From 351329fbaae71bbf61ab6df6ebf94bdab7a42b70 Mon Sep 17 00:00:00 2001
From: "Le.Beta" <ccsmsblocker@gmail.com>
Date: Tue, 19 Mar 2019 10:53:47 +0800
Subject: [PATCH] Add chacha12 and chacha20

code form sectun
---
 lib/chacha20.c | 127 +++++++++++++++++++++++++++++++++++++++++++++++++
 lib/chacha20.h |   9 ++++
 2 files changed, 136 insertions(+)
 create mode 100644 lib/chacha20.c
 create mode 100644 lib/chacha20.h

diff --git a/lib/chacha20.c b/lib/chacha20.c
new file mode 100644
index 0000000..85c49af
--- /dev/null
+++ b/lib/chacha20.c
@@ -0,0 +1,127 @@
+#include <stdint.h>
+#include <string.h>
+#include "chacha20.h"
+
+static inline void u32t8le(uint32_t v, uint8_t p[4]) {
+    p[0] = v & 0xff;
+    p[1] = (v >> 8) & 0xff;
+    p[2] = (v >> 16) & 0xff;
+    p[3] = (v >> 24) & 0xff;
+}
+
+static inline uint32_t u8t32le(uint8_t p[4]) {
+    uint32_t value = p[3];
+
+    value = (value << 8) | p[2];
+    value = (value << 8) | p[1];
+    value = (value << 8) | p[0];
+
+    return value;
+}
+
+static inline uint32_t rotl32(uint32_t x, int n) {
+    // http://blog.regehr.org/archives/1063
+    return x << n | (x >> (-n & 31));
+}
+
+// https://tools.ietf.org/html/rfc7539#section-2.1
+static void chacha20_quarterround(uint32_t *x, int a, int b, int c, int d) {
+    x[a] += x[b]; x[d] = rotl32(x[d] ^ x[a], 16);
+    x[c] += x[d]; x[b] = rotl32(x[b] ^ x[c], 12);
+    x[a] += x[b]; x[d] = rotl32(x[d] ^ x[a],  8);
+    x[c] += x[d]; x[b] = rotl32(x[b] ^ x[c],  7);
+}
+
+static void chacha20_serialize(uint32_t in[16], uint8_t output[64]) {
+    int i;
+    for (i = 0; i < 16; i++) {
+        u32t8le(in[i], output + (i << 2));
+    }
+}
+
+static void chacha20_block(uint32_t in[16], uint8_t out[64], int num_rounds) {
+    int i;
+    uint32_t x[16];
+
+    memcpy(x, in, sizeof(uint32_t) * 16);
+
+    for (i = num_rounds; i > 0; i -= 2) {
+        chacha20_quarterround(x, 0, 4,  8, 12);
+        chacha20_quarterround(x, 1, 5,  9, 13);
+        chacha20_quarterround(x, 2, 6, 10, 14);
+        chacha20_quarterround(x, 3, 7, 11, 15);
+        chacha20_quarterround(x, 0, 5, 10, 15);
+        chacha20_quarterround(x, 1, 6, 11, 12);
+        chacha20_quarterround(x, 2, 7,  8, 13);
+        chacha20_quarterround(x, 3, 4,  9, 14);
+    }
+
+    for (i = 0; i < 16; i++) {
+        x[i] += in[i];
+    }
+
+    chacha20_serialize(x, out);
+}
+
+// https://tools.ietf.org/html/rfc7539#section-2.3
+static void chacha20_init_state(uint32_t s[16], uint8_t key[32], uint32_t counter, uint8_t nonce[12]) {
+    int i;
+
+    // refer: https://dxr.mozilla.org/mozilla-beta/source/security/nss/lib/freebl/chacha20.c
+    // convert magic number to string: "expand 32-byte k"
+    s[0] = 0x61707865;
+    s[1] = 0x3320646e;
+    s[2] = 0x79622d32;
+    s[3] = 0x6b206574;
+
+    for (i = 0; i < 8; i++) {
+        s[4 + i] = u8t32le(key + i * 4);
+    }
+
+    s[12] = counter;
+
+    for (i = 0; i < 3; i++) {
+        s[13 + i] = u8t32le(nonce + i * 4);
+    }
+}
+void ChaCha12XOR(uint8_t key[32], uint32_t counter, uint8_t nonce[12], uint8_t *in, uint8_t *out, int inlen) {
+    int i, j;
+
+    uint32_t s[16];
+    uint8_t block[64];
+
+    chacha20_init_state(s, key, counter, nonce);
+
+    for (i = 0; i < inlen; i += 64) {
+        chacha20_block(s, block, 12);
+        s[12]++;
+
+        for (j = i; j < i + 64; j++) {
+            if (j >= inlen) {
+                break;
+            }
+            out[j] = in[j] ^ block[j - i];
+        }
+    }
+}
+
+void ChaCha20XOR(uint8_t key[32], uint32_t counter, uint8_t nonce[12], uint8_t *in, uint8_t *out, int inlen) {
+    int i, j;
+
+    uint32_t s[16];
+    uint8_t block[64];
+
+    chacha20_init_state(s, key, counter, nonce);
+
+    for (i = 0; i < inlen; i += 64) {
+        chacha20_block(s, block, 20);
+        s[12]++;
+
+        for (j = i; j < i + 64; j++) {
+            if (j >= inlen) {
+                break;
+            }
+            out[j] = in[j] ^ block[j - i];
+        }
+    }
+}
diff --git a/lib/chacha20.h b/lib/chacha20.h
new file mode 100644
index 0000000..5131d7f
--- /dev/null
+++ b/lib/chacha20.h
@@ -0,0 +1,9 @@
+#ifndef __CHACHA20_H
+#define __CHACHA20_H
+#include <stdint.h>
+
+void ChaCha12XOR(uint8_t key[32], uint32_t counter, uint8_t nonce[12], uint8_t *input, uint8_t *output, int inputlen);
+
+void ChaCha20XOR(uint8_t key[32], uint32_t counter, uint8_t nonce[12], uint8_t *input, uint8_t *output, int inputlen);
+
+#endif
\ No newline at end of file