/* 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. * * Tom St Denis, tomstdenis@iahu.ca, http://libtomcrypt.org */#include "mycrypt.h"/* v1.5 Encryption Padding for PKCS #1 -- Tom St Denis */#ifdef PKCS_1int pkcs_1_v15_es_encode(const unsigned char *msg,    unsigned long msglen,                               unsigned long  modulus_bitlen,                                prng_state    *prng,   int           prng_idx,                               unsigned char *out,    unsigned long *outlen){    unsigned long modulus_bytelen, x, y;   _ARGCHK(msg    != NULL);   _ARGCHK(out    != NULL);   _ARGCHK(outlen != NULL);   /* get modulus len */   modulus_bytelen = (modulus_bitlen >> 3) + (modulus_bitlen & 7 ? 1 : 0);   if (modulus_bytelen < 12) {      return CRYPT_INVALID_ARG;   }   /* verify length */   if (msglen > (modulus_bytelen - 11) || *outlen < modulus_bytelen) {      return CRYPT_PK_INVALID_SIZE;   }   /* 0x00 0x02 PS 0x00 M */   x = 0;   out[x++] = 0x00;   out[x++] = 0x02;   y = modulus_bytelen - msglen - 3;   if (prng_descriptor[prng_idx].read(out+x, y, prng) != y) {      return CRYPT_ERROR_READPRNG;   }   x += y;   out[x++] = 0x00;   memcpy(out+x, msg, msglen);   *outlen = modulus_bytelen;   return CRYPT_OK;}#endif /* PKCS_1 */