ref: 4088f72903121c5b39cd5ce9445b2fdb2783c4c1
dir: /sys/src/libsec/port/aesOFB.c/
#include "os.h" #include <libsec.h> typedef ulong u32; void aesOFBencrypt(uchar *p, int len, AESstate *s) { u32 o = s->offset; while(len > 0){ if(o % 16){ Odd: *p++ ^= s->ivec[o++ % 16], len--; continue; } aes_encrypt(s->ekey, s->rounds, s->ivec, s->ivec); if(len < 16 || ((p-(uchar*)0) & 3) != 0) goto Odd; ((u32*)p)[0] ^= ((u32*)s->ivec)[0]; ((u32*)p)[1] ^= ((u32*)s->ivec)[1]; ((u32*)p)[2] ^= ((u32*)s->ivec)[2]; ((u32*)p)[3] ^= ((u32*)s->ivec)[3]; o += 16, p += 16, len -= 16; } s->offset = o; }