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Split ChaCha20 into aligned/unaligned variants

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This commit is contained in:
Pieter Wuille
2022-09-21 16:36:57 -04:00
parent ceb74b844c
commit e37bcaa0a6
2 changed files with 97 additions and 45 deletions
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86
src/crypto/chacha20.cpp
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@@ -8,6 +8,7 @@
#include <crypto/common.h>
#include <crypto/chacha20.h>
#include <algorithm>
#include <string.h>
constexpr static inline uint32_t rotl32(uint32_t v, int c) { return (v << c) | (v >> (32 - c)); }
@@ -23,7 +24,7 @@ constexpr static inline uint32_t rotl32(uint32_t v, int c) { return (v << c) | (
static const unsigned char sigma[] = "expand 32-byte k";
static const unsigned char tau[] = "expand 16-byte k";
void ChaCha20::SetKey(const unsigned char* k, size_t keylen)
void ChaCha20Aligned::SetKey(const unsigned char* k, size_t keylen)
{
const unsigned char *constants;
@@ -51,37 +52,34 @@ void ChaCha20::SetKey(const unsigned char* k, size_t keylen)
input[15] = 0;
}
ChaCha20::ChaCha20()
ChaCha20Aligned::ChaCha20Aligned()
{
memset(input, 0, sizeof(input));
}
ChaCha20::ChaCha20(const unsigned char* k, size_t keylen)
ChaCha20Aligned::ChaCha20Aligned(const unsigned char* k, size_t keylen)
{
SetKey(k, keylen);
}
void ChaCha20::SetIV(uint64_t iv)
void ChaCha20Aligned::SetIV(uint64_t iv)
{
input[14] = iv;
input[15] = iv >> 32;
}
void ChaCha20::Seek(uint64_t pos)
void ChaCha20Aligned::Seek(uint64_t pos)
{
input[12] = pos;
input[13] = pos >> 32;
}
void ChaCha20::Keystream(unsigned char* c, size_t bytes)
inline void ChaCha20Aligned::Keystream64(unsigned char* c, size_t blocks)
{
uint32_t x0, x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, x13, x14, x15;
uint32_t j0, j1, j2, j3, j4, j5, j6, j7, j8, j9, j10, j11, j12, j13, j14, j15;
unsigned char *ctarget = nullptr;
unsigned char tmp[64];
unsigned int i;
if (!bytes) return;
if (!blocks) return;
j0 = input[0];
j1 = input[1];
@@ -101,10 +99,6 @@ void ChaCha20::Keystream(unsigned char* c, size_t bytes)
j15 = input[15];
for (;;) {
if (bytes < 64) {
ctarget = c;
c = tmp;
}
x0 = j0;
x1 = j1;
x2 = j2;
@@ -171,28 +165,22 @@ void ChaCha20::Keystream(unsigned char* c, size_t bytes)
WriteLE32(c + 56, x14);
WriteLE32(c + 60, x15);
if (bytes <= 64) {
if (bytes < 64) {
for (i = 0;i < bytes;++i) ctarget[i] = c[i];
}
if (blocks == 1) {
input[12] = j12;
input[13] = j13;
return;
}
bytes -= 64;
blocks -= 1;
c += 64;
}
}
void ChaCha20::Crypt(const unsigned char* m, unsigned char* c, size_t bytes)
inline void ChaCha20Aligned::Crypt64(const unsigned char* m, unsigned char* c, size_t blocks)
{
uint32_t x0, x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, x13, x14, x15;
uint32_t j0, j1, j2, j3, j4, j5, j6, j7, j8, j9, j10, j11, j12, j13, j14, j15;
unsigned char *ctarget = nullptr;
unsigned char tmp[64];
unsigned int i;
if (!bytes) return;
if (!blocks) return;
j0 = input[0];
j1 = input[1];
@@ -212,14 +200,6 @@ void ChaCha20::Crypt(const unsigned char* m, unsigned char* c, size_t bytes)
j15 = input[15];
for (;;) {
if (bytes < 64) {
// if m has fewer than 64 bytes available, copy m to tmp and
// read from tmp instead
for (i = 0;i < bytes;++i) tmp[i] = m[i];
m = tmp;
ctarget = c;
c = tmp;
}
x0 = j0;
x1 = j1;
x2 = j2;
@@ -303,16 +283,48 @@ void ChaCha20::Crypt(const unsigned char* m, unsigned char* c, size_t bytes)
WriteLE32(c + 56, x14);
WriteLE32(c + 60, x15);
if (bytes <= 64) {
if (bytes < 64) {
for (i = 0;i < bytes;++i) ctarget[i] = c[i];
}
if (blocks == 1) {
input[12] = j12;
input[13] = j13;
return;
}
bytes -= 64;
blocks -= 1;
c += 64;
m += 64;
}
}
void ChaCha20::Keystream(unsigned char* c, size_t bytes)
{
if (!bytes) return;
if (bytes >= 64) {
size_t blocks = bytes / 64;
m_aligned.Keystream64(c, blocks);
c += blocks * 64;
bytes -= blocks * 64;
}
if (bytes) {
unsigned char buffer[64];
m_aligned.Keystream64(buffer, 1);
memcpy(c, buffer, bytes);
}
}
void ChaCha20::Crypt(const unsigned char* m, unsigned char* c, size_t bytes)
{
if (!bytes) return;
if (bytes >= 64) {
size_t blocks = bytes / 64;
m_aligned.Crypt64(m, c, blocks);
c += blocks * 64;
m += blocks * 64;
bytes -= blocks * 64;
}
if (bytes) {
unsigned char buffer[64];
m_aligned.Keystream64(buffer, 1);
for (unsigned i = 0; i < bytes; i++) {
c[i] = m[i] ^ buffer[i];
}
}
}