X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=libtomcrypt%2Fsrc%2Fstream%2Fchacha%2Fchacha_crypt.c;fp=libtomcrypt%2Fsrc%2Fstream%2Fchacha%2Fchacha_crypt.c;h=6814058fea623c4561f4bc354039832edf6a2fbe;hb=66bc25938679f1d6a1d1200f329093d82a5e99b4;hp=0000000000000000000000000000000000000000;hpb=a52ee0733f420ca20224049260d6fc5cf7d8f621;p=zpackage

diff --git a/libtomcrypt/src/stream/chacha/chacha_crypt.c b/libtomcrypt/src/stream/chacha/chacha_crypt.c
new file mode 100644
index 0000000..6814058
--- /dev/null
+++ b/libtomcrypt/src/stream/chacha/chacha_crypt.c
@@ -0,0 +1,101 @@
+/* LibTomCrypt, modular cryptographic library -- Tom St Denis
+ *
+ * LibTomCrypt is a library that provides various cryptographic
+ * algorithms in a highly modular and flexible manner.
+ *
+ * The library is free for all purposes without any express
+ * guarantee it works.
+ */
+
+/* The implementation is based on:
+ * chacha-ref.c version 20080118
+ * Public domain from D. J. Bernstein
+ */
+
+#include "tomcrypt.h"
+
+#ifdef LTC_CHACHA
+
+#define QUARTERROUND(a,b,c,d) \
+  x[a] += x[b]; x[d] = ROL(x[d] ^ x[a], 16); \
+  x[c] += x[d]; x[b] = ROL(x[b] ^ x[c], 12); \
+  x[a] += x[b]; x[d] = ROL(x[d] ^ x[a],  8); \
+  x[c] += x[d]; x[b] = ROL(x[b] ^ x[c],  7);
+
+static void _chacha_block(unsigned char *output, const ulong32 *input, int rounds)
+{
+   ulong32 x[16];
+   int i;
+   XMEMCPY(x, input, sizeof(x));
+   for (i = rounds; i > 0; i -= 2) {
+      QUARTERROUND(0, 4, 8,12)
+      QUARTERROUND(1, 5, 9,13)
+      QUARTERROUND(2, 6,10,14)
+      QUARTERROUND(3, 7,11,15)
+      QUARTERROUND(0, 5,10,15)
+      QUARTERROUND(1, 6,11,12)
+      QUARTERROUND(2, 7, 8,13)
+      QUARTERROUND(3, 4, 9,14)
+   }
+   for (i = 0; i < 16; ++i) {
+     x[i] += input[i];
+     STORE32L(x[i], output + 4 * i);
+   }
+}
+
+/**
+   Encrypt (or decrypt) bytes of ciphertext (or plaintext) with ChaCha
+   @param st      The ChaCha state
+   @param in      The plaintext (or ciphertext)
+   @param inlen   The length of the input (octets)
+   @param out     [out] The ciphertext (or plaintext), length inlen
+   @return CRYPT_OK if successful
+*/
+int chacha_crypt(chacha_state *st, const unsigned char *in, unsigned long inlen, unsigned char *out)
+{
+   unsigned char buf[64];
+   unsigned long i, j;
+
+   if (inlen == 0) return CRYPT_OK; /* nothing to do */
+
+   LTC_ARGCHK(st        != NULL);
+   LTC_ARGCHK(in        != NULL);
+   LTC_ARGCHK(out       != NULL);
+   LTC_ARGCHK(st->ivlen != 0);
+
+   if (st->ksleft > 0) {
+      j = MIN(st->ksleft, inlen);
+      for (i = 0; i < j; ++i, st->ksleft--) out[i] = in[i] ^ st->kstream[64 - st->ksleft];
+      inlen -= j;
+      if (inlen == 0) return CRYPT_OK;
+      out += j;
+      in  += j;
+   }
+   for (;;) {
+     _chacha_block(buf, st->input, st->rounds);
+     if (st->ivlen == 8) {
+       /* IV-64bit, increment 64bit counter */
+       if (0 == ++st->input[12] && 0 == ++st->input[13]) return CRYPT_OVERFLOW;
+     }
+     else {
+       /* IV-96bit, increment 32bit counter */
+       if (0 == ++st->input[12]) return CRYPT_OVERFLOW;
+     }
+     if (inlen <= 64) {
+       for (i = 0; i < inlen; ++i) out[i] = in[i] ^ buf[i];
+       st->ksleft = 64 - inlen;
+       for (i = inlen; i < 64; ++i) st->kstream[i] = buf[i];
+       return CRYPT_OK;
+     }
+     for (i = 0; i < 64; ++i) out[i] = in[i] ^ buf[i];
+     inlen -= 64;
+     out += 64;
+     in  += 64;
+   }
+}
+
+#endif
+
+/* ref:         $Format:%D$ */
+/* git commit:  $Format:%H$ */
+/* commit time: $Format:%ai$ */