diff options
Diffstat (limited to 'crypto/aes/aes_cfb.c')
-rw-r--r-- | crypto/aes/aes_cfb.c | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/crypto/aes/aes_cfb.c b/crypto/aes/aes_cfb.c index 9b569dda90..2e0c41ec2b 100644 --- a/crypto/aes/aes_cfb.c +++ b/crypto/aes/aes_cfb.c @@ -155,3 +155,96 @@ void AES_cfb128_encrypt(const unsigned char *in, unsigned char *out, *num=n; } +/* 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; + 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]; + /* 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) + 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); + } + /* it is not necessary to cleanse ovec, since the IV is not secret */ + } + +/* N.B. This expects the input to be packed, MS bit first */ +void AES_cfb1_encrypt(const unsigned char *in, unsigned char *out, + const unsigned long length, const AES_KEY *key, + unsigned char *ivec, int *num, const int enc) + { + unsigned int n; + unsigned char c[1],d[1]; + + assert(in && out && key && ivec && num); + assert(*num == 0); + + memset(out,0,(length+7)/8); + for(n=0 ; n < length ; ++n) + { + c[0]=(in[n/8]&(1 << (7-n%8))) ? 0x80 : 0; + AES_cfbr_encrypt_block(c,d,1,key,ivec,enc); + out[n/8]=(out[n/8]&~(1 << (7-n%8)))|((d[0]&0x80) >> (n%8)); + } + } + +void AES_cfb8_encrypt(const unsigned char *in, unsigned char *out, + const unsigned long length, const AES_KEY *key, + unsigned char *ivec, int *num, const int enc) + { + unsigned int n; + + assert(in && out && key && ivec && num); + assert(*num == 0); + + for(n=0 ; n < length ; ++n) + AES_cfbr_encrypt_block(&in[n],&out[n],8,key,ivec,enc); + } + |