From 542861816d8305afa113653a84073be2fca68e50 Mon Sep 17 00:00:00 2001 From: Matthias Schiffer Date: Thu, 31 Oct 2013 23:11:00 +0100 Subject: Implement HKDF --- src/hkdf_sha256.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+) create mode 100644 src/hkdf_sha256.c (limited to 'src/hkdf_sha256.c') diff --git a/src/hkdf_sha256.c b/src/hkdf_sha256.c new file mode 100644 index 0000000..a85f5e3 --- /dev/null +++ b/src/hkdf_sha256.c @@ -0,0 +1,53 @@ +/* + Copyright (c) 2012-2013, Matthias Schiffer + All rights reserved. + + Redistribution and use in source and binary forms, with or without + modification, are permitted provided that the following conditions are met: + + 1. Redistributions of source code must retain the above copyright notice, + this list of conditions and the following disclaimer. + 2. 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. + + 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 HOLDER 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 "hkdf_sha256.h" + +#include + + +void fastd_hkdf_sha256_expand(fastd_sha256_t *out, size_t blocks, fastd_sha256_t *prk, const uint8_t *info, size_t infolen) { + if (!blocks) + return; + + size_t len = sizeof(fastd_sha256_t) + infolen + 1; + + uint8_t buf[len] __attribute__((align(4))); + + memset(buf, 0, sizeof(fastd_sha256_t)); + memcpy(buf+sizeof(fastd_sha256_t), info, infolen); + buf[len-1] = 0x01; + + fastd_hmacsha256(out, prk->w, (uint32_t*)(buf+sizeof(fastd_sha256_t)), infolen + 1); + + while (--blocks) { + memcpy(buf, out, sizeof(fastd_sha256_t)); + out++; + buf[len-1]++; + + fastd_hmacsha256(out, prk->w, (uint32_t*)buf, len); + } +} -- cgit v1.2.3