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Fixed incorrect implementation of key stuff: curve25519 and ed25519 keys are now generated separately, the pcp-proprietary "derived key" feature has been dropped.

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TLINDEN
2014-01-19 23:54:53 +01:00
parent 691786cc68
commit 79cd096be5
3 changed files with 27 additions and 84 deletions
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105
libpcp/key.c
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@@ -93,46 +93,32 @@ char *pcp_getkeyid(pcp_key_t *k) {
return id;
}
void pcp_keypairs(byte *csk, byte *cpk, byte *esk, byte *epk, byte *seed) {
void pcp_keypairs(byte *csk, byte *cpk, byte *esk, byte *epk) {
// generate ed25519 + curve25519 keypair from random seed
byte tmp[64];
byte *seed = urmalloc(32);
byte *tmp = urmalloc(32);
// ed25519 signing key
crypto_sign_seed_keypair(epk, esk, seed);
crypto_hash_sha512(tmp, seed, 32);
// curve25519 secret key
tmp[0] &= 248;
tmp[31] &= 63;
tmp[31] |= 64;
memcpy(csk, tmp, 32);
// curve25519 public key
crypto_scalarmult_curve25519_base(cpk, csk);
memset(tmp, 0, 64);
}
void pcp_ed_keypairs(byte *csk, byte *esk) {
// re-generate (derive) curve25519 secret from ed25519 secret
// (1st half = seed, 2nd half = pub)
byte tmp[64];
byte seed[32];
memcpy(seed, esk, 32);
crypto_hash_sha512(tmp, seed, 32);
tmp[0] &= 248;
tmp[31] &= 63;
tmp[31] |= 64;
memcpy(csk, tmp, 32);
memset(tmp, 0, 64);
memset(tmp, 0, 32);
}
pcp_key_t * pcpkey_new () {
byte pub[32] = { 0 };
byte pub[32] = { 0 };
byte secret[32] = { 0 };
byte edpub[32] = { 0 };
byte edsec[64] = { 0 };
byte edpub[32] = { 0 };
byte edsec[64] = { 0 };
byte *seed = urmalloc(32);
pcp_keypairs(secret, pub, edsec, edpub, seed);
pcp_keypairs(secret, pub, edsec, edpub);
// fill in our struct
pcp_key_t *key = urmalloc(sizeof(pcp_key_t));
@@ -167,14 +153,20 @@ pcp_key_t *pcpkey_encrypt(pcp_key_t *key, char *passphrase) {
unsigned char *encrypted;
size_t es;
es = pcp_sodium_mac(&encrypted, key->edsecret, 64, key->nonce, encryptkey);
unsigned char *both = ucmalloc(96);
memcpy(both, key->edsecret, 64);
memcpy(&both[64], key->secret, 32);
es = pcp_sodium_mac(&encrypted, both, 96, key->nonce, encryptkey);
memset(encryptkey, 0, 32);
memset(both, 0, 96);
free(encryptkey);
free(both);
if(es == 80) {
if(es == 112) {
// success
memcpy(key->encrypted, encrypted, 80);
memcpy(key->encrypted, encrypted, 112);
arc4random_buf(key->secret, 32);
arc4random_buf(key->edsecret, 64);
key->secret[0] = 0;
@@ -195,17 +187,15 @@ pcp_key_t *pcpkey_decrypt(pcp_key_t *key, char *passphrase) {
unsigned char *decrypted;
size_t es;
es = pcp_sodium_verify_mac(&decrypted, key->encrypted, 80, key->nonce, encryptkey);
es = pcp_sodium_verify_mac(&decrypted, key->encrypted, 112, key->nonce, encryptkey);
memset(encryptkey, 0, 32);
free(encryptkey);
if(es == 0) {
// success
byte secret[32] = { 0 };
pcp_ed_keypairs(secret, decrypted);
memcpy(key->secret, secret, 32);
memcpy(key->edsecret, decrypted, 64);
memcpy(key->secret, &decrypted[64], 32);
}
else {
fatal("failed to decrypt the secret key (got %d, expected 32)!\n", es);
@@ -306,53 +296,6 @@ pcp_pubkey_t *pubkey2native(pcp_pubkey_t *k) {
#endif
}
pcp_key_t *pcp_derive_pcpkey (pcp_key_t *ours, char *theirs) {
byte edpub[32] = { 0 };
byte edsec[64] = { 0 };
byte pub[32] = { 0 };
byte secret[32] = { 0 };
byte *seed = ucmalloc(32);
size_t thlen = strnlen(theirs, 255);
size_t inlen = 64 + thlen;
unsigned char *both = ucmalloc(inlen);
memcpy(both, ours->edsecret, 64);
memcpy(&both[64], theirs, thlen);
if(crypto_hash_sha256(seed, both, inlen) != 0) {
fatal("Failed to generate a hash of our pub key and recipient id!\n");
goto errdp1;
}
pcp_keypairs(secret, pub, edsec, edpub, seed);
pcp_key_t * tmp = pcpkey_new ();
memcpy(tmp->secret, secret, 32);
memcpy(tmp->edpub, edpub, 32);
memcpy(tmp->edsecret, edsec, 64);
memcpy(tmp->pub, pub, 32);
memcpy(tmp->owner, ours->owner, 255);
memcpy(tmp->mail, ours->mail, 255);
memcpy(tmp->id, pcp_getkeyid(tmp), 17);
memset(both, 0, inlen);
memset(seed, 0, 32);
free(both);
free(seed);
return tmp;
errdp1:
memset(both, 0, inlen);
free(both);
return NULL;
}
void pcp_seckeyblob(void *blob, pcp_key_t *k) {
memcpy(blob, k, PCP_RAW_KEYSIZE);