mirror of
https://github.com/Laupetin/OpenAssetTools.git
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248 lines
8.4 KiB
C
248 lines
8.4 KiB
C
/* LibTomCrypt, modular cryptographic library -- Tom St Denis
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*
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* LibTomCrypt is a library that provides various cryptographic
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* algorithms in a highly modular and flexible manner.
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*
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* The library is free for all purposes without any express
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* guarantee it works.
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*/
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/* the idea of re-keying loosely follows the approach used in:
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* http://bxr.su/OpenBSD/lib/libc/crypt/arc4random.c
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*/
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#include "tomcrypt.h"
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#ifdef LTC_CHACHA20_PRNG
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const struct ltc_prng_descriptor chacha20_prng_desc =
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{
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"chacha20",
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40,
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&chacha20_prng_start,
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&chacha20_prng_add_entropy,
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&chacha20_prng_ready,
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&chacha20_prng_read,
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&chacha20_prng_done,
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&chacha20_prng_export,
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&chacha20_prng_import,
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&chacha20_prng_test
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};
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/**
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Start the PRNG
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@param prng The PRNG state to initialize
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@return CRYPT_OK if successful
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*/
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int chacha20_prng_start(prng_state *prng)
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{
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LTC_ARGCHK(prng != NULL);
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prng->ready = 0;
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XMEMSET(&prng->chacha.ent, 0, sizeof(prng->chacha.ent));
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prng->chacha.idx = 0;
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LTC_MUTEX_INIT(&prng->lock)
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return CRYPT_OK;
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}
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/**
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Add entropy to the PRNG state
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@param in The data to add
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@param inlen Length of the data to add
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@param prng PRNG state to update
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@return CRYPT_OK if successful
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*/
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int chacha20_prng_add_entropy(const unsigned char *in, unsigned long inlen, prng_state *prng)
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{
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unsigned char buf[40];
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unsigned long i;
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int err;
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LTC_ARGCHK(prng != NULL);
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LTC_ARGCHK(in != NULL);
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LTC_ARGCHK(inlen > 0);
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LTC_MUTEX_LOCK(&prng->lock);
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if (prng->ready) {
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/* chacha20_prng_ready() was already called, do "rekey" operation */
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if ((err = chacha_keystream(&prng->chacha.s, buf, sizeof(buf))) != CRYPT_OK) goto LBL_UNLOCK;
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for(i = 0; i < inlen; i++) buf[i % sizeof(buf)] ^= in[i];
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/* key 32 bytes, 20 rounds */
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if ((err = chacha_setup(&prng->chacha.s, buf, 32, 20)) != CRYPT_OK) goto LBL_UNLOCK;
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/* iv 8 bytes */
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if ((err = chacha_ivctr64(&prng->chacha.s, buf + 32, 8, 0)) != CRYPT_OK) goto LBL_UNLOCK;
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/* clear KEY + IV */
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zeromem(buf, sizeof(buf));
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}
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else {
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/* chacha20_prng_ready() was not called yet, add entropy to ent buffer */
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while (inlen--) prng->chacha.ent[prng->chacha.idx++ % sizeof(prng->chacha.ent)] ^= *in++;
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}
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err = CRYPT_OK;
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LBL_UNLOCK:
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LTC_MUTEX_UNLOCK(&prng->lock);
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return err;
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}
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/**
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Make the PRNG ready to read from
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@param prng The PRNG to make active
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@return CRYPT_OK if successful
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*/
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int chacha20_prng_ready(prng_state *prng)
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{
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int err;
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LTC_ARGCHK(prng != NULL);
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LTC_MUTEX_LOCK(&prng->lock);
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if (prng->ready) { err = CRYPT_OK; goto LBL_UNLOCK; }
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/* key 32 bytes, 20 rounds */
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if ((err = chacha_setup(&prng->chacha.s, prng->chacha.ent, 32, 20)) != CRYPT_OK) goto LBL_UNLOCK;
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/* iv 8 bytes */
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if ((err = chacha_ivctr64(&prng->chacha.s, prng->chacha.ent + 32, 8, 0)) != CRYPT_OK) goto LBL_UNLOCK;
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XMEMSET(&prng->chacha.ent, 0, sizeof(prng->chacha.ent));
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prng->chacha.idx = 0;
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prng->ready = 1;
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LBL_UNLOCK:
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LTC_MUTEX_UNLOCK(&prng->lock);
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return err;
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}
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/**
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Read from the PRNG
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@param out Destination
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@param outlen Length of output
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@param prng The active PRNG to read from
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@return Number of octets read
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*/
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unsigned long chacha20_prng_read(unsigned char *out, unsigned long outlen, prng_state *prng)
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{
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if (outlen == 0 || prng == NULL || out == NULL) return 0;
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LTC_MUTEX_LOCK(&prng->lock);
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if (!prng->ready) { outlen = 0; goto LBL_UNLOCK; }
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if (chacha_keystream(&prng->chacha.s, out, outlen) != CRYPT_OK) outlen = 0;
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LBL_UNLOCK:
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LTC_MUTEX_UNLOCK(&prng->lock);
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return outlen;
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}
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/**
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Terminate the PRNG
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@param prng The PRNG to terminate
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@return CRYPT_OK if successful
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*/
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int chacha20_prng_done(prng_state *prng)
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{
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int err;
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LTC_ARGCHK(prng != NULL);
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LTC_MUTEX_LOCK(&prng->lock);
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prng->ready = 0;
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err = chacha_done(&prng->chacha.s);
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LTC_MUTEX_UNLOCK(&prng->lock);
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LTC_MUTEX_DESTROY(&prng->lock);
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return err;
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}
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/**
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Export the PRNG state
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@param out [out] Destination
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@param outlen [in/out] Max size and resulting size of the state
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@param prng The PRNG to export
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@return CRYPT_OK if successful
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*/
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int chacha20_prng_export(unsigned char *out, unsigned long *outlen, prng_state *prng)
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{
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unsigned long len = chacha20_prng_desc.export_size;
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LTC_ARGCHK(prng != NULL);
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LTC_ARGCHK(out != NULL);
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LTC_ARGCHK(outlen != NULL);
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if (*outlen < len) {
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*outlen = len;
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return CRYPT_BUFFER_OVERFLOW;
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}
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if (chacha20_prng_read(out, len, prng) != len) {
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return CRYPT_ERROR_READPRNG;
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}
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*outlen = len;
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return CRYPT_OK;
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}
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/**
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Import a PRNG state
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@param in The PRNG state
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@param inlen Size of the state
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@param prng The PRNG to import
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@return CRYPT_OK if successful
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*/
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int chacha20_prng_import(const unsigned char *in, unsigned long inlen, prng_state *prng)
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{
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int err;
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LTC_ARGCHK(prng != NULL);
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LTC_ARGCHK(in != NULL);
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if (inlen < (unsigned long)chacha20_prng_desc.export_size) return CRYPT_INVALID_ARG;
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if ((err = chacha20_prng_start(prng)) != CRYPT_OK) return err;
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if ((err = chacha20_prng_add_entropy(in, inlen, prng)) != CRYPT_OK) return err;
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return CRYPT_OK;
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}
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/**
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PRNG self-test
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@return CRYPT_OK if successful, CRYPT_NOP if self-testing has been disabled
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*/
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int chacha20_prng_test(void)
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{
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#ifndef LTC_TEST
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return CRYPT_NOP;
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#else
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prng_state st;
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unsigned char en[] = { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a,
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0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14,
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0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e,
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0x1f, 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28,
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0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30, 0x31, 0x32 };
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unsigned char dmp[300];
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unsigned long dmplen = sizeof(dmp);
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unsigned char out[500];
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unsigned char t1[] = { 0x59, 0xB2, 0x26, 0x95, 0x2B, 0x01, 0x8F, 0x05, 0xBE, 0xD8 };
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unsigned char t2[] = { 0x47, 0xC9, 0x0D, 0x03, 0xE4, 0x75, 0x34, 0x27, 0xBD, 0xDE };
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unsigned char t3[] = { 0xBC, 0xFA, 0xEF, 0x59, 0x37, 0x7F, 0x1A, 0x91, 0x1A, 0xA6 };
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int err;
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if ((err = chacha20_prng_start(&st)) != CRYPT_OK) return err;
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/* add entropy to uninitialized prng */
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if ((err = chacha20_prng_add_entropy(en, sizeof(en), &st)) != CRYPT_OK) return err;
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if ((err = chacha20_prng_ready(&st)) != CRYPT_OK) return err;
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if (chacha20_prng_read(out, 10, &st) != 10) return CRYPT_ERROR_READPRNG; /* 10 bytes for testing */
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if (compare_testvector(out, 10, t1, sizeof(t1), "CHACHA-PRNG", 1)) return CRYPT_FAIL_TESTVECTOR;
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if (chacha20_prng_read(out, 500, &st) != 500) return CRYPT_ERROR_READPRNG; /* skip 500 bytes */
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/* add entropy to already initialized prng */
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if ((err = chacha20_prng_add_entropy(en, sizeof(en), &st)) != CRYPT_OK) return err;
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if (chacha20_prng_read(out, 500, &st) != 500) return CRYPT_ERROR_READPRNG; /* skip 500 bytes */
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if ((err = chacha20_prng_export(dmp, &dmplen, &st)) != CRYPT_OK) return err;
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if (chacha20_prng_read(out, 500, &st) != 500) return CRYPT_ERROR_READPRNG; /* skip 500 bytes */
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if (chacha20_prng_read(out, 10, &st) != 10) return CRYPT_ERROR_READPRNG; /* 10 bytes for testing */
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if (compare_testvector(out, 10, t2, sizeof(t2), "CHACHA-PRNG", 2)) return CRYPT_FAIL_TESTVECTOR;
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if ((err = chacha20_prng_done(&st)) != CRYPT_OK) return err;
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if ((err = chacha20_prng_import(dmp, dmplen, &st)) != CRYPT_OK) return err;
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if ((err = chacha20_prng_ready(&st)) != CRYPT_OK) return err;
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if (chacha20_prng_read(out, 500, &st) != 500) return CRYPT_ERROR_READPRNG; /* skip 500 bytes */
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if (chacha20_prng_read(out, 10, &st) != 10) return CRYPT_ERROR_READPRNG; /* 10 bytes for testing */
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if (compare_testvector(out, 10, t3, sizeof(t3), "CHACHA-PRNG", 3)) return CRYPT_FAIL_TESTVECTOR;
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if ((err = chacha20_prng_done(&st)) != CRYPT_OK) return err;
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return CRYPT_OK;
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#endif
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}
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#endif
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/* ref: HEAD -> master, tag: v1.18.2 */
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/* git commit: 7e7eb695d581782f04b24dc444cbfde86af59853 */
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/* commit time: 2018-07-01 22:49:01 +0200 */
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