ref: 53fa826a8a695bcfade5c47f636f719c71e96b98
dir: /sys/src/libsec/port/ccpoly.c/
#include "os.h" #include <libsec.h> static void ccpolyotk(Chachastate *cs, DigestState *ds) { uchar otk[ChachaBsize]; memset(ds, 0, sizeof(*ds)); memset(otk, 0, 32); chacha_setblock(cs, 0); chacha_encrypt(otk, ChachaBsize, cs); poly1305(nil, 0, otk, 32, nil, ds); } static void ccpolypad(uchar *buf, ulong nbuf, DigestState *ds) { static uchar zeros[16] = {0}; ulong npad; if(nbuf == 0) return; poly1305(buf, nbuf, nil, 0, nil, ds); npad = nbuf % 16; if(npad == 0) return; poly1305(zeros, 16 - npad, nil, 0, nil, ds); } static void ccpolylen(ulong n, uchar tag[16], DigestState *ds) { uchar info[8]; info[0] = n; info[1] = n>>8; info[2] = n>>16; info[3] = n>>24; info[4] = 0; info[5] = 0; info[6] = 0; info[7] = 0; poly1305(info, 8, nil, 0, tag, ds); } void ccpoly_encrypt(uchar *dat, ulong ndat, uchar *aad, ulong naad, uchar tag[16], Chachastate *cs) { DigestState ds; ccpolyotk(cs, &ds); if(cs->ivwords == 2){ poly1305(aad, naad, nil, 0, nil, &ds); ccpolylen(naad, nil, &ds); chacha_encrypt(dat, ndat, cs); poly1305(dat, ndat, nil, 0, nil, &ds); ccpolylen(ndat, tag, &ds); } else { ccpolypad(aad, naad, &ds); chacha_encrypt(dat, ndat, cs); ccpolypad(dat, ndat, &ds); ccpolylen(naad, nil, &ds); ccpolylen(ndat, tag, &ds); } } int ccpoly_decrypt(uchar *dat, ulong ndat, uchar *aad, ulong naad, uchar tag[16], Chachastate *cs) { DigestState ds; uchar tmp[16]; ccpolyotk(cs, &ds); if(cs->ivwords == 2){ poly1305(aad, naad, nil, 0, nil, &ds); ccpolylen(naad, nil, &ds); poly1305(dat, ndat, nil, 0, nil, &ds); ccpolylen(ndat, tmp, &ds); } else { ccpolypad(aad, naad, &ds); ccpolypad(dat, ndat, &ds); ccpolylen(naad, nil, &ds); ccpolylen(ndat, tmp, &ds); } if(tsmemcmp(tag, tmp, 16) != 0) return -1; chacha_encrypt(dat, ndat, cs); return 0; }