Eliminate redundant memcpy of IV material. Performance improvement varies
authorAndy Polyakov <appro@openssl.org>
Sun, 26 Dec 2004 12:31:37 +0000 (12:31 +0000)
committerAndy Polyakov <appro@openssl.org>
Sun, 26 Dec 2004 12:31:37 +0000 (12:31 +0000)
from platform to platform and can be as large as 20%.

crypto/aes/aes_cbc.c

index 1222a21..e43135e 100644 (file)
@@ -65,7 +65,7 @@ void AES_cbc_encrypt(const unsigned char *in, unsigned char *out,
 
        unsigned long n;
        unsigned long len = length;
-       unsigned char tmp[AES_BLOCK_SIZE];
+       unsigned char tmp[AES_BLOCK_SIZE], *iv = ivec;
 
        assert(in && out && key && ivec);
        assert((AES_ENCRYPT == enc)||(AES_DECRYPT == enc));
@@ -73,22 +73,40 @@ void AES_cbc_encrypt(const unsigned char *in, unsigned char *out,
        if (AES_ENCRYPT == enc) {
                while (len >= AES_BLOCK_SIZE) {
                        for(n=0; n < AES_BLOCK_SIZE; ++n)
-                               tmp[n] = in[n] ^ ivec[n];
-                       AES_encrypt(tmp, out, key);
-                       memcpy(ivec, out, AES_BLOCK_SIZE);
+                               out[n] = in[n] ^ iv[n];
+                       AES_encrypt(out, out, key);
+                       iv = out;
                        len -= AES_BLOCK_SIZE;
                        in += AES_BLOCK_SIZE;
                        out += AES_BLOCK_SIZE;
                }
                if (len) {
                        for(n=0; n < len; ++n)
-                               tmp[n] = in[n] ^ ivec[n];
+                               tmp[n] = in[n] ^ iv[n];
                        for(n=len; n < AES_BLOCK_SIZE; ++n)
-                               tmp[n] = ivec[n];
+                               tmp[n] = iv[n];
                        AES_encrypt(tmp, tmp, key);
                        memcpy(out, tmp, AES_BLOCK_SIZE);
-                       memcpy(ivec, tmp, AES_BLOCK_SIZE);
+                       iv = out;
                }                       
+               memcpy(ivec,iv,AES_BLOCK_SIZE);
+       } else if (in != out) {
+               while (len >= AES_BLOCK_SIZE) {
+                       AES_decrypt(in, out, key);
+                       for(n=0; n < AES_BLOCK_SIZE; ++n)
+                               out[n] ^= iv[n];
+                       iv = in;
+                       len -= AES_BLOCK_SIZE;
+                       in  += AES_BLOCK_SIZE;
+                       out += AES_BLOCK_SIZE;
+               }
+               if (len) {
+                       AES_decrypt(in,tmp,key);
+                       for(n=0; n < len; ++n)
+                               out[n] = tmp[n] ^ iv[n];
+                       iv = in;
+               }
+               memcpy(ivec,iv,AES_BLOCK_SIZE);
        } else {
                while (len >= AES_BLOCK_SIZE) {
                        memcpy(tmp, in, AES_BLOCK_SIZE);