Index: libsrtp/crypto/rng/ctr_prng.c |
=================================================================== |
--- libsrtp/crypto/rng/ctr_prng.c (revision 0) |
+++ libsrtp/crypto/rng/ctr_prng.c (revision 0) |
@@ -0,0 +1,108 @@ |
+/* |
+ * ctr_prng.c |
+ * |
+ * counter mode based pseudorandom source |
+ * |
+ * David A. McGrew |
+ * Cisco Systems, Inc. |
+ */ |
+/* |
+ * |
+ * Copyright(c) 2001-2006 Cisco Systems, Inc. |
+ * All rights reserved. |
+ * |
+ * Redistribution and use in source and binary forms, with or without |
+ * modification, are permitted provided that the following conditions |
+ * are met: |
+ * |
+ * Redistributions of source code must retain the above copyright |
+ * notice, this list of conditions and the following disclaimer. |
+ * |
+ * Redistributions in binary form must reproduce the above |
+ * copyright notice, this list of conditions and the following |
+ * disclaimer in the documentation and/or other materials provided |
+ * with the distribution. |
+ * |
+ * Neither the name of the Cisco Systems, Inc. nor the names of its |
+ * contributors may be used to endorse or promote products derived |
+ * from this software without specific prior written permission. |
+ * |
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
+ * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, |
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES |
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR |
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED |
+ * OF THE POSSIBILITY OF SUCH DAMAGE. |
+ * |
+ */ |
+ |
+ |
+#include "prng.h" |
+ |
+/* single, global prng structure */ |
+ |
+ctr_prng_t ctr_prng; |
+ |
+err_status_t |
+ctr_prng_init(rand_source_func_t random_source) { |
+ uint8_t tmp_key[32]; |
+ err_status_t status; |
+ |
+ /* initialize output count to zero */ |
+ ctr_prng.octet_count = 0; |
+ |
+ /* set random source */ |
+ ctr_prng.rand = random_source; |
+ |
+ /* initialize secret key from random source */ |
+ status = random_source(tmp_key, 32); |
+ if (status) |
+ return status; |
+ |
+ /* initialize aes ctr context with random key */ |
+ status = aes_icm_context_init(&ctr_prng.state, tmp_key, 30); |
+ if (status) |
+ return status; |
+ |
+ return err_status_ok; |
+} |
+ |
+err_status_t |
+ctr_prng_get_octet_string(void *dest, uint32_t len) { |
+ err_status_t status; |
+ |
+ /* |
+ * if we need to re-initialize the prng, do so now |
+ * |
+ * avoid 32-bit overflows by subtracting instead of adding |
+ */ |
+ if (ctr_prng.octet_count > MAX_PRNG_OUT_LEN - len) { |
+ status = ctr_prng_init(ctr_prng.rand); |
+ if (status) |
+ return status; |
+ } |
+ ctr_prng.octet_count += len; |
+ |
+ /* |
+ * write prng output |
+ */ |
+ status = aes_icm_output(&ctr_prng.state, (uint8_t*)dest, len); |
+ if (status) |
+ return status; |
+ |
+ return err_status_ok; |
+} |
+ |
+err_status_t |
+ctr_prng_deinit(void) { |
+ |
+ /* nothing */ |
+ |
+ return err_status_ok; |
+} |
Property changes on: libsrtp/crypto/rng/ctr_prng.c |
___________________________________________________________________ |
Added: svn:eol-style |
+ LF |