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The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.8 and up.
package org.bouncycastle.pqc.crypto.falcon;
class FalconRNG
{
byte[] bd;
long bdummy_u64;
int ptr;
byte[] sd;
long sdummy_u64;
int type;
FalconConversions convertor;
FalconRNG()
{
this.bd = new byte[512];
this.bdummy_u64 = 0;
this.ptr = 0;
this.sd = new byte[256];
this.sdummy_u64 = 0;
this.type = 0;
this.convertor = new FalconConversions();
}
void prng_init(SHAKE256 src)
{
/*
* To ensure reproducibility for a given seed, we
* must enforce little-endian interpretation of
* the state words.
*/
byte[] tmp = new byte[56];
long th, tl;
int i;
src.inner_shake256_extract(tmp, 0, 56);
for (i = 0; i < 14; i++)
{
int w;
w = (tmp[(i << 2) + 0] & 0xff)
| ((tmp[(i << 2) + 1] & 0xff) << 8)
| ((tmp[(i << 2) + 2] & 0xff) << 16)
| ((tmp[(i << 2) + 3] & 0xff) << 24);
System.arraycopy(convertor.int_to_bytes(w), 0, this.sd, i << 2, 4);
}
tl = (convertor.bytes_to_int(this.sd, 48) & 0xffffffffL);
th = (convertor.bytes_to_int(this.sd, 52) & 0xffffffffL);
System.arraycopy(convertor.long_to_bytes(tl + (th << 32)), 0, this.sd, 48, 8);
this.prng_refill();
}
/*
* PRNG based on ChaCha20.
*
* State consists in key (32 bytes) then IV (16 bytes) and block counter
* (8 bytes). Normally, we should not care about local endianness (this
* is for a PRNG), but for the NIST competition we need reproducible KAT
* vectors that work across architectures, so we enforce little-endian
* interpretation where applicable. Moreover, output words are "spread
* out" over the output buffer with the interleaving pattern that is
* naturally obtained from the AVX2 implementation that runs eight
* ChaCha20 instances in parallel.
*
* The block counter is XORed into the first 8 bytes of the IV.
*/
void prng_refill()
{
int[] CW = {
0x61707865, 0x3320646e, 0x79622d32, 0x6b206574
};
long cc;
int u;
/*
* State uses local endianness. Only the output bytes must be
* converted to little endian (if used on a big-endian machine).
*/
// cc = *(uint64_t *)(p->state.d + 48);
cc = convertor.bytes_to_long(this.sd, 48);
for (u = 0; u < 8; u++)
{
int[] state = new int[16];
int v;
int i;
// memcpy(&state[0], CW, sizeof CW);
System.arraycopy(CW, 0, state, 0, CW.length);
// memcpy(&state[4], p->state.d, 48);
System.arraycopy(convertor.bytes_to_int_array(this.sd, 0, 12), 0, state, 4, 12);
state[14] ^= (int)cc;
state[15] ^= (int)(cc >>> 32);
for (i = 0; i < 10; i++)
{
QROUND(0, 4, 8, 12, state);
QROUND(1, 5, 9, 13, state);
QROUND(2, 6, 10, 14, state);
QROUND(3, 7, 11, 15, state);
QROUND(0, 5, 10, 15, state);
QROUND(1, 6, 11, 12, state);
QROUND(2, 7, 8, 13, state);
QROUND(3, 4, 9, 14, state);
}
for (v = 0; v < 4; v++)
{
state[v] += CW[v];
}
for (v = 4; v < 14; v++)
{
// state[v] += ((uint32_t *)p->state.d)[v - 4];
// we multiply the -4 by 4 to account for 4 bytes per int
state[v] += convertor.bytes_to_int(sd, (4 * v) - 16);
}
// state[14] += ((uint32_t *)p->state.d)[10]
// ^ (uint32_t)cc;
state[14] += convertor.bytes_to_int(sd, 40) ^ ((int)cc);
// state[15] += ((uint32_t *)p->state.d)[11]
// ^ (uint32_t)(cc >> 32);
state[15] += convertor.bytes_to_int(sd, 44) ^ ((int)(cc >>> 32));
cc++;
/*
* We mimic the interleaving that is used in the AVX2
* implementation.
*/
for (v = 0; v < 16; v++)
{
// p->buf.d[(u << 2) + (v << 5) + 0] =
// (uint8_t)state[v];
// p->buf.d[(u << 2) + (v << 5) + 1] =
// (uint8_t)(state[v] >> 8);
// p->buf.d[(u << 2) + (v << 5) + 2] =
// (uint8_t)(state[v] >> 16);
// p->buf.d[(u << 2) + (v << 5) + 3] =
// (uint8_t)(state[v] >> 24);
bd[(u << 2) + (v << 5) + 0] =
(byte)state[v];
bd[(u << 2) + (v << 5) + 1] =
(byte)(state[v] >>> 8);
bd[(u << 2) + (v << 5) + 2] =
(byte)(state[v] >>> 16);
bd[(u << 2) + (v << 5) + 3] =
(byte)(state[v] >>> 24);
}
}
// *(uint64_t *)(p->state.d + 48) = cc;
System.arraycopy(convertor.long_to_bytes(cc), 0, sd, 48, 8);
this.ptr = 0;
}
/* see inner.h */
void prng_get_bytes(byte[] srcdst, int dst, int len)
{
int buf;
buf = dst;
while (len > 0)
{
int clen;
clen = (bd.length) - ptr;
if (clen > len)
{
clen = len;
}
// memcpy(buf, p->buf.d, clen);
System.arraycopy(bd, 0, srcdst, buf, clen);
buf += clen;
len -= clen;
ptr += clen;
if (ptr == bd.length)
{
this.prng_refill();
}
}
}
private void QROUND(int a, int b, int c, int d, int[] state)
{
state[a] += state[b];
state[d] ^= state[a];
state[d] = (state[d] << 16) | (state[d] >>> 16);
state[c] += state[d];
state[b] ^= state[c];
state[b] = (state[b] << 12) | (state[b] >>> 20);
state[a] += state[b];
state[d] ^= state[a];
state[d] = (state[d] << 8) | (state[d] >>> 24);
state[c] += state[d];
state[b] ^= state[c];
state[b] = (state[b] << 7) | (state[b] >>> 25);
}
long prng_get_u64()
{
int u;
/*
* If there are less than 9 bytes in the buffer, we refill it.
* This means that we may drop the last few bytes, but this allows
* for faster extraction code. Also, it means that we never leave
* an empty buffer.
*/
u = this.ptr;
if (u >= (this.bd.length) - 9)
{
this.prng_refill();
u = 0;
}
this.ptr = u + 8;
/*
* On systems that use little-endian encoding and allow
* unaligned accesses, we can simply read the data where it is.
*/
return (this.bd[u + 0] & 0xffL)
| ((this.bd[u + 1] & 0xffL) << 8)
| ((this.bd[u + 2] & 0xffL) << 16)
| ((this.bd[u + 3] & 0xffL) << 24)
| ((this.bd[u + 4] & 0xffL) << 32)
| ((this.bd[u + 5] & 0xffL) << 40)
| ((this.bd[u + 6] & 0xffL) << 48)
| ((this.bd[u + 7] & 0xffL) << 56);
}
byte prng_get_u8()
{
byte v;
v = this.bd[this.ptr++];
if (this.ptr == this.bd.length)
{
this.prng_refill();
}
return v;
}
}
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