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Add independent ciper and MAC algorithms negotiation for each direction #952

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192 changes: 138 additions & 54 deletions src/internal.c
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Original file line number Diff line number Diff line change
Expand Up @@ -570,13 +570,11 @@ static HandshakeInfo* HandshakeInfoNew(void* heap)
heap, DYNTYPE_HS);
if (newHs != NULL) {
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WMEMSET(newHs, 0, sizeof(HandshakeInfo));
newHs->expectMsgId = MSGID_NONE;
newHs->kexId = ID_NONE;
newHs->kexHashId = WC_HASH_TYPE_NONE;
newHs->pubKeyId = ID_NONE;
newHs->encryptId = ID_NONE;
newHs->macId = ID_NONE;
newHs->blockSz = MIN_BLOCK_SZ;
newHs->peerBlockSz = MIN_BLOCK_SZ;
/* peerEncryptId, peerMacId, peerAeadMode, peerMacSz: left at 0
* (== ID_NONE / no-MAC) by the WMEMSET above. */
newHs->eSz = (word32)sizeof(newHs->e);
newHs->xSz = (word32)sizeof(newHs->x);
#ifndef WOLFSSH_NO_DH_GEX_SHA256
Expand Down Expand Up @@ -2625,7 +2623,7 @@ static int GenerateKeys(WOLFSSH* ssh, byte hashId, byte doKeyPad)
Keys* sK = NULL;
int ret = WS_SUCCESS;

if (ssh == NULL)
if (ssh == NULL || ssh->handshake == NULL)
ret = WS_BAD_ARGUMENT;
else {
if (ssh->ctx->side == WOLFSSH_ENDPOINT_SERVER) {
Expand Down Expand Up @@ -2658,19 +2656,17 @@ static int GenerateKeys(WOLFSSH* ssh, byte hashId, byte doKeyPad)
sK->encKey, sK->encKeySz,
ssh->k, ssh->kSz, ssh->h, ssh->hSz,
ssh->sessionId, ssh->sessionIdSz, doKeyPad);
if (ret == WS_SUCCESS) {
if (!ssh->handshake->aeadMode) {
ret = GenerateKey(hashId, 'E',
cK->macKey, cK->macKeySz,
ssh->k, ssh->kSz, ssh->h, ssh->hSz,
ssh->sessionId, ssh->sessionIdSz, doKeyPad);
if (ret == WS_SUCCESS) {
ret = GenerateKey(hashId, 'F',
sK->macKey, sK->macKeySz,
ssh->k, ssh->kSz, ssh->h, ssh->hSz,
ssh->sessionId, ssh->sessionIdSz, doKeyPad);
}
}
if (ret == WS_SUCCESS && cK->macKeySz > 0) {
ret = GenerateKey(hashId, 'E',
cK->macKey, cK->macKeySz,
ssh->k, ssh->kSz, ssh->h, ssh->hSz,
ssh->sessionId, ssh->sessionIdSz, doKeyPad);
}
if (ret == WS_SUCCESS && sK->macKeySz > 0) {
ret = GenerateKey(hashId, 'F',
sK->macKey, sK->macKeySz,
ssh->k, ssh->kSz, ssh->h, ssh->hSz,
ssh->sessionId, ssh->sessionIdSz, doKeyPad);
}

#ifdef SHOW_SECRETS
Expand Down Expand Up @@ -4258,6 +4254,18 @@ static int DoKexInit(WOLFSSH* ssh, byte* buf, word32 len, word32* idx)
word32 cannedAlgoNamesSz;
word32 skipSz = 0;
word32 begin;
/* handshake->keys/encryptId/... always represent the LOCAL endpoint's
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@ejohnstown ejohnstown May 7, 2026

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I think this can get solved with adding just a few bytes and not having the pointers. We'd have byte c2sEncryptId, s2cEncryptId, s2cMacId, c2SMacId. Read those values. When we're done reading the message, we can check the side and do all the algorithm IDs or peer algorithm IDs depending on the side. All the other values that are based on the read-from-message IDs can be set as well. We'd also need s2cAeadMode and c2sAeadMode flags.

* outgoing direction; peer* counterparts represent the peer's outgoing
* (= our incoming) direction. Server: local=S2C, peer=C2S.
* Client: local=C2S, peer=S2C. These aliases let the four enc/MAC
* parse sections store results without inline side checks, and keep the
* fields consistent with what GenerateKeys/SendNewKeys/DoNewKeys expect. */
byte *c2sEncryptId = NULL, *c2sAeadMode = NULL, *c2sBlockSz = NULL,
*c2sMacId = NULL, *c2sMacSz = NULL;
Keys *c2sKeys = NULL;
byte *s2cEncryptId = NULL, *s2cAeadMode = NULL, *s2cBlockSz = NULL,
*s2cMacId = NULL, *s2cMacSz = NULL;
Keys *s2cKeys = NULL;

WLOG(WS_LOG_DEBUG, "Entering DoKexInit()");

Expand Down Expand Up @@ -4300,6 +4308,35 @@ static int DoKexInit(WOLFSSH* ssh, byte* buf, word32 len, word32* idx)
begin = *idx;
side = ssh->ctx->side;

if (side == WOLFSSH_ENDPOINT_SERVER) {
c2sEncryptId = &ssh->handshake->peerEncryptId;
c2sAeadMode = &ssh->handshake->peerAeadMode;
c2sBlockSz = &ssh->handshake->peerBlockSz;
c2sMacId = &ssh->handshake->peerMacId;
c2sMacSz = &ssh->handshake->peerMacSz;
c2sKeys = &ssh->handshake->peerKeys;
s2cEncryptId = &ssh->handshake->encryptId;
s2cAeadMode = &ssh->handshake->aeadMode;
s2cBlockSz = &ssh->handshake->blockSz;
s2cMacId = &ssh->handshake->macId;
s2cMacSz = &ssh->handshake->macSz;
s2cKeys = &ssh->handshake->keys;
}
else {
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c2sEncryptId = &ssh->handshake->encryptId;
c2sAeadMode = &ssh->handshake->aeadMode;
c2sBlockSz = &ssh->handshake->blockSz;
c2sMacId = &ssh->handshake->macId;
c2sMacSz = &ssh->handshake->macSz;
c2sKeys = &ssh->handshake->keys;
s2cEncryptId = &ssh->handshake->peerEncryptId;
s2cAeadMode = &ssh->handshake->peerAeadMode;
s2cBlockSz = &ssh->handshake->peerBlockSz;
s2cMacId = &ssh->handshake->peerMacId;
s2cMacSz = &ssh->handshake->peerMacSz;
s2cKeys = &ssh->handshake->peerKeys;
}

/* Check that the cookie exists inside the message */
if (begin + COOKIE_SZ > len) {
/* error, out of bounds */
Expand Down Expand Up @@ -4399,6 +4436,24 @@ static int DoKexInit(WOLFSSH* ssh, byte* buf, word32 len, word32* idx)
ret = WS_MATCH_ENC_ALGO_E;
}
}
if (ret == WS_SUCCESS) {
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*c2sEncryptId = algoId;
*c2sAeadMode = AeadModeForId(algoId);
*c2sBlockSz = BlockSzForId(algoId);
c2sKeys->encKeySz = KeySzForId(algoId);
if (!*c2sAeadMode) {
c2sKeys->ivSz = *c2sBlockSz;
}
else {
/* Reaching here requires an AEAD cipher ID, which requires
* WOLFSSH_NO_AES_GCM to be unset, hence WOLFSSH_NO_AEAD unset
* (see internal.h). */
c2sKeys->ivSz = AEAD_NONCE_SZ;
*c2sMacSz = *c2sBlockSz;
*c2sMacId = ID_NONE;
c2sKeys->macKeySz = 0;
}
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}
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/* Enc Algorithms - Server to Client */
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if (ret == WS_SUCCESS) {
Expand All @@ -4407,31 +4462,32 @@ static int DoKexInit(WOLFSSH* ssh, byte* buf, word32 len, word32* idx)
ret = GetNameList(list, &listSz, buf, len, &begin);
}
if (ret == WS_SUCCESS) {
algoId = MatchIdLists(side, list, listSz, &algoId, 1);
cannedAlgoNamesSz = AlgoListSz(ssh->algoListCipher);
cannedListSz = (word32)sizeof(cannedList);
ret = GetNameListRaw(cannedList, &cannedListSz,
(const byte*)ssh->algoListCipher, cannedAlgoNamesSz);
}
if (ret == WS_SUCCESS) {
algoId = MatchIdLists(side, list, listSz, cannedList, cannedListSz);
if (algoId == ID_UNKNOWN) {
WLOG(WS_LOG_DEBUG, "Unable to negotiate Encryption Algo S2C");
ret = WS_MATCH_ENC_ALGO_E;
}
}
if (ret == WS_SUCCESS) {
ssh->handshake->encryptId = algoId;
ssh->handshake->aeadMode = AeadModeForId(algoId);
ssh->handshake->blockSz = BlockSzForId(algoId);
ssh->handshake->keys.encKeySz =
ssh->handshake->peerKeys.encKeySz =
KeySzForId(algoId);
if (!ssh->handshake->aeadMode) {
ssh->handshake->keys.ivSz =
ssh->handshake->peerKeys.ivSz =
ssh->handshake->blockSz;
*s2cEncryptId = algoId;
*s2cAeadMode = AeadModeForId(algoId);
*s2cBlockSz = BlockSzForId(algoId);
s2cKeys->encKeySz = KeySzForId(algoId);
if (!*s2cAeadMode) {
s2cKeys->ivSz = *s2cBlockSz;
}
else {
#ifndef WOLFSSH_NO_AEAD
ssh->handshake->keys.ivSz =
ssh->handshake->peerKeys.ivSz =
AEAD_NONCE_SZ;
ssh->handshake->macSz = ssh->handshake->blockSz;
#endif
/* Same invariant as C2S: AEAD cipher ID implies !WOLFSSH_NO_AEAD. */
s2cKeys->ivSz = AEAD_NONCE_SZ;
*s2cMacSz = *s2cBlockSz;
*s2cMacId = ID_NONE;
s2cKeys->macKeySz = 0;
}
}

Expand All @@ -4441,7 +4497,7 @@ static int DoKexInit(WOLFSSH* ssh, byte* buf, word32 len, word32* idx)
listSz = (word32)sizeof(list);
ret = GetNameList(list, &listSz, buf, len, &begin);
}
if (ret == WS_SUCCESS && !ssh->handshake->aeadMode) {
if (ret == WS_SUCCESS && !*c2sAeadMode) {
cannedAlgoNamesSz = AlgoListSz(ssh->algoListMac);
cannedListSz = (word32)sizeof(cannedList);
ret = GetNameListRaw(cannedList, &cannedListSz,
Expand All @@ -4453,6 +4509,11 @@ static int DoKexInit(WOLFSSH* ssh, byte* buf, word32 len, word32* idx)
WLOG(WS_LOG_DEBUG, "Unable to negotiate MAC Algo C2S");
ret = WS_MATCH_MAC_ALGO_E;
}
else {
*c2sMacId = algoId;
*c2sMacSz = MacSzForId(algoId);
c2sKeys->macKeySz = KeySzForId(algoId);
}
}
}

Expand All @@ -4462,18 +4523,22 @@ static int DoKexInit(WOLFSSH* ssh, byte* buf, word32 len, word32* idx)
listSz = (word32)sizeof(list);
ret = GetNameList(list, &listSz, buf, len, &begin);
}
if (ret == WS_SUCCESS && !ssh->handshake->aeadMode) {
algoId = MatchIdLists(side, list, listSz, &algoId, 1);
if (algoId == ID_UNKNOWN) {
WLOG(WS_LOG_DEBUG, "Unable to negotiate MAC Algo S2C");
ret = WS_MATCH_MAC_ALGO_E;
}
else {
ssh->handshake->macId = algoId;
ssh->handshake->macSz = MacSzForId(algoId);
ssh->handshake->keys.macKeySz =
ssh->handshake->peerKeys.macKeySz =
KeySzForId(algoId);
if (ret == WS_SUCCESS && !*s2cAeadMode) {
cannedAlgoNamesSz = AlgoListSz(ssh->algoListMac);
cannedListSz = (word32)sizeof(cannedList);
ret = GetNameListRaw(cannedList, &cannedListSz,
(const byte*)ssh->algoListMac, cannedAlgoNamesSz);
if (ret == WS_SUCCESS) {
algoId = MatchIdLists(side, list, listSz, cannedList, cannedListSz);
if (algoId == ID_UNKNOWN) {
WLOG(WS_LOG_DEBUG, "Unable to negotiate MAC Algo S2C");
ret = WS_MATCH_MAC_ALGO_E;
}
else {
*s2cMacId = algoId;
*s2cMacSz = MacSzForId(algoId);
s2cKeys->macKeySz = KeySzForId(algoId);
}
}
}
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Expand Down Expand Up @@ -6226,11 +6291,11 @@ static int DoNewKeys(WOLFSSH* ssh, byte* buf, word32 len, word32* idx)
}

if (ret == WS_SUCCESS) {
ssh->peerEncryptId = ssh->handshake->encryptId;
ssh->peerMacId = ssh->handshake->macId;
ssh->peerBlockSz = ssh->handshake->blockSz;
ssh->peerMacSz = ssh->handshake->macSz;
ssh->peerAeadMode = ssh->handshake->aeadMode;
ssh->peerEncryptId = ssh->handshake->peerEncryptId;
ssh->peerMacId = ssh->handshake->peerMacId;
ssh->peerBlockSz = ssh->handshake->peerBlockSz;
ssh->peerMacSz = ssh->handshake->peerMacSz;
ssh->peerAeadMode = ssh->handshake->peerAeadMode;
WMEMCPY(&ssh->peerKeys, &ssh->handshake->peerKeys, sizeof(Keys));

switch (ssh->peerEncryptId) {
Expand Down Expand Up @@ -17960,6 +18025,25 @@ int wolfSSH_TestDoKexInit(WOLFSSH* ssh, byte* buf, word32 len, word32* idx)
return DoKexInit(ssh, buf, len, idx);
}

int wolfSSH_TestDoNewKeys(WOLFSSH* ssh)
{
/* DoNewKeys ignores buf/len/idx (marked WOLFSSH_UNUSED internally). */
return DoNewKeys(ssh, NULL, 0, NULL);
}

void wolfSSH_TestFreeHandshake(WOLFSSH* ssh)
{
if (ssh != NULL) {
HandshakeInfoFree(ssh->handshake, ssh->ctx ? ssh->ctx->heap : NULL);
ssh->handshake = NULL;
}
}

int wolfSSH_TestGenerateKeys(WOLFSSH* ssh, byte hashId)
{
return GenerateKeys(ssh, (enum wc_HashType)hashId, 1);
}

int wolfSSH_TestDoKexDhInit(WOLFSSH* ssh, byte* buf, word32 len, word32* idx)
{
return DoKexDhInit(ssh, buf, len, idx);
Expand Down
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