1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis */ 2 /* SPDX-License-Identifier: Unlicense */ 3 #include "tomcrypt_private.h" 4 5 /** 6 @file sprng.c 7 Secure PRNG, Tom St Denis 8 */ 9 10 /* A secure PRNG using the RNG functions. Basically this is a 11 * wrapper that allows you to use a secure RNG as a PRNG 12 * in the various other functions. 13 */ 14 15 #ifdef LTC_SPRNG 16 17 const struct ltc_prng_descriptor sprng_desc = 18 { 19 "sprng", 0, 20 &sprng_start, 21 &sprng_add_entropy, 22 &sprng_ready, 23 &sprng_read, 24 &sprng_done, 25 &sprng_export, 26 &sprng_import, 27 &sprng_test 28 }; 29 30 /** 31 Start the PRNG 32 @param prng [out] The PRNG state to initialize 33 @return CRYPT_OK if successful 34 */ 35 int sprng_start(prng_state *prng) 36 { 37 LTC_UNUSED_PARAM(prng); 38 return CRYPT_OK; 39 } 40 41 /** 42 Add entropy to the PRNG state 43 @param in The data to add 44 @param inlen Length of the data to add 45 @param prng PRNG state to update 46 @return CRYPT_OK if successful 47 */ 48 int sprng_add_entropy(const unsigned char *in, unsigned long inlen, prng_state *prng) 49 { 50 LTC_UNUSED_PARAM(in); 51 LTC_UNUSED_PARAM(inlen); 52 LTC_UNUSED_PARAM(prng); 53 return CRYPT_OK; 54 } 55 56 /** 57 Make the PRNG ready to read from 58 @param prng The PRNG to make active 59 @return CRYPT_OK if successful 60 */ 61 int sprng_ready(prng_state *prng) 62 { 63 LTC_UNUSED_PARAM(prng); 64 return CRYPT_OK; 65 } 66 67 /** 68 Read from the PRNG 69 @param out Destination 70 @param outlen Length of output 71 @param prng The active PRNG to read from 72 @return Number of octets read 73 */ 74 unsigned long sprng_read(unsigned char *out, unsigned long outlen, prng_state *prng) 75 { 76 LTC_ARGCHK(out != NULL); 77 LTC_UNUSED_PARAM(prng); 78 return rng_get_bytes(out, outlen, NULL); 79 } 80 81 /** 82 Terminate the PRNG 83 @param prng The PRNG to terminate 84 @return CRYPT_OK if successful 85 */ 86 int sprng_done(prng_state *prng) 87 { 88 LTC_UNUSED_PARAM(prng); 89 return CRYPT_OK; 90 } 91 92 /** 93 Export the PRNG state 94 @param out [out] Destination 95 @param outlen [in/out] Max size and resulting size of the state 96 @param prng The PRNG to export 97 @return CRYPT_OK if successful 98 */ 99 /* NOLINTNEXTLINE(readability-non-const-parameter) - silence clang-tidy warning */ 100 int sprng_export(unsigned char *out, unsigned long *outlen, prng_state *prng) 101 { 102 LTC_ARGCHK(outlen != NULL); 103 LTC_UNUSED_PARAM(out); 104 LTC_UNUSED_PARAM(prng); 105 106 *outlen = 0; 107 return CRYPT_OK; 108 } 109 110 /** 111 Import a PRNG state 112 @param in The PRNG state 113 @param inlen Size of the state 114 @param prng The PRNG to import 115 @return CRYPT_OK if successful 116 */ 117 int sprng_import(const unsigned char *in, unsigned long inlen, prng_state *prng) 118 { 119 LTC_UNUSED_PARAM(in); 120 LTC_UNUSED_PARAM(inlen); 121 LTC_UNUSED_PARAM(prng); 122 return CRYPT_OK; 123 } 124 125 /** 126 PRNG self-test 127 @return CRYPT_OK if successful, CRYPT_NOP if self-testing has been disabled 128 */ 129 int sprng_test(void) 130 { 131 #ifndef LTC_TEST 132 return CRYPT_NOP; 133 #else 134 prng_state st; 135 unsigned char en[] = { 0x01, 0x02, 0x03, 0x04 }; 136 unsigned char out[1000]; 137 int err; 138 139 if ((err = sprng_start(&st)) != CRYPT_OK) return err; 140 if ((err = sprng_add_entropy(en, sizeof(en), &st)) != CRYPT_OK) return err; 141 if ((err = sprng_ready(&st)) != CRYPT_OK) return err; 142 if (sprng_read(out, 500, &st) != 500) return CRYPT_ERROR_READPRNG; /* skip 500 bytes */ 143 if ((err = sprng_done(&st)) != CRYPT_OK) return err; 144 145 return CRYPT_OK; 146 #endif 147 } 148 149 #endif 150 151 152 153