Ticket #61: imported libsrtp into third_party directory (backported from srtp branch)
git-svn-id: https://svn.pjsip.org/repos/pjproject/trunk@1730 74dad513-b988-da41-8d7b-12977e46ad98
diff --git a/third_party/srtp/crypto/rng/ctr_prng.c b/third_party/srtp/crypto/rng/ctr_prng.c
new file mode 100644
index 0000000..ab76df3
--- /dev/null
+++ b/third_party/srtp/crypto/rng/ctr_prng.c
@@ -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);
+ 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;
+}