| // 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. |
| */ |
| #include "tomcrypt_private.h" |
| |
| /** |
| @file prngs/rc4.c |
| RC4 PRNG, Tom St Denis |
| */ |
| |
| #ifdef LTC_RC4 |
| |
| const struct ltc_prng_descriptor rc4_desc = |
| { |
| "rc4", |
| 32, |
| &rc4_start, |
| &rc4_add_entropy, |
| &rc4_ready, |
| &rc4_read, |
| &rc4_done, |
| &rc4_export, |
| &rc4_import, |
| &rc4_test |
| }; |
| |
| /** |
| Start the PRNG |
| @param prng [out] The PRNG state to initialize |
| @return CRYPT_OK if successful |
| */ |
| int rc4_start(prng_state *prng) |
| { |
| LTC_ARGCHK(prng != NULL); |
| prng->ready = 0; |
| /* set entropy (key) size to zero */ |
| prng->u.rc4.s.x = 0; |
| /* clear entropy (key) buffer */ |
| XMEMSET(&prng->u.rc4.s.buf, 0, sizeof(prng->u.rc4.s.buf)); |
| 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 rc4_add_entropy(const unsigned char *in, unsigned long inlen, prng_state *prng) |
| { |
| unsigned char buf[256]; |
| 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) { |
| /* rc4_ready() was already called, do "rekey" operation */ |
| if ((err = rc4_stream_keystream(&prng->u.rc4.s, buf, sizeof(buf))) != CRYPT_OK) goto LBL_UNLOCK; |
| for(i = 0; i < inlen; i++) buf[i % sizeof(buf)] ^= in[i]; |
| /* initialize RC4 */ |
| if ((err = rc4_stream_setup(&prng->u.rc4.s, buf, sizeof(buf))) != CRYPT_OK) goto LBL_UNLOCK; |
| /* drop first 3072 bytes - https://en.wikipedia.org/wiki/RC4#Fluhrer.2C_Mantin_and_Shamir_attack */ |
| for (i = 0; i < 12; i++) rc4_stream_keystream(&prng->u.rc4.s, buf, sizeof(buf)); |
| zeromem(buf, sizeof(buf)); |
| } |
| else { |
| /* rc4_ready() was not called yet, add entropy to the buffer */ |
| while (inlen--) prng->u.rc4.s.buf[prng->u.rc4.s.x++ % sizeof(prng->u.rc4.s.buf)] ^= *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 rc4_ready(prng_state *prng) |
| { |
| unsigned char buf[256] = { 0 }; |
| unsigned long len; |
| int err, i; |
| |
| LTC_ARGCHK(prng != NULL); |
| |
| LTC_MUTEX_LOCK(&prng->lock); |
| if (prng->ready) { err = CRYPT_OK; goto LBL_UNLOCK; } |
| XMEMCPY(buf, prng->u.rc4.s.buf, sizeof(buf)); |
| /* initialize RC4 */ |
| len = MIN(prng->u.rc4.s.x, 256); /* TODO: we can perhaps always use all 256 bytes */ |
| if ((err = rc4_stream_setup(&prng->u.rc4.s, buf, len)) != CRYPT_OK) goto LBL_UNLOCK; |
| /* drop first 3072 bytes - https://en.wikipedia.org/wiki/RC4#Fluhrer.2C_Mantin_and_Shamir_attack */ |
| for (i = 0; i < 12; i++) rc4_stream_keystream(&prng->u.rc4.s, buf, sizeof(buf)); |
| 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 rc4_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 (rc4_stream_keystream(&prng->u.rc4.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 rc4_done(prng_state *prng) |
| { |
| int err; |
| LTC_ARGCHK(prng != NULL); |
| LTC_MUTEX_LOCK(&prng->lock); |
| prng->ready = 0; |
| err = rc4_stream_done(&prng->u.rc4.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(rc4) |
| |
| /** |
| 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 rc4_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)rc4_desc.export_size) return CRYPT_INVALID_ARG; |
| |
| if ((err = rc4_start(prng)) != CRYPT_OK) return err; |
| if ((err = rc4_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 rc4_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[500]; |
| unsigned long dmplen = sizeof(dmp); |
| unsigned char out[1000]; |
| unsigned char t1[] = { 0xE0, 0x4D, 0x9A, 0xF6, 0xA8, 0x9D, 0x77, 0x53, 0xAE, 0x09 }; |
| unsigned char t2[] = { 0xEF, 0x80, 0xA2, 0xE6, 0x50, 0x91, 0xF3, 0x17, 0x4A, 0x8A }; |
| unsigned char t3[] = { 0x4B, 0xD6, 0x5C, 0x67, 0x99, 0x03, 0x56, 0x12, 0x80, 0x48 }; |
| int err; |
| |
| if ((err = rc4_start(&st)) != CRYPT_OK) return err; |
| /* add entropy to uninitialized prng */ |
| if ((err = rc4_add_entropy(en, sizeof(en), &st)) != CRYPT_OK) return err; |
| if ((err = rc4_ready(&st)) != CRYPT_OK) return err; |
| if (rc4_read(out, 10, &st) != 10) return CRYPT_ERROR_READPRNG; /* 10 bytes for testing */ |
| if (compare_testvector(out, 10, t1, sizeof(t1), "RC4-PRNG", 1)) return CRYPT_FAIL_TESTVECTOR; |
| if (rc4_read(out, 500, &st) != 500) return CRYPT_ERROR_READPRNG; /* skip 500 bytes */ |
| /* add entropy to already initialized prng */ |
| if ((err = rc4_add_entropy(en, sizeof(en), &st)) != CRYPT_OK) return err; |
| if (rc4_read(out, 500, &st) != 500) return CRYPT_ERROR_READPRNG; /* skip 500 bytes */ |
| if ((err = rc4_export(dmp, &dmplen, &st)) != CRYPT_OK) return err; |
| if (rc4_read(out, 500, &st) != 500) return CRYPT_ERROR_READPRNG; /* skip 500 bytes */ |
| if (rc4_read(out, 10, &st) != 10) return CRYPT_ERROR_READPRNG; /* 10 bytes for testing */ |
| if (compare_testvector(out, 10, t2, sizeof(t2), "RC4-PRNG", 2)) return CRYPT_FAIL_TESTVECTOR; |
| if ((err = rc4_done(&st)) != CRYPT_OK) return err; |
| if ((err = rc4_import(dmp, dmplen, &st)) != CRYPT_OK) return err; |
| if ((err = rc4_ready(&st)) != CRYPT_OK) return err; |
| if (rc4_read(out, 500, &st) != 500) return CRYPT_ERROR_READPRNG; /* skip 500 bytes */ |
| if (rc4_read(out, 10, &st) != 10) return CRYPT_ERROR_READPRNG; /* 10 bytes for testing */ |
| if (compare_testvector(out, 10, t3, sizeof(t3), "RC4-PRNG", 3)) return CRYPT_FAIL_TESTVECTOR; |
| if ((err = rc4_done(&st)) != CRYPT_OK) return err; |
| |
| return CRYPT_OK; |
| #endif |
| } |
| |
| #endif |
| |
| /* ref: $Format:%D$ */ |
| /* git commit: $Format:%H$ */ |
| /* commit time: $Format:%ai$ */ |