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Add chacha20_streaming_init api for use by tcp obfuscator

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This commit is contained in:
Ludvig Strigeus 2018-12-10 23:13:13 +01:00
parent 13158f9d90
commit aec9415e44
2 changed files with 40 additions and 1 deletions
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29
crypto/chacha20poly1305.cpp
View file

@ -13,6 +13,7 @@
#include "crypto_ops.h"
#include <string.h>
#include <assert.h>
#include "util.h"
enum {
CHACHA20_IV_SIZE = 16,
@ -631,3 +632,31 @@ bool xchacha20poly1305_decrypt(uint8 *dst, const uint8 *src, const size_t src_le
return ret;
}
void chacha20_streaming_init(chacha20_streaming *state, uint8 key[CHACHA20POLY1305_KEYLEN]) {
state->left = 0;
uint32 *st = state->state;
WriteLE64((uint8*)st, 0x3320646e61707865);
WriteLE64((uint8*)st + 8, 0x6b20657479622d32);
Write64((uint8*)st + 16, Read64(key + 0));
Write64((uint8*)st + 24, Read64(key + 8));
Write64((uint8*)st + 32, Read64(key + 16));
Write64((uint8*)st + 40, Read64(key + 24));
Write64((uint8*)st + 48, 0);
Write64((uint8*)st + 56, 0);
}
void chacha20_streaming_crypt(chacha20_streaming *state, uint8 *dst, size_t size) {
uint32 left = state->left;
while (size) {
if (left == 0) {
memset(state->buf, 0, sizeof(state->buf));
chacha20_crypt((struct chacha20_ctx *)state->state, state->buf, state->buf, sizeof(state->buf));
left = 64;
}
size_t step = left > size ? size : left;
crypto_xor(postinc(dst, step), state->buf + 64 - exch(left, left - (uint32)step), exch(size, size - step));
}
state->left = left;
}

12
crypto/chacha20poly1305.h
View file

@ -36,4 +36,14 @@ bool xchacha20poly1305_decrypt(uint8 *dst, const uint8 *src, const size_t src_le
void poly1305_get_mac(const uint8 *src, size_t src_len,
const uint8 *ad, const size_t ad_len,
const uint64 nonce, const uint8 key[CHACHA20POLY1305_KEYLEN],
uint8 mac[CHACHA20POLY1305_AUTHTAGLEN]);
uint8 mac[CHACHA20POLY1305_AUTHTAGLEN]);
struct chacha20_streaming {
uint32 left;
uint8 buf[64];
uint32 state[16];
};
void chacha20_streaming_init(chacha20_streaming *state, uint8 key[CHACHA20POLY1305_KEYLEN]);
void chacha20_streaming_crypt(chacha20_streaming *state, uint8 *dst, size_t size);