Mercurial > dropbear
view libtomcrypt/src/prngs/rc4.c @ 1633:592a18dac250
Support servers without multiple user support (#76)
author | Patrick Stewart <patstew@gmail.com> |
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date | Wed, 20 Mar 2019 14:44:49 +0000 |
parents | 6dba84798cd5 |
children |
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/* 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.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->rc4.s.x = 0; /* clear entropy (key) buffer */ XMEMSET(&prng->rc4.s.buf, 0, sizeof(prng->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->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->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->rc4.s, buf, sizeof(buf)); zeromem(buf, sizeof(buf)); } else { /* rc4_ready() was not called yet, add entropy to the buffer */ while (inlen--) prng->rc4.s.buf[prng->rc4.s.x++ % sizeof(prng->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->rc4.s.buf, sizeof(buf)); /* initialize RC4 */ len = MIN(prng->rc4.s.x, 256); /* TODO: we can perhaps always use all 256 bytes */ if ((err = rc4_stream_setup(&prng->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->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->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->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 */ int rc4_export(unsigned char *out, unsigned long *outlen, prng_state *prng) { unsigned long len = rc4_desc.export_size; LTC_ARGCHK(prng != NULL); LTC_ARGCHK(out != NULL); LTC_ARGCHK(outlen != NULL); if (*outlen < len) { *outlen = len; return CRYPT_BUFFER_OVERFLOW; } if (rc4_read(out, len, prng) != len) { return CRYPT_ERROR_READPRNG; } *outlen = len; return CRYPT_OK; } /** 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: $Format:%ai$ */