diff --git a/crypto/CMakeLists.txt b/crypto/CMakeLists.txt
index a42d92d..56b6616 100644
--- a/crypto/CMakeLists.txt
+++ b/crypto/CMakeLists.txt
@@ -105,6 +105,7 @@
 
 # Level 3
 add_subdirectory(evp)
+add_subdirectory(hkdf)
 add_subdirectory(pem)
 add_subdirectory(x509)
 add_subdirectory(x509v3)
@@ -160,6 +161,7 @@
 	$<TARGET_OBJECTS:ecdsa>
 	$<TARGET_OBJECTS:hmac>
 	$<TARGET_OBJECTS:evp>
+	$<TARGET_OBJECTS:hkdf>
 	$<TARGET_OBJECTS:pem>
 	$<TARGET_OBJECTS:x509>
 	$<TARGET_OBJECTS:x509v3>
diff --git a/crypto/err/err.c b/crypto/err/err.c
index 6349a74..4e63e21 100644
--- a/crypto/err/err.c
+++ b/crypto/err/err.c
@@ -678,6 +678,7 @@
     "Digest functions",                           /* ERR_LIB_DIGEST */
     "Cipher functions",                           /* ERR_LIB_CIPHER */
     "User defined functions",                     /* ERR_LIB_USER */
+    "HKDF functions",                             /* ERR_LIB_HKDF */
 };
 
 #define NUM_SYS_ERRNOS 127
@@ -722,6 +723,7 @@
 extern const ERR_STRING_DATA EC_error_string_data[];
 extern const ERR_STRING_DATA ENGINE_error_string_data[];
 extern const ERR_STRING_DATA EVP_error_string_data[];
+extern const ERR_STRING_DATA HKDF_error_string_data[];
 extern const ERR_STRING_DATA OBJ_error_string_data[];
 extern const ERR_STRING_DATA PEM_error_string_data[];
 extern const ERR_STRING_DATA PKCS8_error_string_data[];
@@ -776,6 +778,7 @@
   ERR_load_strings(EC_error_string_data);
   ERR_load_strings(ENGINE_error_string_data);
   ERR_load_strings(EVP_error_string_data);
+  ERR_load_strings(HKDF_error_string_data);
   ERR_load_strings(OBJ_error_string_data);
   ERR_load_strings(PEM_error_string_data);
   ERR_load_strings(PKCS8_error_string_data);
diff --git a/crypto/hkdf/CMakeLists.txt b/crypto/hkdf/CMakeLists.txt
new file mode 100644
index 0000000..1189883
--- /dev/null
+++ b/crypto/hkdf/CMakeLists.txt
@@ -0,0 +1,18 @@
+include_directories(. .. ../../include)
+
+add_library(
+	hkdf
+
+	OBJECT
+
+	hkdf.c
+	hkdf_error.c
+)
+
+add_executable(
+	hkdf_test
+
+	hkdf_test.c
+)
+
+target_link_libraries(hkdf_test crypto)
diff --git a/crypto/hkdf/hkdf.c b/crypto/hkdf/hkdf.c
new file mode 100644
index 0000000..be51bc3
--- /dev/null
+++ b/crypto/hkdf/hkdf.c
@@ -0,0 +1,88 @@
+/* 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 <openssl/err.h>
+#include <openssl/hmac.h>
+
+
+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) {
+  /* https://tools.ietf.org/html/rfc5869#section-2.2 */
+  const size_t digest_len = EVP_MD_size(digest);
+  uint8_t prk[EVP_MAX_MD_SIZE], previous[EVP_MAX_MD_SIZE];
+  size_t n, done = 0;
+  unsigned i, prk_len;
+  int ret = 0;
+  HMAC_CTX hmac;
+
+  /* If salt is not given, HashLength zeros are used. However, HMAC does that
+   * internally already so we can ignore it.*/
+
+  /* Expand key material to desired length. */
+  n = (out_len + digest_len - 1) / digest_len;
+  if (out_len + digest_len < out_len || n > 255) {
+    OPENSSL_PUT_ERROR(HKDF, HKDF, HKDF_R_OUTPUT_TOO_LARGE);
+    return 0;
+  }
+
+  HMAC_CTX_init(&hmac);
+
+  /* Extract input keying material into pseudorandom key |prk|. */
+  if (HMAC(digest, salt, salt_len, secret, secret_len, prk, &prk_len) == NULL) {
+    goto out;
+  }
+  assert(prk_len == digest_len);
+
+  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) {
+    OPENSSL_PUT_ERROR(HKDF, HKDF, ERR_R_HMAC_LIB);
+  }
+  return ret;
+}
diff --git a/crypto/hkdf/hkdf_error.c b/crypto/hkdf/hkdf_error.c
new file mode 100644
index 0000000..e1928d6
--- /dev/null
+++ b/crypto/hkdf/hkdf_error.c
@@ -0,0 +1,23 @@
+/* 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/err.h>
+
+#include <openssl/hkdf.h>
+
+const ERR_STRING_DATA HKDF_error_string_data[] = {
+  {ERR_PACK(ERR_LIB_HKDF, HKDF_F_HKDF, 0), "HKDF"},
+  {ERR_PACK(ERR_LIB_HKDF, 0, HKDF_R_OUTPUT_TOO_LARGE), "OUTPUT_TOO_LARGE"},
+  {0, NULL},
+};
diff --git a/crypto/hkdf/hkdf_test.c b/crypto/hkdf/hkdf_test.c
new file mode 100644
index 0000000..5e424a6
--- /dev/null
+++ b/crypto/hkdf/hkdf_test.c
@@ -0,0 +1,233 @@
+/* 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 <stdio.h>
+
+#include <openssl/bio.h>
+#include <openssl/crypto.h>
+#include <openssl/digest.h>
+#include <openssl/err.h>
+#include <openssl/hkdf.h>
+
+
+typedef struct {
+  const EVP_MD *(*md_func)(void);
+  const uint8_t ikm[80];
+  const size_t ikm_len;
+  const uint8_t salt[80];
+  const size_t salt_len;
+  const uint8_t info[80];
+  const size_t info_len;
+  const size_t out_len;
+  const uint8_t out[82];
+} hkdf_test_vector_t;
+
+/* These test vectors are from RFC 5869. */
+static const hkdf_test_vector_t kTests[] = {
+  {
+    EVP_sha256,
+    {
+      0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
+      0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
+    }, 22,
+    {
+      0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b,
+      0x0c,
+    }, 13,
+    {
+      0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8, 0xf9,
+    }, 10,
+    42, {
+      0x3c, 0xb2, 0x5f, 0x25, 0xfa, 0xac, 0xd5, 0x7a, 0x90, 0x43, 0x4f, 0x64,
+      0xd0, 0x36, 0x2f, 0x2a, 0x2d, 0x2d, 0x0a, 0x90, 0xcf, 0x1a, 0x5a, 0x4c,
+      0x5d, 0xb0, 0x2d, 0x56, 0xec, 0xc4, 0xc5, 0xbf, 0x34, 0x00, 0x72, 0x08,
+      0xd5, 0xb8, 0x87, 0x18, 0x58, 0x65
+    }
+  },
+  {
+    EVP_sha256,
+    {
+      0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b,
+      0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
+      0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20, 0x21, 0x22, 0x23,
+      0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
+      0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b,
+      0x3c, 0x3d, 0x3e, 0x3f, 0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47,
+      0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f
+    }, 80,
+    {
+      0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b,
+      0x6c, 0x6d, 0x6e, 0x6f, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,
+      0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, 0x80, 0x81, 0x82, 0x83,
+      0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
+      0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0x9b,
+      0x9c, 0x9d, 0x9e, 0x9f, 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
+      0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf
+    }, 80,
+    {
+      0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xbb,
+      0xbc, 0xbd, 0xbe, 0xbf, 0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
+      0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf, 0xd0, 0xd1, 0xd2, 0xd3,
+      0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf,
+      0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea, 0xeb,
+      0xec, 0xed, 0xee, 0xef, 0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
+      0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff
+    }, 80,
+    82, {
+      0xb1, 0x1e, 0x39, 0x8d, 0xc8, 0x03, 0x27, 0xa1, 0xc8, 0xe7, 0xf7, 0x8c,
+      0x59, 0x6a, 0x49, 0x34, 0x4f, 0x01, 0x2e, 0xda, 0x2d, 0x4e, 0xfa, 0xd8,
+      0xa0, 0x50, 0xcc, 0x4c, 0x19, 0xaf, 0xa9, 0x7c, 0x59, 0x04, 0x5a, 0x99,
+      0xca, 0xc7, 0x82, 0x72, 0x71, 0xcb, 0x41, 0xc6, 0x5e, 0x59, 0x0e, 0x09,
+      0xda, 0x32, 0x75, 0x60, 0x0c, 0x2f, 0x09, 0xb8, 0x36, 0x77, 0x93, 0xa9,
+      0xac, 0xa3, 0xdb, 0x71, 0xcc, 0x30, 0xc5, 0x81, 0x79, 0xec, 0x3e, 0x87,
+      0xc1, 0x4c, 0x01, 0xd5, 0xc1, 0xf3, 0x43, 0x4f, 0x1d, 0x87
+    }
+  },
+  {
+    EVP_sha256,
+    {
+      0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
+      0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
+    }, 22,
+    {
+    }, 0,
+    {
+    }, 0,
+    42, {
+      0x8d, 0xa4, 0xe7, 0x75, 0xa5, 0x63, 0xc1, 0x8f, 0x71, 0x5f, 0x80, 0x2a,
+      0x06, 0x3c, 0x5a, 0x31, 0xb8, 0xa1, 0x1f, 0x5c, 0x5e, 0xe1, 0x87, 0x9e,
+      0xc3, 0x45, 0x4e, 0x5f, 0x3c, 0x73, 0x8d, 0x2d, 0x9d, 0x20, 0x13, 0x95,
+      0xfa, 0xa4, 0xb6, 0x1a, 0x96, 0xc8
+    }
+  },
+  {
+    EVP_sha1,
+    {
+      0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
+    }, 11,
+    {
+      0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b,
+      0x0c,
+    }, 13,
+    {
+      0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8, 0xf9,
+    }, 10,
+    42, {
+      0x08, 0x5a, 0x01, 0xea, 0x1b, 0x10, 0xf3, 0x69, 0x33, 0x06, 0x8b, 0x56,
+      0xef, 0xa5, 0xad, 0x81, 0xa4, 0xf1, 0x4b, 0x82, 0x2f, 0x5b, 0x09, 0x15,
+      0x68, 0xa9, 0xcd, 0xd4, 0xf1, 0x55, 0xfd, 0xa2, 0xc2, 0x2e, 0x42, 0x24,
+      0x78, 0xd3, 0x05, 0xf3, 0xf8, 0x96
+    }
+  },
+  {
+    EVP_sha1,
+    {
+      0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b,
+      0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
+      0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20, 0x21, 0x22, 0x23,
+      0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
+      0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b,
+      0x3c, 0x3d, 0x3e, 0x3f, 0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47,
+      0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f
+    }, 80,
+    {
+      0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b,
+      0x6c, 0x6d, 0x6e, 0x6f, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,
+      0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, 0x80, 0x81, 0x82, 0x83,
+      0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
+      0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0x9b,
+      0x9c, 0x9d, 0x9e, 0x9f, 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
+      0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf
+    }, 80,
+    {
+      0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xbb,
+      0xbc, 0xbd, 0xbe, 0xbf, 0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
+      0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf, 0xd0, 0xd1, 0xd2, 0xd3,
+      0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf,
+      0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea, 0xeb,
+      0xec, 0xed, 0xee, 0xef, 0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
+      0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff
+    }, 80,
+    82, {
+      0x0b, 0xd7, 0x70, 0xa7, 0x4d, 0x11, 0x60, 0xf7, 0xc9, 0xf1, 0x2c, 0xd5,
+      0x91, 0x2a, 0x06, 0xeb, 0xff, 0x6a, 0xdc, 0xae, 0x89, 0x9d, 0x92, 0x19,
+      0x1f, 0xe4, 0x30, 0x56, 0x73, 0xba, 0x2f, 0xfe, 0x8f, 0xa3, 0xf1, 0xa4,
+      0xe5, 0xad, 0x79, 0xf3, 0xf3, 0x34, 0xb3, 0xb2, 0x02, 0xb2, 0x17, 0x3c,
+      0x48, 0x6e, 0xa3, 0x7c, 0xe3, 0xd3, 0x97, 0xed, 0x03, 0x4c, 0x7f, 0x9d,
+      0xfe, 0xb1, 0x5c, 0x5e, 0x92, 0x73, 0x36, 0xd0, 0x44, 0x1f, 0x4c, 0x43,
+      0x00, 0xe2, 0xcf, 0xf0, 0xd0, 0x90, 0x0b, 0x52, 0xd3, 0xb4
+    }
+  },
+  {
+    EVP_sha1,
+    {
+      0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
+      0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
+    }, 22,
+    {
+    }, 0,
+    {
+    }, 0,
+    42, {
+      0x0a, 0xc1, 0xaf, 0x70, 0x02, 0xb3, 0xd7, 0x61, 0xd1, 0xe5, 0x52, 0x98,
+      0xda, 0x9d, 0x05, 0x06, 0xb9, 0xae, 0x52, 0x05, 0x72, 0x20, 0xa3, 0x06,
+      0xe0, 0x7b, 0x6b, 0x87, 0xe8, 0xdf, 0x21, 0xd0, 0xea, 0x00, 0x03, 0x3d,
+      0xe0, 0x39, 0x84, 0xd3, 0x49, 0x18
+    }
+  },
+  {
+    EVP_sha1,
+    {
+      0x0c, 0x0c, 0x0c, 0x0c, 0x0c, 0x0c, 0x0c, 0x0c, 0x0c, 0x0c, 0x0c, 0x0c,
+      0x0c, 0x0c, 0x0c, 0x0c, 0x0c, 0x0c, 0x0c, 0x0c, 0x0c, 0x0c,
+    }, 22,
+    {
+    }, 0,
+    {
+    }, 0,
+    42, {
+      0x2c, 0x91, 0x11, 0x72, 0x04, 0xd7, 0x45, 0xf3, 0x50, 0x0d, 0x63, 0x6a,
+      0x62, 0xf6, 0x4f, 0x0a, 0xb3, 0xba, 0xe5, 0x48, 0xaa, 0x53, 0xd4, 0x23,
+      0xb0, 0xd1, 0xf2, 0x7e, 0xbb, 0xa6, 0xf5, 0xe5, 0x67, 0x3a, 0x08, 0x1d,
+      0x70, 0xcc, 0xe7, 0xac, 0xfc, 0x48
+    }
+  },
+};
+
+int main(void) {
+  uint8_t buf[82];
+  size_t i;
+
+  CRYPTO_library_init();
+  ERR_load_crypto_strings();
+
+  for (i = 0; i < sizeof(kTests) / sizeof(kTests[0]); i++) {
+    const hkdf_test_vector_t *test = &kTests[i];
+    if (!HKDF(buf, test->out_len, test->md_func(), test->ikm, test->ikm_len,
+              test->salt, test->salt_len, test->info, test->info_len)) {
+      fprintf(stderr, "Call to HKDF failed\n");
+      BIO_print_errors_fp(stderr);
+      return 1;
+    }
+    if (memcmp(buf, test->out, test->out_len) != 0) {
+      fprintf(stderr, "%u: Resulting key material does not match test vector\n",
+              (unsigned)i);
+      return 1;
+    }
+  }
+
+  printf("PASS\n");
+  ERR_free_strings();
+  return 0;
+}
diff --git a/include/openssl/err.h b/include/openssl/err.h
index b9c48c3..ca1f6c4 100644
--- a/include/openssl/err.h
+++ b/include/openssl/err.h
@@ -403,6 +403,7 @@
   ERR_LIB_DIGEST,
   ERR_LIB_CIPHER,
   ERR_LIB_USER,
+  ERR_LIB_HKDF,
   ERR_NUM_LIBS
 };
 
@@ -442,6 +443,7 @@
 #define ERR_R_USER_LIB ERR_LIB_USER
 #define ERR_R_DIGEST_LIB ERR_LIB_DIGEST
 #define ERR_R_CIPHER_LIB ERR_LIB_CIPHER
+#define ERR_R_HKDF_LIB ERR_LIB_HKDF
 
 /* Global reasons. */
 #define ERR_R_FATAL 64
diff --git a/include/openssl/hkdf.h b/include/openssl/hkdf.h
new file mode 100644
index 0000000..4091b84
--- /dev/null
+++ b/include/openssl/hkdf.h
@@ -0,0 +1,45 @@
+/* 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. */
+
+#ifndef OPENSSL_HEADER_HKDF_H
+#define OPENSSL_HEADER_HKDF_H
+
+#include <openssl/base.h>
+
+#ifdef  __cplusplus
+extern "C" {
+#endif
+
+
+/* Computes HKDF (as specified by RFC 5869) of initial keying material |secret|
+ * with |salt| and |info| using |digest|, and outputs |out_len| bytes to
+ * |out_key|. It returns one on success and zero on error.
+ *
+ * HKDF is an Extract-and-Expand algorithm. It does not do any key stretching,
+ * and as such, is not suited to be used alone to generate a key from a
+ * password. */
+OPENSSL_EXPORT 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);
+
+
+#if defined(__cplusplus)
+}  /* extern C */
+#endif
+
+#define HKDF_F_HKDF 100
+#define HKDF_R_OUTPUT_TOO_LARGE 100
+
+#endif  /* OPENSSL_HEADER_HKDF_H */
diff --git a/util/all_tests.sh b/util/all_tests.sh
index 55588f0..f38bba8 100644
--- a/util/all_tests.sh
+++ b/util/all_tests.sh
@@ -40,6 +40,7 @@
 ./crypto/ecdsa/ecdsa_test
 ./crypto/err/err_test
 ./crypto/evp/evp_test
+./crypto/hkdf/hkdf_test
 ./crypto/hmac/hmac_test
 ./crypto/lhash/lhash_test
 ./crypto/modes/gcm_test