Add support for key inversion using AES-NI
diff --git a/include/polarssl/aesni.h b/include/polarssl/aesni.h
index f3f9fc3..b66aa8a 100644
--- a/include/polarssl/aesni.h
+++ b/include/polarssl/aesni.h
@@ -81,6 +81,16 @@
const unsigned char a[16],
const unsigned char b[16] );
+/**
+ * \brief Compute decryption round keys from encryption round keys
+ *
+ * \param invkey Round keys for the equivalent inverse cipher
+ * \param fwdkey Original round keys (for encryption)
+ * \param nr Number of rounds (that is, number of round keys minus one)
+ */
+void aesni_inverse_key( unsigned char *invkey,
+ const unsigned char *fwdkey, int nr );
+
#endif /* POLARSSL_HAVE_X86_64 */
#endif /* POLARSSL_AESNI_H */
diff --git a/library/aes.c b/library/aes.c
index d2d1c0c..4477084 100644
--- a/library/aes.c
+++ b/library/aes.c
@@ -591,6 +591,15 @@
if( ret != 0 )
return( ret );
+#if defined(POLARSSL_AESNI_C) && defined(POLARSSL_HAVE_X86_64)
+ if( aesni_supports( POLARSSL_AESNI_AES ) )
+ {
+ aesni_inverse_key( (unsigned char *) ctx->rk,
+ (const unsigned char *) cty.rk, ctx->nr );
+ goto done;
+ }
+#endif
+
SK = cty.rk + cty.nr * 4;
*RK++ = *SK++;
@@ -614,6 +623,7 @@
*RK++ = *SK++;
*RK++ = *SK++;
+done:
memset( &cty, 0, sizeof( aes_context ) );
return( 0 );
diff --git a/library/aesni.c b/library/aesni.c
index 0431f78..488731c 100644
--- a/library/aesni.c
+++ b/library/aesni.c
@@ -215,6 +215,28 @@
return( 0 );
}
+/*
+ * Compute decryption round keys from encryption round keys
+ */
+void aesni_inverse_key( unsigned char *invkey,
+ const unsigned char *fwdkey, int nr )
+{
+ unsigned char *ik = invkey;
+ const unsigned char *fk = fwdkey + 16 * nr;
+
+ memcpy( ik, fk, 16 );
+
+ for( fk -= 16, ik += 16; fk > fwdkey; fk -= 16, ik += 16 )
+ asm( "movdqu (%0), %%xmm0 \n"
+ "aesimc %%xmm0, %%xmm0 \n"
+ "movdqu %%xmm0, (%1) \n"
+ :
+ : "r" (fk), "r" (ik)
+ : "memory", "xmm0" );
+
+ memcpy( ik, fk, 16 );
+}
+
#endif /* POLARSSL_HAVE_X86_64 */
#endif /* POLARSSL_AESNI_C */
