From 6faad239766accdcc007540f0b8b38d4709cd435 Mon Sep 17 00:00:00 2001
From: Sverker Eriksson <sverker@erlang.org>
Date: Wed, 4 Jul 2012 17:26:29 +0200
Subject: crypto: Allow aes_cfb_128_{en|de}crypt to accept unaligned data

Remove the need for padding up to 16-byte multiple.
---
 lib/crypto/c_src/crypto.c        |  3 +--
 lib/crypto/doc/src/crypto.xml    | 42 +++++++++++++++++++++++++++++++++-------
 lib/crypto/test/crypto_SUITE.erl | 17 ++++++++++++----
 3 files changed, 49 insertions(+), 13 deletions(-)

diff --git a/lib/crypto/c_src/crypto.c b/lib/crypto/c_src/crypto.c
index 4be593e208..a6a81d6fe2 100644
--- a/lib/crypto/c_src/crypto.c
+++ b/lib/crypto/c_src/crypto.c
@@ -954,8 +954,7 @@ static ERL_NIF_TERM aes_cfb_128_crypt(ErlNifEnv* env, int argc, const ERL_NIF_TE
 
     if (!enif_inspect_iolist_as_binary(env, argv[0], &key) || key.size != 16
 	|| !enif_inspect_binary(env, argv[1], &ivec) || ivec.size != 16
-	|| !enif_inspect_iolist_as_binary(env, argv[2], &text)
-	|| text.size % 16 != 0) {
+	|| !enif_inspect_iolist_as_binary(env, argv[2], &text)) {
 	return enif_make_badarg(env);
     }
 
diff --git a/lib/crypto/doc/src/crypto.xml b/lib/crypto/doc/src/crypto.xml
index 19db6c9dd4..2868fe05f0 100644
--- a/lib/crypto/doc/src/crypto.xml
+++ b/lib/crypto/doc/src/crypto.xml
@@ -643,16 +643,14 @@ Mpint() = <![CDATA[<<ByteLen:32/integer-big, Bytes:ByteLen/binary>>]]>
 
     <func>
       <name>aes_cfb_128_encrypt(Key, IVec, Text) -> Cipher</name>
-      <name>aes_cbc_128_encrypt(Key, IVec, Text) -> Cipher</name>
-      <fsummary>Encrypt <c>Text</c>according to AES in Cipher Feedback  mode or Cipher Block Chaining mode</fsummary>
+      <fsummary>Encrypt <c>Text</c>according to AES in Cipher Feedback mode</fsummary>
       <type>
         <v>Key = Text = iolist() | binary()</v>
         <v>IVec = Cipher = binary()</v>
       </type>
       <desc>
         <p>Encrypts <c>Text</c> according to AES in Cipher Feedback 
-          mode (CFB) or Cipher Block Chaining mode (CBC). <c>Text</c>
-          must be a multiple of 128 bits (16 bytes). <c>Key</c> is the
+          mode (CFB). <c>Key</c> is the
           AES key, and <c>IVec</c> is an arbitrary initializing vector.
           The lengths of <c>Key</c> and <c>IVec</c> must be 128 bits
           (16 bytes).</p>
@@ -660,15 +658,45 @@ Mpint() = <![CDATA[<<ByteLen:32/integer-big, Bytes:ByteLen/binary>>]]>
     </func>
     <func>
       <name>aes_cfb_128_decrypt(Key, IVec, Cipher) -> Text</name>
+      <fsummary>Decrypt <c>Cipher</c>according to AES in Cipher Feedback mode</fsummary>
+      <type>
+        <v>Key = Cipher = iolist() | binary()</v>
+        <v>IVec = Text = binary()</v>
+      </type>
+      <desc>
+        <p>Decrypts <c>Cipher</c> according to AES in Cipher Feedback Mode (CFB).
+          <c>Key</c> is the AES key, and <c>IVec</c> is an arbitrary
+          initializing vector. <c>Key</c> and <c>IVec</c> must have
+          the same values as those used when encrypting. The lengths of
+          <c>Key</c> and <c>IVec</c> must be 128 bits (16 bytes).</p>
+      </desc>
+    </func>
+    <func>
+      <name>aes_cbc_128_encrypt(Key, IVec, Text) -> Cipher</name>
+      <fsummary>Encrypt <c>Text</c>according to AES in Cipher Block Chaining mode</fsummary>
+      <type>
+        <v>Key = Text = iolist() | binary()</v>
+        <v>IVec = Cipher = binary()</v>
+      </type>
+      <desc>
+          <p>Encrypts <c>Text</c> according to AES in Cipher Block Chaining
+          mode (CBC). <c>Text</c>
+          must be a multiple of 128 bits (16 bytes). <c>Key</c> is the
+          AES key, and <c>IVec</c> is an arbitrary initializing vector.
+          The lengths of <c>Key</c> and <c>IVec</c> must be 128 bits
+          (16 bytes).</p>
+      </desc>
+    </func>
+    <func>
       <name>aes_cbc_128_decrypt(Key, IVec, Cipher) -> Text</name>
-      <fsummary>Decrypt <c>Cipher</c>according to AES in Cipher Feedback  mode or Cipher Block Chaining mode</fsummary>
+      <fsummary>Decrypt <c>Cipher</c>according to AES in Cipher Block Chaining mode</fsummary>
       <type>
         <v>Key = Cipher = iolist() | binary()</v>
         <v>IVec = Text = binary()</v>
       </type>
       <desc>
-        <p>Decrypts <c>Cipher</c> according to Cipher Feedback Mode (CFB)
-          or Cipher Block Chaining mode (CBC).
+          <p>Decrypts <c>Cipher</c> according to AES in Cipher Block
+          Chaining mode (CBC).
           <c>Key</c> is the AES key, and <c>IVec</c> is an arbitrary
           initializing vector. <c>Key</c> and <c>IVec</c> must have
           the same values as those used when encrypting. <c>Cipher</c>
diff --git a/lib/crypto/test/crypto_SUITE.erl b/lib/crypto/test/crypto_SUITE.erl
index 627c966dfb..196f00da5d 100644
--- a/lib/crypto/test/crypto_SUITE.erl
+++ b/lib/crypto/test/crypto_SUITE.erl
@@ -717,10 +717,19 @@ aes_cfb(Config) when is_list(Config) ->
     ?line Key =  hexstr2bin("2b7e151628aed2a6abf7158809cf4f3c"),
     ?line IVec = hexstr2bin("000102030405060708090a0b0c0d0e0f"),
     ?line Plain = hexstr2bin("6bc1bee22e409f96e93d7e117393172a"),
-    ?line Cipher = crypto:aes_cfb_128_encrypt(Key, IVec, Plain),
-    ?line m(Cipher, hexstr2bin("3b3fd92eb72dad20333449f8e83cfb4a")),
-    ?line m(Plain, 
-	    crypto:aes_cfb_128_decrypt(Key, IVec, Cipher)).
+    ?line Cipher = hexstr2bin("3b3fd92eb72dad20333449f8e83cfb4a"),
+
+    %% Try all prefixes of plain and cipher.
+    aes_cfb_do(byte_size(Plain), Plain, Cipher, Key, IVec).
+
+aes_cfb_do(N, Plain, Cipher, Key, IVec) when N >= 0 ->
+    <<P:N/binary, _/binary>> = Plain,
+    <<C:N/binary, _/binary>> = Cipher,
+    ?line C = crypto:aes_cfb_128_encrypt(Key, IVec, P),
+    ?line P = crypto:aes_cfb_128_decrypt(Key, IVec, C),
+    aes_cfb_do(N-1, Plain, Cipher, Key, IVec);
+aes_cfb_do(_, _, _, _, _) -> ok.
+
 
 %%
 %%
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