From ffef856e205bcaf42a1a9a8cc5fb4965fd459edc Mon Sep 17 00:00:00 2001
From: Daniel White <daniel@whitehouse.id.au>
Date: Thu, 27 Sep 2012 02:40:11 +1000
Subject: crypto: Provide a generic interface for HMAC generation

---
 lib/crypto/doc/src/crypto.xml | 17 +++++++++++++++++
 lib/crypto/src/crypto.erl     | 21 +++++++++++++++++++--
 2 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/lib/crypto/doc/src/crypto.xml b/lib/crypto/doc/src/crypto.xml
index 0f21441748..5e2a7acb97 100644
--- a/lib/crypto/doc/src/crypto.xml
+++ b/lib/crypto/doc/src/crypto.xml
@@ -342,6 +342,23 @@ Mpint() = <![CDATA[<<ByteLen:32/integer-big, Bytes:ByteLen/binary>>]]>
           is 96 bits (12 bytes).</p>
       </desc>
     </func>
+    <func>
+      <name>hmac(Type, Key, Data) -> Mac</name>
+      <name>hmac(Type, Key, Data, MacLength) -> Mac</name>
+      <fsummary></fsummary>
+      <type>
+	<v>Type = md5 | sha | sha224 | sha256 | sha384 | sha512</v>
+        <v>Key = iodata()</v>
+	<v>Data = iodata()</v>
+        <v>MacLength = integer()</v>
+	<v>Mac = binary()</v>
+      </type>
+      <desc>
+        <p>Computes a HMAC of type <c>Type</c> from <c>Data</c> using
+        <c>Key</c> as the authentication key.</p> <c>MacLength</c>
+        will limit the size of the resultant <c>Mac</c>.
+      </desc>
+    </func>
     <func>
       <name>hmac_init(Type, Key) -> Context</name>
       <fsummary></fsummary>
diff --git a/lib/crypto/src/crypto.erl b/lib/crypto/src/crypto.erl
index 461558a79e..5e7f1a948a 100644
--- a/lib/crypto/src/crypto.erl
+++ b/lib/crypto/src/crypto.erl
@@ -35,7 +35,7 @@
 -export([sha256_mac/2, sha256_mac/3]).
 -export([sha384_mac/2, sha384_mac/3]).
 -export([sha512_mac/2, sha512_mac/3]).
--export([hmac_init/2, hmac_update/2, hmac_final/1, hmac_final_n/2]).
+-export([hmac/3, hmac/4, hmac_init/2, hmac_update/2, hmac_final/1, hmac_final_n/2]).
 -export([des_cbc_encrypt/3, des_cbc_decrypt/3, des_cbc_ivec/1]).
 -export([des_ecb_encrypt/2, des_ecb_decrypt/2]).
 -export([des_cfb_encrypt/3, des_cfb_decrypt/3, des_cfb_ivec/2]).
@@ -107,7 +107,7 @@
 		    blowfish_ecb_encrypt, blowfish_ecb_decrypt, blowfish_ofb64_encrypt,
 		    des_cbc_ivec, des_cfb_ivec, erlint, mpint,
 		    hash, hash_init, hash_update, hash_final,
-		    hmac_init, hmac_update, hmac_final, hmac_final_n, info,
+		    hmac, hmac_init, hmac_update, hmac_final, hmac_final_n, info,
 		    rc2_cbc_encrypt, rc2_cbc_decrypt,
 		    info_lib]).
 
@@ -418,11 +418,28 @@ sha512_final_nif(_Context) -> ?nif_stub.
 %%
 %%  HMAC (multiple hash options)
 %%
+
+-spec hmac(_, iodata(), iodata()) -> binary().
+-spec hmac(_, iodata(), iodata(), integer()) -> binary().
 -spec hmac_init(atom(), iodata()) -> binary().                             
 -spec hmac_update(binary(), iodata()) -> binary().
 -spec hmac_final(binary()) -> binary().                             
 -spec hmac_final_n(binary(), integer()) -> binary().                             
 
+hmac(md5, Key, Data)    -> md5_mac(Key, Data);
+hmac(sha, Key, Data)    -> sha_mac(Key, Data);
+hmac(sha224, Key, Data) -> sha224_mac(Key, Data);
+hmac(sha256, Key, Data) -> sha256_mac(Key, Data);
+hmac(sha384, Key, Data) -> sha384_mac(Key, Data);
+hmac(sha512, Key, Data) -> sha512_mac(Key, Data).
+
+hmac(md5, Key, Data, Size)    -> md5_mac_n(Key, Data, Size);
+hmac(sha, Key, Data, Size)    -> sha_mac(Key, Data, Size);
+hmac(sha224, Key, Data, Size) -> sha224_mac(Key, Data, Size);
+hmac(sha256, Key, Data, Size) -> sha256_mac(Key, Data, Size);
+hmac(sha384, Key, Data, Size) -> sha384_mac(Key, Data, Size);
+hmac(sha512, Key, Data, Size) -> sha512_mac(Key, Data, Size).
+
 hmac_init(_Type, _Key) -> ?nif_stub.
 hmac_update(_Context, _Data) -> ? nif_stub.
 hmac_final(_Context) -> ? nif_stub.
-- 
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