--- /dev/null
+/* 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: $Format:%ai$ */
projects / zpackage / blobdiff