this.noncelen)) {
// return -1;
// }
// msg_len = smlen - 2 - this.noncelen - sig_len;
msg_len = m.Length;
/*
* Decode signature.
*/
// esig = sm + 2 + this.noncelen + msg_len;
if (attached)
{
if (sig_len < 1 || sig_encoded[0] != (byte)(0x20 + this.logn))
{
return -1;
}
if (this.codec.comp_decode(sig, 0, this.logn, sig_encoded,
1, sig_len - 1) != sig_len - 1)
{
return -1;
}
}
else
{
if (sig_len < 1 || this.codec.comp_decode(sig, 0, this.logn, sig_encoded,
0, sig_len) != sig_len)
{
return -1;
}
}
/*
* Hash nonce + message into a vector.
*/
sc.i_shake256_init();
// sc.i_shake256_inject(sm + 2, this.noncelen + msg_len);
sc.i_shake256_inject(nonce, 0, (int)this.noncelen);
sc.i_shake256_inject(m, 0, m.Length);
sc.i_shake256_flip();
this.common.hash_to_point_vartime(sc, hm, 0, this.logn);
/*
* Verify signature.
*/
if (!this.vrfy.verify_raw(hm, 0, sig, 0, h, 0, this.logn, new ushort[n], 0)) {
return -1;
}
/*
* Return plaintext. - not in use
*/
// Array.Copy(sm + 2 + this.noncelen, m, msg_len);
// *mlen = msg_len;
return 0;
}
}
}
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