From ef8bf4acd51c5eba9d205506b36e66da7a7bbc8b Mon Sep 17 00:00:00 2001
From: Kévin Le Gouguec <kevin.legouguec@airbus.com>
Date: Tue, 27 Nov 2018 10:16:54 +0100
Subject: Extraction de fonctions communes à ΘCB3 et SCT-2
MIME-Version: 1.0
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---
 src/ae-common.h     |  69 +++++++++++++++++++++++++++++++++
 src/lilliput-ae-i.c | 107 +++++++++++++---------------------------------------
 2 files changed, 95 insertions(+), 81 deletions(-)
 create mode 100644 src/ae-common.h

(limited to 'src')

diff --git a/src/ae-common.h b/src/ae-common.h
new file mode 100644
index 0000000..6343f98
--- /dev/null
+++ b/src/ae-common.h
@@ -0,0 +1,69 @@
+#ifndef AE_COMMON_H
+#define AE_COMMON_H
+
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+
+#include "cipher.h"
+#include "parameters.h"
+
+
+static inline uint8_t upper_nibble(uint8_t i)
+{
+    return i >> 4;
+}
+
+static inline uint8_t lower_nibble(uint8_t i)
+{
+    return i & 0x0f;
+}
+
+static inline void encrypt(const uint8_t K[KEY_BYTES],
+                           const uint8_t T[TWEAK_BYTES],
+                           const uint8_t M[BLOCK_BYTES],
+                           uint8_t C[BLOCK_BYTES])
+{
+    lilliput_tbc_encrypt(K, T, M, C);
+}
+
+static inline void decrypt(const uint8_t K[KEY_BYTES],
+                           const uint8_t T[TWEAK_BYTES],
+                           const uint8_t C[BLOCK_BYTES],
+                           uint8_t M[BLOCK_BYTES])
+{
+    lilliput_tbc_decrypt(K, T, C, M);
+}
+
+static inline void xor_into(uint8_t dest[BLOCK_BYTES], const uint8_t src[BLOCK_BYTES])
+{
+    for (size_t i=0; i<BLOCK_BYTES; i++)
+        dest[i] ^= src[i];
+}
+
+static inline void xor_arrays(size_t len, uint8_t out[len], const uint8_t a[len], const uint8_t b[len])
+{
+    for (size_t i=0; i<len; i++)
+        out[i] = a[i] ^ b[i];
+}
+
+static inline void pad10(size_t X_len, const uint8_t X[X_len], uint8_t padded[BLOCK_BYTES])
+{
+    /* pad10*(X) = X || 1 || 0^{n-|X|-1} */
+
+    /* Assume that len<BLOCK_BYTES. */
+
+    size_t pad_len = BLOCK_BYTES-X_len;
+
+    memcpy(padded+pad_len, X, X_len);
+
+    padded[pad_len-1] = 0x80;
+
+    if (pad_len > 1)
+    {
+        memset(padded, 0, pad_len-1);
+    }
+}
+
+
+#endif /* AE_COMMON_H */
diff --git a/src/lilliput-ae-i.c b/src/lilliput-ae-i.c
index 60a916b..5d1a630 100644
--- a/src/lilliput-ae-i.c
+++ b/src/lilliput-ae-i.c
@@ -2,6 +2,7 @@
 #include <stdint.h>
 #include <string.h>
 
+#include "ae-common.h"
 #include "cipher.h"
 #include "lilliput-ae.h"
 
@@ -12,62 +13,6 @@ static const uint8_t _0n[BLOCK_BYTES] = {
 };
 
 
-static uint8_t _upper_nibble(uint8_t i)
-{
-    return i >> 4;
-}
-
-static uint8_t _lower_nibble(uint8_t i)
-{
-    return i & 0x0f;
-}
-
-static void _encrypt(const uint8_t K[KEY_BYTES],
-                     const uint8_t T[TWEAK_BYTES],
-                     const uint8_t M[BLOCK_BYTES],
-                     uint8_t C[BLOCK_BYTES])
-{
-    lilliput_tbc_encrypt(K, T, M, C);
-}
-
-static void _decrypt(const uint8_t K[KEY_BYTES],
-                     const uint8_t T[TWEAK_BYTES],
-                     const uint8_t C[BLOCK_BYTES],
-                     uint8_t M[BLOCK_BYTES])
-{
-    lilliput_tbc_decrypt(K, T, C, M);
-}
-
-static void _xor_into(uint8_t dest[BLOCK_BYTES], const uint8_t src[BLOCK_BYTES])
-{
-    for (size_t i=0; i<BLOCK_BYTES; i++)
-        dest[i] ^= src[i];
-}
-
-static void _xor_arrays(size_t len, uint8_t out[len], const uint8_t a[len], const uint8_t b[len])
-{
-    for (size_t i=0; i<len; i++)
-        out[i] = a[i] ^ b[i];
-}
-
-static void _pad10(size_t X_len, const uint8_t X[X_len], uint8_t padded[BLOCK_BYTES])
-{
-    /* pad10*(X) = X || 1 || 0^{n-|X|-1} */
-
-    /* Assume that len<BLOCK_BYTES. */
-
-    size_t pad_len = BLOCK_BYTES-X_len;
-
-    memcpy(padded+pad_len, X, X_len);
-
-    padded[pad_len-1] = 0x80;
-
-    if (pad_len > 1)
-    {
-        memset(padded, 0, pad_len-1);
-    }
-}
-
 static void _fill_ad_tweak(
     uint8_t  prefix,
     uint64_t block_nb,
@@ -119,14 +64,14 @@ static void _fill_msg_tweak(
         tweak[i] = b;
     }
 
-    tweak[sizeof(block_nb)] = _lower_nibble(N[0]) << 4;
+    tweak[sizeof(block_nb)] = lower_nibble(N[0]) << 4;
 
     for (size_t i=1; i<NONCE_BYTES; i++)
     {
-        tweak[sizeof(block_nb)+i] = _lower_nibble(N[i]) << 4 ^ _upper_nibble(N[i-1]);
+        tweak[sizeof(block_nb)+i] = lower_nibble(N[i]) << 4 ^ upper_nibble(N[i-1]);
     }
 
-    tweak[TWEAK_BYTES-1] = prefix << 4 ^ _upper_nibble(N[NONCE_BYTES-1]);
+    tweak[TWEAK_BYTES-1] = prefix << 4 ^ upper_nibble(N[NONCE_BYTES-1]);
 }
 
 static void _process_associated_data(
@@ -148,17 +93,17 @@ static void _process_associated_data(
     for (size_t i=0; i<l_a; i++)
     {
         _fill_ad_tweak(0x2, i, tweak);
-        _encrypt(key, tweak, &A[i*BLOCK_BYTES], Ek_Ai);
-        _xor_into(Auth, Ek_Ai);
+        encrypt(key, tweak, &A[i*BLOCK_BYTES], Ek_Ai);
+        xor_into(Auth, Ek_Ai);
     }
 
     if (rest != 0)
     {
         uint8_t A_rest[BLOCK_BYTES];
-        _pad10(rest, &A[l_a*BLOCK_BYTES], A_rest);
+        pad10(rest, &A[l_a*BLOCK_BYTES], A_rest);
         _fill_ad_tweak(0x6, l_a, tweak);
-        _encrypt(key, tweak, A_rest, Ek_Ai);
-        _xor_into(Auth, Ek_Ai);
+        encrypt(key, tweak, A_rest, Ek_Ai);
+        xor_into(Auth, Ek_Ai);
     }
 }
 
@@ -182,30 +127,30 @@ static void _encrypt_message(
 
     for (size_t j=0; j<l; j++)
     {
-        _xor_into(checksum, &M[j*BLOCK_BYTES]);
+        xor_into(checksum, &M[j*BLOCK_BYTES]);
         _fill_msg_tweak(0x0, N, j, tweak);
-        _encrypt(key, tweak, &M[j*BLOCK_BYTES], &C[j*BLOCK_BYTES]);
+        encrypt(key, tweak, &M[j*BLOCK_BYTES], &C[j*BLOCK_BYTES]);
     }
 
     if (rest == 0)
     {
         _fill_msg_tweak(0x1, N, l-1, tweak);
-        _encrypt(key, tweak, checksum, Final);
+        encrypt(key, tweak, checksum, Final);
     }
     else
     {
         uint8_t M_rest[BLOCK_BYTES];
         uint8_t Pad[BLOCK_BYTES];
 
-        _pad10(rest, &M[l*BLOCK_BYTES], M_rest);
-        _xor_into(checksum, M_rest);
+        pad10(rest, &M[l*BLOCK_BYTES], M_rest);
+        xor_into(checksum, M_rest);
 
         _fill_msg_tweak(0x4, N, l, tweak);
-        _encrypt(key, tweak, _0n, Pad);
-        _xor_arrays(rest, &C[l*BLOCK_BYTES], &M[l*BLOCK_BYTES], Pad);
+        encrypt(key, tweak, _0n, Pad);
+        xor_arrays(rest, &C[l*BLOCK_BYTES], &M[l*BLOCK_BYTES], Pad);
 
         _fill_msg_tweak(0x5, N, l, tweak);
-        _encrypt(key, tweak, checksum, Final);
+        encrypt(key, tweak, checksum, Final);
     }
 }
 
@@ -230,14 +175,14 @@ static void _decrypt_message(
     for (size_t j=0; j<l; j++)
     {
         _fill_msg_tweak(0x0, N, j, tweak);
-        _decrypt(key, tweak, &C[j*BLOCK_BYTES], &M[j*BLOCK_BYTES]);
-        _xor_into(checksum, &M[j*BLOCK_BYTES]);
+        decrypt(key, tweak, &C[j*BLOCK_BYTES], &M[j*BLOCK_BYTES]);
+        xor_into(checksum, &M[j*BLOCK_BYTES]);
     }
 
     if (rest == 0)
     {
         _fill_msg_tweak(0x1, N, l-1, tweak);
-        _encrypt(key, tweak, checksum, Final);
+        encrypt(key, tweak, checksum, Final);
     }
     else
     {
@@ -245,14 +190,14 @@ static void _decrypt_message(
         uint8_t Pad[BLOCK_BYTES];
 
         _fill_msg_tweak(0x4, N, l, tweak);
-        _encrypt(key, tweak, _0n, Pad);
-        _xor_arrays(rest, &M[l*BLOCK_BYTES], &C[l*BLOCK_BYTES], Pad);
+        encrypt(key, tweak, _0n, Pad);
+        xor_arrays(rest, &M[l*BLOCK_BYTES], &C[l*BLOCK_BYTES], Pad);
 
-        _pad10(rest, &M[l*BLOCK_BYTES], M_rest);
-        _xor_into(checksum, M_rest);
+        pad10(rest, &M[l*BLOCK_BYTES], M_rest);
+        xor_into(checksum, M_rest);
 
         _fill_msg_tweak(0x5, N, l, tweak);
-        _encrypt(key, tweak, checksum, Final);
+        encrypt(key, tweak, checksum, Final);
     }
 }
 
@@ -262,7 +207,7 @@ static void _generate_tag(
     uint8_t       tag[TAG_BYTES]
 )
 {
-    _xor_arrays(TAG_BYTES, tag, Final, Auth);
+    xor_arrays(TAG_BYTES, tag, Final, Auth);
 }
 
 
-- 
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