--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtomcrypt/src/prngs/chacha20.c	Fri Feb 09 21:44:05 2018 +0800
@@ -0,0 +1,247 @@
+/* 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 idea of re-keying loosely follows the approach used in:
+  * http://bxr.su/OpenBSD/lib/libc/crypt/arc4random.c
+  */
+
+#include "tomcrypt.h"
+
+#ifdef LTC_CHACHA20_PRNG
+
+const struct ltc_prng_descriptor chacha20_prng_desc =
+{
+   "chacha20",
+   40,
+   &chacha20_prng_start,
+   &chacha20_prng_add_entropy,
+   &chacha20_prng_ready,
+   &chacha20_prng_read,
+   &chacha20_prng_done,
+   &chacha20_prng_export,
+   &chacha20_prng_import,
+   &chacha20_prng_test
+};
+
+/**
+  Start the PRNG
+  @param prng The PRNG state to initialize
+  @return CRYPT_OK if successful
+*/
+int chacha20_prng_start(prng_state *prng)
+{
+   LTC_ARGCHK(prng != NULL);
+   prng->ready = 0;
+   XMEMSET(&prng->chacha.ent, 0, sizeof(prng->chacha.ent));
+   prng->chacha.idx = 0;
+   LTC_MUTEX_INIT(&prng->lock)
+   return CRYPT_OK;
+}
+
+/**
+  Add entropy to the PRNG state
+  @param in       The data to add
+  @param inlen    Length of the data to add
+  @param prng     PRNG state to update
+  @return CRYPT_OK if successful
+*/
+int chacha20_prng_add_entropy(const unsigned char *in, unsigned long inlen, prng_state *prng)
+{
+   unsigned char buf[40];
+   unsigned long i;
+   int err;
+
+   LTC_ARGCHK(prng != NULL);
+   LTC_ARGCHK(in != NULL);
+   LTC_ARGCHK(inlen > 0);
+
+   LTC_MUTEX_LOCK(&prng->lock);
+   if (prng->ready) {
+      /* chacha20_prng_ready() was already called, do "rekey" operation */
+      if ((err = chacha_keystream(&prng->chacha.s, buf, sizeof(buf))) != CRYPT_OK) goto LBL_UNLOCK;
+      for(i = 0; i < inlen; i++) buf[i % sizeof(buf)] ^= in[i];
+      /* key 32 bytes, 20 rounds */
+      if ((err = chacha_setup(&prng->chacha.s, buf, 32, 20)) != CRYPT_OK)      goto LBL_UNLOCK;
+      /* iv 8 bytes */
+      if ((err = chacha_ivctr64(&prng->chacha.s, buf + 32, 8, 0)) != CRYPT_OK) goto LBL_UNLOCK;
+      /* clear KEY + IV */
+      zeromem(buf, sizeof(buf));
+   }
+   else {
+      /* chacha20_prng_ready() was not called yet, add entropy to ent buffer */
+      while (inlen--) prng->chacha.ent[prng->chacha.idx++ % sizeof(prng->chacha.ent)] ^= *in++;
+   }
+   err = CRYPT_OK;
+LBL_UNLOCK:
+   LTC_MUTEX_UNLOCK(&prng->lock);
+   return err;
+}
+
+/**
+  Make the PRNG ready to read from
+  @param prng   The PRNG to make active
+  @return CRYPT_OK if successful
+*/
+int chacha20_prng_ready(prng_state *prng)
+{
+   int err;
+
+   LTC_ARGCHK(prng != NULL);
+
+   LTC_MUTEX_LOCK(&prng->lock);
+   if (prng->ready)                                                    { err = CRYPT_OK; goto LBL_UNLOCK; }
+   /* key 32 bytes, 20 rounds */
+   if ((err = chacha_setup(&prng->chacha.s, prng->chacha.ent, 32, 20)) != CRYPT_OK)      goto LBL_UNLOCK;
+   /* iv 8 bytes */
+   if ((err = chacha_ivctr64(&prng->chacha.s, prng->chacha.ent + 32, 8, 0)) != CRYPT_OK) goto LBL_UNLOCK;
+   XMEMSET(&prng->chacha.ent, 0, sizeof(prng->chacha.ent));
+   prng->chacha.idx = 0;
+   prng->ready = 1;
+LBL_UNLOCK:
+   LTC_MUTEX_UNLOCK(&prng->lock);
+   return err;
+}
+
+/**
+  Read from the PRNG
+  @param out      Destination
+  @param outlen   Length of output
+  @param prng     The active PRNG to read from
+  @return Number of octets read
+*/
+unsigned long chacha20_prng_read(unsigned char *out, unsigned long outlen, prng_state *prng)
+{
+   if (outlen == 0 || prng == NULL || out == NULL) return 0;
+   LTC_MUTEX_LOCK(&prng->lock);
+   if (!prng->ready) { outlen = 0; goto LBL_UNLOCK; }
+   if (chacha_keystream(&prng->chacha.s, out, outlen) != CRYPT_OK) outlen = 0;
+LBL_UNLOCK:
+   LTC_MUTEX_UNLOCK(&prng->lock);
+   return outlen;
+}
+
+/**
+  Terminate the PRNG
+  @param prng   The PRNG to terminate
+  @return CRYPT_OK if successful
+*/
+int chacha20_prng_done(prng_state *prng)
+{
+   int err;
+   LTC_ARGCHK(prng != NULL);
+   LTC_MUTEX_LOCK(&prng->lock);
+   prng->ready = 0;
+   err = chacha_done(&prng->chacha.s);
+   LTC_MUTEX_UNLOCK(&prng->lock);
+   LTC_MUTEX_DESTROY(&prng->lock);
+   return err;
+}
+
+/**
+  Export the PRNG state
+  @param out       [out] Destination
+  @param outlen    [in/out] Max size and resulting size of the state
+  @param prng      The PRNG to export
+  @return CRYPT_OK if successful
+*/
+int chacha20_prng_export(unsigned char *out, unsigned long *outlen, prng_state *prng)
+{
+   unsigned long len = chacha20_prng_desc.export_size;
+
+   LTC_ARGCHK(prng   != NULL);
+   LTC_ARGCHK(out    != NULL);
+   LTC_ARGCHK(outlen != NULL);
+
+   if (*outlen < len) {
+      *outlen = len;
+      return CRYPT_BUFFER_OVERFLOW;
+   }
+
+   if (chacha20_prng_read(out, len, prng) != len) {
+      return CRYPT_ERROR_READPRNG;
+   }
+
+   *outlen = len;
+   return CRYPT_OK;
+}
+
+/**
+  Import a PRNG state
+  @param in       The PRNG state
+  @param inlen    Size of the state
+  @param prng     The PRNG to import
+  @return CRYPT_OK if successful
+*/
+int chacha20_prng_import(const unsigned char *in, unsigned long inlen, prng_state *prng)
+{
+   int err;
+
+   LTC_ARGCHK(prng != NULL);
+   LTC_ARGCHK(in   != NULL);
+   if (inlen < (unsigned long)chacha20_prng_desc.export_size) return CRYPT_INVALID_ARG;
+
+   if ((err = chacha20_prng_start(prng)) != CRYPT_OK)                  return err;
+   if ((err = chacha20_prng_add_entropy(in, inlen, prng)) != CRYPT_OK) return err;
+   return CRYPT_OK;
+}
+
+/**
+  PRNG self-test
+  @return CRYPT_OK if successful, CRYPT_NOP if self-testing has been disabled
+*/
+int chacha20_prng_test(void)
+{
+#ifndef LTC_TEST
+   return CRYPT_NOP;
+#else
+   prng_state st;
+   unsigned char en[] = { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a,
+                          0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14,
+                          0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e,
+                          0x1f, 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28,
+                          0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30, 0x31, 0x32 };
+   unsigned char dmp[300];
+   unsigned long dmplen = sizeof(dmp);
+   unsigned char out[500];
+   unsigned char t1[] = { 0x59, 0xB2, 0x26, 0x95, 0x2B, 0x01, 0x8F, 0x05, 0xBE, 0xD8 };
+   unsigned char t2[] = { 0x47, 0xC9, 0x0D, 0x03, 0xE4, 0x75, 0x34, 0x27, 0xBD, 0xDE };
+   unsigned char t3[] = { 0xBC, 0xFA, 0xEF, 0x59, 0x37, 0x7F, 0x1A, 0x91, 0x1A, 0xA6 };
+   int err;
+
+   if ((err = chacha20_prng_start(&st)) != CRYPT_OK)                       return err;
+   /* add entropy to uninitialized prng */
+   if ((err = chacha20_prng_add_entropy(en, sizeof(en), &st)) != CRYPT_OK) return err;
+   if ((err = chacha20_prng_ready(&st)) != CRYPT_OK)                       return err;
+   if (chacha20_prng_read(out, 10, &st) != 10)                             return CRYPT_ERROR_READPRNG; /* 10 bytes for testing */
+   if (compare_testvector(out, 10, t1, sizeof(t1), "CHACHA-PRNG", 1))      return CRYPT_FAIL_TESTVECTOR;
+   if (chacha20_prng_read(out, 500, &st) != 500)                           return CRYPT_ERROR_READPRNG; /* skip 500 bytes */
+   /* add entropy to already initialized prng */
+   if ((err = chacha20_prng_add_entropy(en, sizeof(en), &st)) != CRYPT_OK) return err;
+   if (chacha20_prng_read(out, 500, &st) != 500)                           return CRYPT_ERROR_READPRNG; /* skip 500 bytes */
+   if ((err = chacha20_prng_export(dmp, &dmplen, &st)) != CRYPT_OK)        return err;
+   if (chacha20_prng_read(out, 500, &st) != 500)                           return CRYPT_ERROR_READPRNG; /* skip 500 bytes */
+   if (chacha20_prng_read(out, 10, &st) != 10)                             return CRYPT_ERROR_READPRNG; /* 10 bytes for testing */
+   if (compare_testvector(out, 10, t2, sizeof(t2), "CHACHA-PRNG", 2))      return CRYPT_FAIL_TESTVECTOR;
+   if ((err = chacha20_prng_done(&st)) != CRYPT_OK)                        return err;
+   if ((err = chacha20_prng_import(dmp, dmplen, &st)) != CRYPT_OK)         return err;
+   if ((err = chacha20_prng_ready(&st)) != CRYPT_OK)                       return err;
+   if (chacha20_prng_read(out, 500, &st) != 500)                           return CRYPT_ERROR_READPRNG; /* skip 500 bytes */
+   if (chacha20_prng_read(out, 10, &st) != 10)                             return CRYPT_ERROR_READPRNG; /* 10 bytes for testing */
+   if (compare_testvector(out, 10, t3, sizeof(t3), "CHACHA-PRNG", 3))      return CRYPT_FAIL_TESTVECTOR;
+   if ((err = chacha20_prng_done(&st)) != CRYPT_OK)                        return err;
+
+   return CRYPT_OK;
+#endif
+}
+
+#endif
+
+/* ref:         $Format:%D$ */
+/* git commit:  $Format:%H$ */
+/* commit time: $Format:%ai$ */