From 2e4a99f38b86f068a444ef3f77d111a43c0267bb Mon Sep 17 00:00:00 2001 From: Andy Polyakov Date: Thu, 30 Dec 2004 10:43:33 +0000 Subject: [PATCH] AES-CFB[18] 2x optimization. Well, I bet nobody cares about AES-CFB1 performance, but anyway... --- crypto/aes/aes_cfb.c | 66 ++++++++++++++------------------------------ 1 file changed, 20 insertions(+), 46 deletions(-) diff --git a/crypto/aes/aes_cfb.c b/crypto/aes/aes_cfb.c index ab42cd5ecd..49f0411010 100644 --- a/crypto/aes/aes_cfb.c +++ b/crypto/aes/aes_cfb.c @@ -158,61 +158,35 @@ void AES_cfb128_encrypt(const unsigned char *in, unsigned char *out, /* This expects a single block of size nbits for both in and out. Note that it corrupts any extra bits in the last byte of out */ -/* Untested, once it is working, it will be optimised */ void AES_cfbr_encrypt_block(const unsigned char *in,unsigned char *out, const int nbits,const AES_KEY *key, unsigned char *ivec,const int enc) { - int n; + int n,rem,num; unsigned char ovec[AES_BLOCK_SIZE*2]; - assert(in && out && key && ivec); - if(enc) - { - /* construct the new IV */ - AES_encrypt(ivec,ovec,key); - /* encrypt the input */ - for(n=0 ; n < (nbits+7)/8 ; ++n) - out[n]=in[n]^ovec[n]; - /* fill in the first half of the new IV with the current IV */ - memcpy(ovec,ivec,AES_BLOCK_SIZE); - /* and put the ciphertext in the second half */ - memcpy(ovec+AES_BLOCK_SIZE,out,(nbits+7)/8); - /* shift ovec left most of the bits... */ - memmove(ovec,ovec+nbits/8,AES_BLOCK_SIZE+(nbits%8 ? 1 : 0)); - /* now the remaining bits */ - if(nbits%8 != 0) - for(n=0 ; n < AES_BLOCK_SIZE ; ++n) - { - ovec[n]<<=nbits%8; - ovec[n]|=ovec[n+1]>>(8-nbits%8); - } - /* finally, move it back into place */ - memcpy(ivec,ovec,AES_BLOCK_SIZE); - } - else - { - /* construct the new IV in the first half of ovec */ - AES_encrypt(ivec,ovec,key); - /* decrypt the input */ - for(n=0 ; n < (nbits+7)/8 ; ++n) - out[n]=in[n]^ovec[n]; + if (nbits<=0 || nbits>128) return; + /* fill in the first half of the new IV with the current IV */ memcpy(ovec,ivec,AES_BLOCK_SIZE); - /* append the ciphertext */ - memcpy(ovec+AES_BLOCK_SIZE,in,(nbits+7)/8); - /* shift ovec left most of the bits... */ - memmove(ovec,ovec+nbits/8,AES_BLOCK_SIZE+(nbits%8 ? 1 : 0)); - /* now the remaining bits */ - if(nbits%8 != 0) + /* construct the new IV */ + AES_encrypt(ivec,ivec,key); + num = (nbits+7)/8; + if (enc) /* encrypt the input */ + for(n=0 ; n < num ; ++n) + out[n] = (ovec[AES_BLOCK_SIZE+n] = in[n] ^ ivec[n]); + else /* decrypt the input */ + for(n=0 ; n < num ; ++n) + out[n] = (ovec[AES_BLOCK_SIZE+n] = in[n]) ^ ivec[n]; + /* shift ovec left... */ + rem = nbits%8; + num = nbits/8; + if(rem==0) + memcpy(ivec,ovec+num,AES_BLOCK_SIZE); + else for(n=0 ; n < AES_BLOCK_SIZE ; ++n) - { - ovec[n]<<=nbits%8; - ovec[n]|=ovec[n+1]>>(8-nbits%8); - } - /* finally, move it back into place */ - memcpy(ivec,ovec,AES_BLOCK_SIZE); - } + ivec[n] = ovec[n+num]<>(8-rem); + /* it is not necessary to cleanse ovec, since the IV is not secret */ } -- 2.25.1