1 files changed, 116 insertions, 0 deletions

diff --git a/src/lib/libcrypto/hkdf/hkdf.c b/src/lib/libcrypto/hkdf/hkdf.c
new file mode 100644
index 0000000000..9fe587de13
--- /dev/null
+++ b/src/lib/libcrypto/hkdf/hkdf.c
@@ -0,0 +1,116 @@
+/* Copyright (c) 2014, Google Inc.
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+ * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <openssl/hkdf.h>
+
+#include <assert.h>
+#include <string.h>
+
+#include <openssl/err.h>
+#include <openssl/hmac.h>
+
+/* https://tools.ietf.org/html/rfc5869#section-2 */
+int
+HKDF(uint8_t *out_key, size_t out_len, const EVP_MD *digest,
+    const uint8_t *secret, size_t secret_len, const uint8_t *salt,
+    size_t salt_len, const uint8_t *info, size_t info_len)
+{
+        uint8_t prk[EVP_MAX_MD_SIZE];
+        size_t prk_len;
+
+        if (!HKDF_extract(prk, &prk_len, digest, secret, secret_len, salt,
+                salt_len))
+                return 0;
+        if (!HKDF_expand(out_key, out_len, digest, prk, prk_len, info,
+                info_len))
+                return 0;
+
+        return 1;
+}
+
+/* https://tools.ietf.org/html/rfc5869#section-2.2 */
+int
+HKDF_extract(uint8_t *out_key, size_t *out_len,
+    const EVP_MD *digest, const uint8_t *secret, size_t secret_len,
+    const uint8_t *salt, size_t salt_len)
+{
+        unsigned int len;
+
+        /*
+         * If salt is not given, HashLength zeros are used. However, HMAC does that
+         * internally already so we can ignore it.
+         */
+        if (HMAC(digest, salt, salt_len, secret, secret_len, out_key, &len) ==
+            NULL) {
+                CRYPTOerror(ERR_R_CRYPTO_LIB);
+                return 0;
+        }
+        *out_len = len;
+        return 1;
+}
+
+/* https://tools.ietf.org/html/rfc5869#section-2.3 */
+int
+HKDF_expand(uint8_t *out_key, size_t out_len,
+    const EVP_MD *digest, const uint8_t *prk, size_t prk_len,
+    const uint8_t *info, size_t info_len)
+{
+        const size_t digest_len = EVP_MD_size(digest);
+        uint8_t previous[EVP_MAX_MD_SIZE];
+        size_t n, done = 0;
+        unsigned int i;
+        int ret = 0;
+        HMAC_CTX hmac;
+
+        /* Expand key material to desired length. */
+        n = (out_len + digest_len - 1) / digest_len;
+        if (out_len + digest_len < out_len || n > 255) {
+                CRYPTOerror(EVP_R_TOO_LARGE);
+                return 0;
+        }
+
+        HMAC_CTX_init(&hmac);
+        if (!HMAC_Init_ex(&hmac, prk, prk_len, digest, NULL))
+                goto out;
+
+        for (i = 0; i < n; i++) {
+                uint8_t ctr = i + 1;
+                size_t todo;
+
+                if (i != 0 && (!HMAC_Init_ex(&hmac, NULL, 0, NULL, NULL) ||
+                        !HMAC_Update(&hmac, previous, digest_len)))
+                        goto out;
+
+                if (!HMAC_Update(&hmac, info, info_len) ||
+                    !HMAC_Update(&hmac, &ctr, 1) ||
+                    !HMAC_Final(&hmac, previous, NULL))
+                        goto out;
+
+                todo = digest_len;
+                if (done + todo > out_len)
+                        todo = out_len - done;
+
+                memcpy(out_key + done, previous, todo);
+                done += todo;
+        }
+
+        ret = 1;
+
+ out:
+        HMAC_CTX_cleanup(&hmac);
+        if (ret != 1)
+                CRYPTOerror(ERR_R_CRYPTO_LIB);
+        return ret;
+}