/*
This file is part of Pretty Curved Privacy (pcp1).
Copyright (C) 2013-2014 T.v.Dein.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see .
You can contact me by mail: .
*/
#include "crypto.h"
size_t pcp_sodium_box(unsigned char **cipher,
unsigned char *cleartext,
size_t clearsize,
unsigned char *nonce,
unsigned char *secret,
unsigned char *pub) {
unsigned char *pad_clear;
unsigned char *pad_cipher;
size_t ciphersize = (clearsize + crypto_box_ZEROBYTES) - crypto_box_BOXZEROBYTES;
pad_cipher = ucmalloc(crypto_box_ZEROBYTES + clearsize);
pcp_pad_prepend(&pad_clear, cleartext, crypto_box_ZEROBYTES, clearsize);
/* crypto_box(c,m,mlen,n,pk,sk); */
crypto_box(pad_cipher, pad_clear,
clearsize + crypto_box_ZEROBYTES, nonce, pub, secret);
pcp_pad_remove(cipher, pad_cipher, crypto_secretbox_BOXZEROBYTES, ciphersize);
free(pad_clear);
free(pad_cipher);
return ciphersize;
}
int pcp_sodium_verify_box(unsigned char **cleartext, unsigned char* message,
size_t messagesize, unsigned char *nonce,
unsigned char *secret, unsigned char *pub) {
/* verify/decrypt the box */
unsigned char *pad_cipher;
unsigned char *pad_clear;
int success = -1;
pcp_pad_prepend(&pad_cipher, message, crypto_box_BOXZEROBYTES, messagesize);
pad_clear = (unsigned char *)ucmalloc((crypto_box_ZEROBYTES+ messagesize));
/* crypto_box_open(m,c,clen,n,pk,sk); */
if (crypto_box_open(pad_clear, pad_cipher,
messagesize + crypto_box_BOXZEROBYTES,
nonce, pub, secret) == 0) {
success = 0;
}
pcp_pad_remove(cleartext, pad_clear, crypto_box_ZEROBYTES, messagesize);
free(pad_clear);
free(pad_cipher);
return success;
}
unsigned char *pcp_box_encrypt(pcp_key_t *secret, pcp_pubkey_t *pub,
unsigned char *message, size_t messagesize,
size_t *csize) {
unsigned char *nonce = pcp_gennonce();
unsigned char *cipher;
size_t es = pcp_sodium_box(&cipher, message, messagesize, nonce,
secret->secret, pub->pub);
if(es <= messagesize) {
fatal("failed to encrypt message!\n");
goto errbec;
}
/* scip */
/* fprintf(stderr, "public: "); pcpprint_bin(stderr, pub->pub, 32); fprintf(stderr, "\n"); */
/* fprintf(stderr, "secret: "); pcpprint_bin(stderr, secret->secret, 32); fprintf(stderr, "\n"); */
/* fprintf(stderr, "cipher: "); pcpprint_bin(stderr, cipher, es); fprintf(stderr, "\n"); */
/* fprintf(stderr, " nonce: "); pcpprint_bin(stderr, nonce, crypto_secretbox_NONCEBYTES); fprintf(stderr, "\n"); */
/* put nonce and cipher together */
unsigned char *combined = ucmalloc(es + crypto_secretbox_NONCEBYTES);
memcpy(combined, nonce, crypto_secretbox_NONCEBYTES);
memcpy(&combined[crypto_secretbox_NONCEBYTES], cipher, es);
free(cipher);
free(nonce);
*csize = es + crypto_secretbox_NONCEBYTES;
return combined;
errbec:
if(cipher != NULL)
free(cipher);
free(nonce);
return NULL;
}
unsigned char *pcp_box_decrypt(pcp_key_t *secret, pcp_pubkey_t *pub,
unsigned char *cipher, size_t ciphersize,
size_t *dsize) {
unsigned char *message = NULL;
unsigned char *nonce = ucmalloc(crypto_secretbox_NONCEBYTES);
unsigned char *cipheronly = ucmalloc(ciphersize - crypto_secretbox_NONCEBYTES);
memcpy(nonce, cipher, crypto_secretbox_NONCEBYTES);
memcpy(cipheronly, &cipher[crypto_secretbox_NONCEBYTES],
ciphersize - crypto_secretbox_NONCEBYTES);
if(pcp_sodium_verify_box(&message, cipheronly,
ciphersize - crypto_secretbox_NONCEBYTES,
nonce, secret->secret, pub->pub) != 0){
fatal("failed to decrypt message!\n");
goto errbed;
}
free(nonce);
free(cipheronly);
/* resulting size: */
/* ciphersize - crypto_secretbox_ZEROBYTES */
*dsize = ciphersize - crypto_secretbox_NONCEBYTES - PCP_CRYPTO_ADD;
return message;
errbed:
free(nonce);
free(cipheronly);
if(message != NULL)
free(message);
return NULL;
}
size_t pcp_decrypt_stream(Pcpstream *in, Pcpstream* out, pcp_key_t *s, unsigned char *symkey, int verify) {
pcp_pubkey_t *cur = NULL;
pcp_pubkey_t *sender = NULL;
unsigned char *reccipher = NULL;
int nrec, recmatch;
uint32_t lenrec;
byte head[1];
size_t cur_bufsize, rec_size;
unsigned char rec_buf[PCP_ASYM_RECIPIENT_SIZE];
#ifdef PCP_ASYM_ADD_SENDER_PUB
unsigned char *senderpub;
#endif
int self = 0;
if(ps_tell(in) == 1) {
/* header has already been determined outside the lib */
if(symkey != NULL)
self = 1;
}
else {
/* step 1, check header */
cur_bufsize = ps_read(in, head, 1); /* fread(head, 1, 1, in); */
if(cur_bufsize != 1 && !ps_end(in) && !ps_err(in)) {
if(head[0] == PCP_SYM_CIPHER) {
if(symkey != NULL)
self = 1;
else {
fatal("Input is symetrically encrypted but no key have been specified (lib usage failure)\n");
goto errdef1;
}
}
else if(head[0] == PCP_ASYM_CIPHER) {
self = 0;
}
}
}
if(self) {
/* just decrypt symetrically and go outa here */
return pcp_decrypt_stream_sym(in, out, symkey, NULL);
}
#ifdef PCP_ASYM_ADD_SENDER_PUB
/* step 2, sender's pubkey */
cur_bufsize = ps_read(in, &in_buf, crypto_box_PUBLICKEYBYTES); /* fread(&in_buf, 1, crypto_box_PUBLICKEYBYTES, in); */
if(cur_bufsize != crypto_box_PUBLICKEYBYTES && !ps_end(in) && !ps_err(in)) {
fatal("Error: input file doesn't contain senders public key\n");
goto errdef1;
}
#endif
/* step 3, check len recipients */
cur_bufsize = ps_read(in, &lenrec, 4); /* fread(&lenrec, 1, 4, in); */
if(cur_bufsize != 4 && !ps_end(in) && !ps_err(in)) {
fatal("Error: input file doesn't contain recipient count\n");
goto errdef1;
}
lenrec = be32toh(lenrec);
if(verify) {
reccipher = ucmalloc(lenrec * PCP_ASYM_RECIPIENT_SIZE);
}
/* step 4, fetch recipient list and try to decrypt it for us */
for(nrec=0; nrecpub, crypto_box_PUBLICKEYBYTES);
/*fwrite(s->pub, crypto_box_PUBLICKEYBYTES, 1, out); */
/* fprintf(stderr, "D: sender pub - %d\n", crypto_box_PUBLICKEYBYTES); */
if(ps_err(out) != 0)
goto errec1;
#endif
/* step 3, len recipients, big endian */
lenrec = recipient_count;
lenrec = htobe32(lenrec);
ps_write(out, &lenrec, 4);
/* fwrite(&lenrec, 4, 1, out); */
/* fprintf(stderr, "D: %d recipients - 4\n", recipient_count); */
if(ps_err(out) != 0)
goto errec1;
/* step 4, recipient list */
ps_write(out, recipients_cipher, rec_size * recipient_count);
/* fwrite(recipients_cipher, rec_size * recipient_count, 1, out); */
/* fprintf(stderr, "D: recipients - %ld * %d\n", rec_size, recipient_count); */
if(ps_err(out) != 0)
goto errec1;
out_size = 5 + (rec_size * recipient_count) + crypto_box_PUBLICKEYBYTES;
/* step 5, actual encrypted data */
size_t sym_size = 0;
if(sign) {
pcp_rec_t *rec = pcp_rec_new(recipients_cipher, rec_size * recipient_count, s, NULL);
sym_size = pcp_encrypt_stream_sym(in, out, symkey, 1, rec);
pcp_rec_free(rec);
}
else
sym_size = pcp_encrypt_stream_sym(in, out, symkey, 1, NULL);
if(sym_size == 0)
goto errec1;
return out_size + sym_size;
errec1:
memset(symkey, 0, crypto_secretbox_KEYBYTES);
free(symkey);
free(recipients_cipher);
return 0;
}
size_t pcp_encrypt_stream_sym(Pcpstream *in, Pcpstream *out, unsigned char *symkey, int havehead, pcp_rec_t *recsign) {
/*
havehead = 0: write the whole thing from here
havehead = 1: no header, being called from asym...
*/
unsigned char *buf_nonce;
unsigned char *buf_cipher;
unsigned char in_buf[PCP_BLOCK_SIZE];
size_t cur_bufsize = 0;
size_t out_size = 0;
size_t es;
crypto_generichash_state *st = NULL;
unsigned char *hash = NULL;
byte head[1];
if(recsign != NULL) {
st = ucmalloc(sizeof(crypto_generichash_state));
hash = ucmalloc(crypto_generichash_BYTES_MAX);
crypto_generichash_init(st, NULL, 0, 0);
}
if(havehead == 0) {
head[0] = PCP_SYM_CIPHER;
es = ps_write(out, head, 1);
/* es = fwrite(head, 1, 1, out); */
if(ps_err(out) != 0) {
fatal("Failed to write encrypted output!\n");
return 0;
}
}
#ifdef PCP_CBC
/* write the IV, pad it with rubbish, since pcp_decrypt_file_sym */
/* reads in with PCP_BLOCK_SIZE_IN buffersize and uses the last */
/* PCP_BLOCK_SIZE as IV. */
unsigned char *iv = urmalloc(PCP_BLOCK_SIZE);
unsigned char *ivpad = urmalloc(PCP_BLOCK_SIZE_IN - PCP_BLOCK_SIZE);
ps_write(out, ivpad, PCP_BLOCK_SIZE_IN - PCP_BLOCK_SIZE);
ps_write(out, iv, PCP_BLOCK_SIZE);
/*
fwrite(ivpad, PCP_BLOCK_SIZE_IN - PCP_BLOCK_SIZE, 1, out);
fwrite(iv, PCP_BLOCK_SIZE, 1, out);*/
#endif
/* 32k-ECB-mode. FIXME: maybe support CBC as well or only use CBC? */
while(!ps_end(in)) {
cur_bufsize = ps_read(in, &in_buf, PCP_BLOCK_SIZE); /* fread(&in_buf, 1, PCP_BLOCK_SIZE, in); */
if(cur_bufsize <= 0)
break;
buf_nonce = pcp_gennonce();
#ifdef PCP_CBC
/* apply IV to current clear */
_xorbuf(iv, in_buf, cur_bufsize);
#endif
es = pcp_sodium_mac(&buf_cipher, in_buf, cur_bufsize, buf_nonce, symkey);
ps_write(out, buf_nonce, crypto_secretbox_NONCEBYTES);
ps_write(out, buf_cipher, es);
/*
fwrite(buf_nonce, crypto_secretbox_NONCEBYTES, 1, out);
fwrite(buf_cipher, es, 1, out); */
free(buf_nonce);
free(buf_cipher);
out_size += crypto_secretbox_NONCEBYTES + es;
if(recsign != NULL)
crypto_generichash_update(st, in_buf, cur_bufsize);
#ifdef PCP_CBC
/* make current cipher to next IV, ignore nonce and pad */
memcpy(iv, &buf_cipher[PCP_CRYPTO_ADD], PCP_BLOCK_SIZE);
#endif
}
if(ps_err(out) != 0) {
fatal("Failed to write encrypted output!\n");
goto errsym1;
}
if(recsign != NULL) {
/* add encrypted recipient list to the hash */
crypto_generichash_update(st, recsign->cipher, recsign->ciphersize);
crypto_generichash_final(st, hash, crypto_generichash_BYTES_MAX);
/* generate the actual signature */
unsigned char *signature = pcp_ed_sign(hash, crypto_generichash_BYTES_MAX, recsign->secret);
size_t siglen = crypto_sign_BYTES + crypto_generichash_BYTES_MAX;
/* encrypt it as well */
buf_nonce = pcp_gennonce();
es = pcp_sodium_mac(&buf_cipher, signature, siglen, buf_nonce, symkey);
ps_write(out, buf_nonce, crypto_secretbox_NONCEBYTES);
ps_write(out, buf_cipher, es);
/*
fwrite(buf_nonce, crypto_secretbox_NONCEBYTES, 1, out);
fwrite(buf_cipher, es, 1, out); */
free(st);
free(signature);
free(hash);
}
return out_size;
errsym1:
if(symkey != NULL) {
free(st);
free(hash);
}
return NULL;
}
size_t pcp_decrypt_stream_sym(Pcpstream *in, Pcpstream* out, unsigned char *symkey, pcp_rec_t *recverify) {
unsigned char *buf_nonce;
unsigned char *buf_cipher;
unsigned char *buf_clear;
size_t out_size, cur_bufsize, es;
size_t ciphersize = (PCP_BLOCK_SIZE_IN) - crypto_secretbox_NONCEBYTES;
unsigned char in_buf[PCP_BLOCK_SIZE_IN];
buf_nonce = ucmalloc(crypto_secretbox_NONCEBYTES);
buf_cipher = ucmalloc(ciphersize);
out_size = 0;
unsigned char *signature = NULL;
unsigned char *signature_cr = NULL;
size_t siglen = crypto_sign_BYTES + crypto_generichash_BYTES_MAX;
size_t siglen_cr = siglen + PCP_CRYPTO_ADD + crypto_secretbox_NONCEBYTES;
crypto_generichash_state *st = NULL;
unsigned char *hash = NULL;
if(recverify != NULL) {
st = ucmalloc(sizeof(crypto_generichash_state));
hash = ucmalloc(crypto_generichash_BYTES_MAX);
crypto_generichash_init(st, NULL, 0, 0);
signature_cr = ucmalloc(siglen_cr);
}
#ifdef PCP_CBC
unsigned char *iv = NULL; /* will be filled during 1st loop */
#endif
while(!ps_end(in)) {
cur_bufsize = ps_read(in, &in_buf, PCP_BLOCK_SIZE_IN); /* fread(&in_buf, 1, PCP_BLOCK_SIZE_IN, in); */
if(cur_bufsize <= PCP_CRYPTO_ADD)
break; /* no valid cipher block */
if(recverify != NULL) {
if(cur_bufsize < PCP_BLOCK_SIZE_IN || ps_end(in)) {
/* pull out signature */
memcpy(signature_cr, &in_buf[cur_bufsize - siglen_cr], siglen_cr);
cur_bufsize -= siglen_cr;
}
}
#ifdef PCP_CBC
if(iv == NULL) {
/* first block is the IV, don't write it out and skip to the next block */
iv = ucmalloc(PCP_BLOCK_SIZE);
memcpy(iv, &in_buf[PCP_CRYPTO_ADD + crypto_secretbox_NONCEBYTES], PCP_BLOCK_SIZE);
continue;
}
#endif
ciphersize = cur_bufsize - crypto_secretbox_NONCEBYTES;
memcpy(buf_nonce, in_buf, crypto_secretbox_NONCEBYTES);
memcpy(buf_cipher, &in_buf[crypto_secretbox_NONCEBYTES], ciphersize);
es = pcp_sodium_verify_mac(&buf_clear, buf_cipher, ciphersize, buf_nonce, symkey);
#ifdef PCP_CBC
/* take last IV and apply it to current clear */
_xorbuf(iv, buf_clear, cur_bufsize - (PCP_CRYPTO_ADD + crypto_secretbox_NONCEBYTES));
#endif
out_size += ciphersize - PCP_CRYPTO_ADD;
if(es == 0) {
ps_write(out, buf_clear, ciphersize - PCP_CRYPTO_ADD);
/* fwrite(buf_clear, ciphersize - PCP_CRYPTO_ADD, 1, out); */
if(recverify != NULL)
crypto_generichash_update(st, buf_clear, ciphersize - PCP_CRYPTO_ADD);
free(buf_clear);
if(ps_err(out) != 0) {
fatal("Failed to write decrypted output!\n");
out_size = 0;
break;
}
}
else {
fatal("Failed to decrypt file content!\n");
free(buf_clear);
out_size = 0;
break;
}
#ifdef PCP_CBC
/* use last cipher as next IV */
memcpy(iv, &in_buf[PCP_CRYPTO_ADD + crypto_secretbox_NONCEBYTES], PCP_BLOCK_SIZE);
#endif
}
free(buf_nonce);
free(buf_cipher);
if(recverify != NULL) {
/* decrypt the signature */
memcpy(buf_nonce, signature_cr, crypto_secretbox_NONCEBYTES);
es = pcp_sodium_verify_mac(&signature, &signature_cr[crypto_secretbox_NONCEBYTES],
siglen_cr - crypto_secretbox_NONCEBYTES, buf_nonce, symkey);
if(es == 0) {
/* add encrypted recipient list to the hash */
crypto_generichash_update(st, recverify->cipher, recverify->ciphersize);
crypto_generichash_final(st, hash, crypto_generichash_BYTES_MAX);
unsigned char *verifiedhash = NULL;
verifiedhash = pcp_ed_verify(signature, siglen, recverify->pub);
if(verifiedhash == NULL)
out_size = 0;
else {
if(memcmp(verifiedhash, hash, crypto_generichash_BYTES_MAX) != 0) {
/* sig verified, but the hash doesn't match */
fatal("signed hash doesn't match actual hash of signed decrypted file content\n");
out_size = 0;
}
free(verifiedhash);
}
}
else {
fatal("Failed to decrypt signature!\n");
out_size = 0;
}
free(st);
free(hash);
free(signature);
free(signature_cr);
}
return out_size;
}
pcp_rec_t *pcp_rec_new(unsigned char *cipher, size_t clen, pcp_key_t *secret, pcp_pubkey_t *pub) {
pcp_rec_t *r = ucmalloc(sizeof(pcp_rec_t));
r->cipher = ucmalloc(clen);
memcpy(r->cipher, cipher, clen);
r->ciphersize = clen;
if(secret != NULL) {
r->secret = ucmalloc(sizeof(pcp_key_t));
memcpy(r->secret, secret, sizeof(pcp_key_t));
}
else
r->secret = NULL;
if(pub != NULL) {
r->pub = ucmalloc(sizeof(pcp_key_t));
memcpy(r->pub, pub, sizeof(pcp_key_t));
}
else
r->pub = NULL;
return r;
}
void pcp_rec_free(pcp_rec_t *r) {
free(r->cipher);
if(r->secret != NULL) {
memset(r->secret, 0, sizeof(pcp_key_t));
free(r->secret);
}
if(r->pub != NULL) {
memset(r->pub, 0, sizeof(pcp_pubkey_t));
free(r->pub);
}
free(r);
}