| // SPDX-License-Identifier: BSD-2-Clause |
| /* 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_private.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->u.chacha.ent, 0, sizeof(prng->u.chacha.ent)); |
| prng->u.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->u.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->u.chacha.s, buf, 32, 20)) != CRYPT_OK) goto LBL_UNLOCK; |
| /* iv 8 bytes */ |
| if ((err = chacha_ivctr64(&prng->u.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->u.chacha.ent[prng->u.chacha.idx++ % sizeof(prng->u.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->u.chacha.s, prng->u.chacha.ent, 32, 20)) != CRYPT_OK) goto LBL_UNLOCK; |
| /* iv 8 bytes */ |
| if ((err = chacha_ivctr64(&prng->u.chacha.s, prng->u.chacha.ent + 32, 8, 0)) != CRYPT_OK) goto LBL_UNLOCK; |
| XMEMSET(&prng->u.chacha.ent, 0, sizeof(prng->u.chacha.ent)); |
| prng->u.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->u.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->u.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 |
| */ |
| _LTC_PRNG_EXPORT(chacha20_prng) |
| |
| /** |
| 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: $Format:%ai$ */ |
