ext: Pull in tinycrypt v0.2.6

Zephyr 1.9 moves to tinycrypt v0.2.7.  This introduces a breaking API
change.  This makes things challenging for mcuboot, which would like to
be able to work across multiple platforms.

To help with this, bring in the last working version of Tinycrypt v0.2.6
from https://github.com/01org/tinycrypt.  Tinycrypt is released under a
3-clause BSD-style license, with parts under the micro-ecc license,
which is a 2-clause license.  Please see ext/tinycrypt/LICENSE for
details.

Signed-off-by: David Brown <david.brown@linaro.org>
diff --git a/ext/tinycrypt/lib/source/cbc_mode.c b/ext/tinycrypt/lib/source/cbc_mode.c
new file mode 100644
index 0000000..8163e0d
--- /dev/null
+++ b/ext/tinycrypt/lib/source/cbc_mode.c
@@ -0,0 +1,113 @@
+/* cbc_mode.c - TinyCrypt implementation of CBC mode encryption & decryption */
+
+/*
+ *  Copyright (C) 2015 by Intel Corporation, 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 Intel Corporation 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 OWNER 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 <tinycrypt/cbc_mode.h>
+#include <tinycrypt/constants.h>
+#include <tinycrypt/utils.h>
+
+int32_t tc_cbc_mode_encrypt(uint8_t *out, uint32_t outlen, const uint8_t *in,
+			    uint32_t inlen, const uint8_t *iv,
+			    const TCAesKeySched_t sched)
+{
+
+	uint8_t buffer[TC_AES_BLOCK_SIZE];
+	uint32_t n, m;
+
+	/* input sanity check: */
+	if (out == (uint8_t *) 0 ||
+	    in == (const uint8_t *) 0 ||
+	    sched == (TCAesKeySched_t) 0 ||
+	    inlen == 0 ||
+	    outlen == 0 ||
+	    (inlen % TC_AES_BLOCK_SIZE) != 0 ||
+	    (outlen % TC_AES_BLOCK_SIZE) != 0 ||
+	    outlen != inlen + TC_AES_BLOCK_SIZE) {
+		return TC_CRYPTO_FAIL;
+	}
+
+	/* copy iv to the buffer */
+	(void)_copy(buffer, TC_AES_BLOCK_SIZE, iv, TC_AES_BLOCK_SIZE);
+	/* copy iv to the output buffer */
+	(void)_copy(out, TC_AES_BLOCK_SIZE, iv, TC_AES_BLOCK_SIZE);
+	out += TC_AES_BLOCK_SIZE;
+
+	for (n = m = 0; n < inlen; ++n) {
+		buffer[m++] ^= *in++;
+		if (m == TC_AES_BLOCK_SIZE) {
+			(void)tc_aes_encrypt(buffer, buffer, sched);
+			(void)_copy(out, TC_AES_BLOCK_SIZE,
+				    buffer, TC_AES_BLOCK_SIZE);
+			out += TC_AES_BLOCK_SIZE;
+			m = 0;
+		}
+	}
+
+	return TC_CRYPTO_SUCCESS;
+}
+
+int32_t tc_cbc_mode_decrypt(uint8_t *out, uint32_t outlen, const uint8_t *in,
+			    uint32_t inlen, const uint8_t *iv,
+			    const TCAesKeySched_t sched)
+{
+	uint8_t buffer[TC_AES_BLOCK_SIZE];
+	const uint8_t *p;
+	uint32_t n, m;
+
+	/* sanity check the inputs */
+	if (out == (uint8_t *) 0 ||
+	    in == (const uint8_t *) 0 ||
+	    sched == (TCAesKeySched_t) 0 ||
+	    inlen == 0 ||
+	    outlen == 0 ||
+	    (inlen % TC_AES_BLOCK_SIZE) != 0 ||
+	    (outlen % TC_AES_BLOCK_SIZE) != 0 ||
+	    outlen != inlen - TC_AES_BLOCK_SIZE) {
+		return TC_CRYPTO_FAIL;
+	}
+
+	/*
+	 * Note that in == iv + ciphertext, i.e. the iv and the ciphertext are
+	 * contiguous. This allows for a very efficient decryption algorithm
+	 * that would not otherwise be possible.
+	 */
+	p = iv;
+	for (n = m = 0; n < inlen; ++n) {
+		if ((n % TC_AES_BLOCK_SIZE) == 0) {
+			(void)tc_aes_decrypt(buffer, in, sched);
+			in += TC_AES_BLOCK_SIZE;
+			m = 0;
+		}
+		*out++ = buffer[m++] ^ *p++;
+	}
+
+	return TC_CRYPTO_SUCCESS;
+}