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crypto_diff_fuzz_chacha20.cpp
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crypto_diff_fuzz_chacha20.cpp
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// Copyright (c) 2020-2021 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include <crypto/chacha20.h>
#include <test/fuzz/FuzzedDataProvider.h>
#include <test/fuzz/fuzz.h>
#include <test/fuzz/util.h>
#include <cstdint>
#include <vector>
/*
From https://cr.yp.to/chacha.html
chacha-merged.c version 20080118
D. J. Bernstein
Public domain.
*/
typedef unsigned int u32;
typedef unsigned char u8;
#define U8C(v) (v##U)
#define U32C(v) (v##U)
#define U8V(v) ((u8)(v)&U8C(0xFF))
#define U32V(v) ((u32)(v)&U32C(0xFFFFFFFF))
#define ROTL32(v, n) (U32V((v) << (n)) | ((v) >> (32 - (n))))
#define U8TO32_LITTLE(p) \
(((u32)((p)[0])) | ((u32)((p)[1]) << 8) | ((u32)((p)[2]) << 16) | \
((u32)((p)[3]) << 24))
#define U32TO8_LITTLE(p, v) \
do { \
(p)[0] = U8V((v)); \
(p)[1] = U8V((v) >> 8); \
(p)[2] = U8V((v) >> 16); \
(p)[3] = U8V((v) >> 24); \
} while (0)
/* ------------------------------------------------------------------------- */
/* Data structures */
typedef struct
{
u32 input[16];
} ECRYPT_ctx;
/* ------------------------------------------------------------------------- */
/* Mandatory functions */
void ECRYPT_keysetup(
ECRYPT_ctx* ctx,
const u8* key,
u32 keysize, /* Key size in bits. */
u32 ivsize); /* IV size in bits. */
void ECRYPT_ivsetup(
ECRYPT_ctx* ctx,
const u8* iv);
void ECRYPT_encrypt_bytes(
ECRYPT_ctx* ctx,
const u8* plaintext,
u8* ciphertext,
u32 msglen); /* Message length in bytes. */
/* ------------------------------------------------------------------------- */
/* Optional features */
void ECRYPT_keystream_bytes(
ECRYPT_ctx* ctx,
u8* keystream,
u32 length); /* Length of keystream in bytes. */
/* ------------------------------------------------------------------------- */
#define ROTATE(v, c) (ROTL32(v, c))
#define XOR(v, w) ((v) ^ (w))
#define PLUS(v, w) (U32V((v) + (w)))
#define PLUSONE(v) (PLUS((v), 1))
#define QUARTERROUND(a, b, c, d) \
a = PLUS(a, b); d = ROTATE(XOR(d, a), 16); \
c = PLUS(c, d); b = ROTATE(XOR(b, c), 12); \
a = PLUS(a, b); d = ROTATE(XOR(d, a), 8); \
c = PLUS(c, d); b = ROTATE(XOR(b, c), 7);
static const char sigma[] = "expand 32-byte k";
static const char tau[] = "expand 16-byte k";
void ECRYPT_keysetup(ECRYPT_ctx* x, const u8* k, u32 kbits, u32 ivbits)
{
const char* constants;
x->input[4] = U8TO32_LITTLE(k + 0);
x->input[5] = U8TO32_LITTLE(k + 4);
x->input[6] = U8TO32_LITTLE(k + 8);
x->input[7] = U8TO32_LITTLE(k + 12);
if (kbits == 256) { /* recommended */
k += 16;
constants = sigma;
} else { /* kbits == 128 */
constants = tau;
}
x->input[8] = U8TO32_LITTLE(k + 0);
x->input[9] = U8TO32_LITTLE(k + 4);
x->input[10] = U8TO32_LITTLE(k + 8);
x->input[11] = U8TO32_LITTLE(k + 12);
x->input[0] = U8TO32_LITTLE(constants + 0);
x->input[1] = U8TO32_LITTLE(constants + 4);
x->input[2] = U8TO32_LITTLE(constants + 8);
x->input[3] = U8TO32_LITTLE(constants + 12);
}
void ECRYPT_ivsetup(ECRYPT_ctx* x, const u8* iv)
{
x->input[12] = 0;
x->input[13] = 0;
x->input[14] = U8TO32_LITTLE(iv + 0);
x->input[15] = U8TO32_LITTLE(iv + 4);
}
void ECRYPT_encrypt_bytes(ECRYPT_ctx* x, const u8* m, u8* c, u32 bytes)
{
u32 x0, x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, x13, x14, x15;
u32 j0, j1, j2, j3, j4, j5, j6, j7, j8, j9, j10, j11, j12, j13, j14, j15;
u8* ctarget = nullptr;
u8 tmp[64];
uint32_t i;
if (!bytes) return;
j0 = x->input[0];
j1 = x->input[1];
j2 = x->input[2];
j3 = x->input[3];
j4 = x->input[4];
j5 = x->input[5];
j6 = x->input[6];
j7 = x->input[7];
j8 = x->input[8];
j9 = x->input[9];
j10 = x->input[10];
j11 = x->input[11];
j12 = x->input[12];
j13 = x->input[13];
j14 = x->input[14];
j15 = x->input[15];
for (;;) {
if (bytes < 64) {
for (i = 0; i < bytes; ++i)
tmp[i] = m[i];
m = tmp;
ctarget = c;
c = tmp;
}
x0 = j0;
x1 = j1;
x2 = j2;
x3 = j3;
x4 = j4;
x5 = j5;
x6 = j6;
x7 = j7;
x8 = j8;
x9 = j9;
x10 = j10;
x11 = j11;
x12 = j12;
x13 = j13;
x14 = j14;
x15 = j15;
for (i = 20; i > 0; i -= 2) {
QUARTERROUND(x0, x4, x8, x12)
QUARTERROUND(x1, x5, x9, x13)
QUARTERROUND(x2, x6, x10, x14)
QUARTERROUND(x3, x7, x11, x15)
QUARTERROUND(x0, x5, x10, x15)
QUARTERROUND(x1, x6, x11, x12)
QUARTERROUND(x2, x7, x8, x13)
QUARTERROUND(x3, x4, x9, x14)
}
x0 = PLUS(x0, j0);
x1 = PLUS(x1, j1);
x2 = PLUS(x2, j2);
x3 = PLUS(x3, j3);
x4 = PLUS(x4, j4);
x5 = PLUS(x5, j5);
x6 = PLUS(x6, j6);
x7 = PLUS(x7, j7);
x8 = PLUS(x8, j8);
x9 = PLUS(x9, j9);
x10 = PLUS(x10, j10);
x11 = PLUS(x11, j11);
x12 = PLUS(x12, j12);
x13 = PLUS(x13, j13);
x14 = PLUS(x14, j14);
x15 = PLUS(x15, j15);
x0 = XOR(x0, U8TO32_LITTLE(m + 0));
x1 = XOR(x1, U8TO32_LITTLE(m + 4));
x2 = XOR(x2, U8TO32_LITTLE(m + 8));
x3 = XOR(x3, U8TO32_LITTLE(m + 12));
x4 = XOR(x4, U8TO32_LITTLE(m + 16));
x5 = XOR(x5, U8TO32_LITTLE(m + 20));
x6 = XOR(x6, U8TO32_LITTLE(m + 24));
x7 = XOR(x7, U8TO32_LITTLE(m + 28));
x8 = XOR(x8, U8TO32_LITTLE(m + 32));
x9 = XOR(x9, U8TO32_LITTLE(m + 36));
x10 = XOR(x10, U8TO32_LITTLE(m + 40));
x11 = XOR(x11, U8TO32_LITTLE(m + 44));
x12 = XOR(x12, U8TO32_LITTLE(m + 48));
x13 = XOR(x13, U8TO32_LITTLE(m + 52));
x14 = XOR(x14, U8TO32_LITTLE(m + 56));
x15 = XOR(x15, U8TO32_LITTLE(m + 60));
j12 = PLUSONE(j12);
if (!j12) {
j13 = PLUSONE(j13);
/* stopping at 2^70 bytes per nonce is user's responsibility */
}
U32TO8_LITTLE(c + 0, x0);
U32TO8_LITTLE(c + 4, x1);
U32TO8_LITTLE(c + 8, x2);
U32TO8_LITTLE(c + 12, x3);
U32TO8_LITTLE(c + 16, x4);
U32TO8_LITTLE(c + 20, x5);
U32TO8_LITTLE(c + 24, x6);
U32TO8_LITTLE(c + 28, x7);
U32TO8_LITTLE(c + 32, x8);
U32TO8_LITTLE(c + 36, x9);
U32TO8_LITTLE(c + 40, x10);
U32TO8_LITTLE(c + 44, x11);
U32TO8_LITTLE(c + 48, x12);
U32TO8_LITTLE(c + 52, x13);
U32TO8_LITTLE(c + 56, x14);
U32TO8_LITTLE(c + 60, x15);
if (bytes <= 64) {
if (bytes < 64) {
for (i = 0; i < bytes; ++i)
ctarget[i] = c[i];
}
x->input[12] = j12;
x->input[13] = j13;
return;
}
bytes -= 64;
c += 64;
m += 64;
}
}
void ECRYPT_keystream_bytes(ECRYPT_ctx* x, u8* stream, u32 bytes)
{
u32 i;
for (i = 0; i < bytes; ++i)
stream[i] = 0;
ECRYPT_encrypt_bytes(x, stream, stream, bytes);
}
FUZZ_TARGET(crypto_diff_fuzz_chacha20)
{
FuzzedDataProvider fuzzed_data_provider{buffer.data(), buffer.size()};
ECRYPT_ctx ctx;
const std::vector<unsigned char> key = ConsumeFixedLengthByteVector(fuzzed_data_provider, 32);
ChaCha20 chacha20{MakeByteSpan(key)};
ECRYPT_keysetup(&ctx, key.data(), key.size() * 8, 0);
// ECRYPT_keysetup() doesn't set the counter and nonce to 0 while SetKey() does
static const uint8_t iv[8] = {0, 0, 0, 0, 0, 0, 0, 0};
ChaCha20::Nonce96 nonce{0, 0};
uint32_t counter{0};
ECRYPT_ivsetup(&ctx, iv);
LIMITED_WHILE (fuzzed_data_provider.ConsumeBool(), 3000) {
CallOneOf(
fuzzed_data_provider,
[&] {
const std::vector<unsigned char> key = ConsumeFixedLengthByteVector(fuzzed_data_provider, 32);
chacha20.SetKey(MakeByteSpan(key));
nonce = {0, 0};
counter = 0;
ECRYPT_keysetup(&ctx, key.data(), key.size() * 8, 0);
// ECRYPT_keysetup() doesn't set the counter and nonce to 0 while SetKey() does
uint8_t iv[8] = {0, 0, 0, 0, 0, 0, 0, 0};
ECRYPT_ivsetup(&ctx, iv);
},
[&] {
uint32_t iv_prefix = fuzzed_data_provider.ConsumeIntegral<uint32_t>();
uint64_t iv = fuzzed_data_provider.ConsumeIntegral<uint64_t>();
nonce = {iv_prefix, iv};
counter = fuzzed_data_provider.ConsumeIntegral<uint32_t>();
chacha20.Seek(nonce, counter);
ctx.input[12] = counter;
ctx.input[13] = iv_prefix;
ctx.input[14] = iv;
ctx.input[15] = iv >> 32;
},
[&] {
uint32_t integralInRange = fuzzed_data_provider.ConsumeIntegralInRange<size_t>(0, 4096);
std::vector<uint8_t> output(integralInRange);
chacha20.Keystream(MakeWritableByteSpan(output));
std::vector<uint8_t> djb_output(integralInRange);
ECRYPT_keystream_bytes(&ctx, djb_output.data(), djb_output.size());
assert(output == djb_output);
// DJB's version seeks forward to a multiple of 64 bytes after every operation. Correct for that.
uint32_t old_counter = counter;
counter += (integralInRange + 63) >> 6;
if (counter < old_counter) ++nonce.first;
if (integralInRange & 63) {
chacha20.Seek(nonce, counter);
}
assert(counter == ctx.input[12]);
},
[&] {
uint32_t integralInRange = fuzzed_data_provider.ConsumeIntegralInRange<size_t>(0, 4096);
std::vector<uint8_t> output(integralInRange);
const std::vector<uint8_t> input = ConsumeFixedLengthByteVector(fuzzed_data_provider, output.size());
chacha20.Crypt(MakeByteSpan(input), MakeWritableByteSpan(output));
std::vector<uint8_t> djb_output(integralInRange);
ECRYPT_encrypt_bytes(&ctx, input.data(), djb_output.data(), input.size());
assert(output == djb_output);
// DJB's version seeks forward to a multiple of 64 bytes after every operation. Correct for that.
uint32_t old_counter = counter;
counter += (integralInRange + 63) >> 6;
if (counter < old_counter) ++nonce.first;
if (integralInRange & 63) {
chacha20.Seek(nonce, counter);
}
assert(counter == ctx.input[12]);
});
}
}