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Completed initial re-factoring of postPairSetup - must test!

This commit is contained in:
Gregg 2023-12-24 17:35:25 -06:00
parent edb0cc1be0
commit 0e0f1dcb1c
4 changed files with 54 additions and 63 deletions
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85
src/HAP.cpp
View File

@ -523,7 +523,7 @@ int HAPClient::postPairSetupURL(uint8_t *content, size_t len){
auto itSignature=subTLV.find(kTLVType_Signature);
auto itPublicKey=subTLV.find(kTLVType_PublicKey);
if(subTLV.len(itIdentifier)!=36 || subTLV.len(itSignature)!=crypto_sign_BYTES || subTLV.len(itPublicKey)<=0){
if(subTLV.len(itIdentifier)!=36 || subTLV.len(itSignature)!=crypto_sign_BYTES || subTLV.len(itPublicKey)!=crypto_sign_PUBLICKEYBYTES){
LOG0("\n*** ERROR: One or more of required 'Identifier,' 'PublicKey,' and 'Signature' TLV records for this step is bad or missing\n\n");
responseTLV.add(kTLVType_State,pairState_M6); // set State=<M6>
responseTLV.add(kTLVType_Error,tagError_Unknown); // set Error=Unknown (there is no specific error type for missing/bad TLV data)
@ -537,93 +537,70 @@ int HAPClient::postPairSetupURL(uint8_t *content, size_t len){
// Rather, it purposely does not transmit "iosDeviceX", which is derived from the SRP Shared Secret that only the Client and this Server know.
// Note that the SALT and INFO text fields now match those in HAP Section 5.6.6.1
uint8_t iosDeviceX[32];
hkdf.create(iosDeviceX,srp.sharedSecret,64,"Pair-Setup-Controller-Sign-Salt","Pair-Setup-Controller-Sign-Info"); // derive iosDeviceX from SRP Shared Secret using HKDF
const size_t iosDeviceXLen=32;
TempBuffer<uint8_t> iosDeviceX(32);
hkdf.create(iosDeviceX,srp.sharedSecret,64,"Pair-Setup-Controller-Sign-Salt","Pair-Setup-Controller-Sign-Info"); // derive iosDeviceX (32 bytes) from SRP Shared Secret using HKDF
uint8_t *iosDevicePairingID = tlv8.buf(kTLVType_Identifier); // set iosDevicePairingID from TLV record
size_t iosDevicePairingIDLen = tlv8.len(kTLVType_Identifier);
// Concatenate iosDeviceX, IOS ID, and IOS PublicKey into iosDeviceInfo
uint8_t *iosDeviceLTPK = tlv8.buf(kTLVType_PublicKey); // set iosDeviceLTPK (Ed25519 long-term public key) from TLV record
size_t iosDeviceLTPKLen = tlv8.len(kTLVType_PublicKey);
TempBuffer<uint8_t> iosDeviceInfo(iosDeviceX.len()+(*itIdentifier).len+(*itPublicKey).len);
Utils::memcat(iosDeviceInfo,3,iosDeviceX.get(),iosDeviceX.len(),(*itIdentifier).val.get(),(*itIdentifier).len,(*itPublicKey).val.get(),(*itPublicKey).len);
size_t iosDeviceInfoLen=iosDeviceXLen+iosDevicePairingIDLen+iosDeviceLTPKLen; // total size of re-constituted message, iosDeviceInfo
uint8_t iosDeviceInfo[iosDeviceInfoLen];
memcpy(iosDeviceInfo,iosDeviceX,iosDeviceXLen); // iosDeviceInfo = iosDeviceX
memcpy(iosDeviceInfo+iosDeviceXLen,iosDevicePairingID,iosDevicePairingIDLen); // +iosDevicePairingID
memcpy(iosDeviceInfo+iosDeviceXLen+iosDevicePairingIDLen,iosDeviceLTPK,iosDeviceLTPKLen); // +iosDeviceLTPK
uint8_t *iosDeviceSignature = tlv8.buf(kTLVType_Signature); // set iosDeviceSignature from TLV record (an Ed25519 should always be 64 bytes)
if(crypto_sign_verify_detached(iosDeviceSignature, iosDeviceInfo, iosDeviceInfoLen, iosDeviceLTPK) != 0){ // verify signature of iosDeviceInfo using iosDeviceLTPK
if(crypto_sign_verify_detached(*itSignature, iosDeviceInfo, iosDeviceInfo.len(), *itPublicKey) != 0){ // verify signature of iosDeviceInfo using iosDeviceLTPK
LOG0("\n*** ERROR: LPTK Signature Verification Failed\n\n");
tlv8.clear(); // clear TLV records
tlv8.val(kTLVType_State,pairState_M6); // set State=<M6>
tlv8.val(kTLVType_Error,tagError_Authentication); // set Error=Authentication
tlvRespond(); // send response to client
pairStatus=pairState_M1; // reset pairStatus to first step of unpaired
responseTLV.add(kTLVType_State,pairState_M6); // set State=<M6>
responseTLV.add(kTLVType_Error,tagError_Authentication); // set Error=Authentication
tlvRespond(responseTLV); // send response to client
pairStatus=pairState_M1; // reset pairStatus to first step of unpaired
return(0);
}
addController(iosDevicePairingID,iosDeviceLTPK,true); // save Pairing ID and LTPK for this Controller with admin privileges
addController(*itIdentifier,*itPublicKey,true); // save Pairing ID and LTPK for this Controller with admin privileges
// Now perform the above steps in reverse to securely transmit the AccessoryLTPK to the Controller (HAP Section 5.6.6.2)
uint8_t accessoryX[32];
TempBuffer<uint8_t> accessoryX(32);
hkdf.create(accessoryX,srp.sharedSecret,64,"Pair-Setup-Accessory-Sign-Salt","Pair-Setup-Accessory-Sign-Info"); // derive accessoryX from SRP Shared Secret using HKDF
const size_t accessoryXLen=32;
uint8_t *accessoryPairingID=accessory.ID; // set accessoryPairingID from storage
const size_t accessoryPairingIDLen=17;
// Concatenate accessoryX, Accessory ID, and Accessory PublicKey into accessoryInfo
uint8_t *accessoryLTPK=accessory.LTPK; // set accessoryLTPK (Ed25519 long-term public key) from storage
const size_t accessoryLTPKLen=32;
TempBuffer<uint8_t> accessoryInfo(accessoryX.len()+sizeof(accessory.ID)+sizeof(accessory.LTPK));
Utils::memcat(accessoryInfo,3,accessoryX.get(),accessoryX.len(),accessory.ID,sizeof(accessory.ID),accessory.LTPK,sizeof(accessory.LTPK));
const size_t accessoryInfoLen=accessoryXLen+accessoryPairingIDLen+accessoryLTPKLen; // total size of accessoryInfo
uint8_t accessoryInfo[accessoryInfoLen];
subTLV.clear(); // clear existing SUBTLV records
memcpy(accessoryInfo,accessoryX,accessoryXLen); // accessoryInfo = accessoryX
memcpy(accessoryInfo+accessoryXLen,accessoryPairingID,accessoryPairingIDLen); // +accessoryPairingID
memcpy(accessoryInfo+accessoryXLen+accessoryPairingIDLen,accessoryLTPK,accessoryLTPKLen); // +accessoryLTPK
itSignature=subTLV.add(kTLVType_Signature,64,NULL); // create blank Signature TLV with space for 64 bytes
tlv8.clear(); // clear existing TLV records
crypto_sign_detached(*itSignature,NULL,accessoryInfo,accessoryInfo.len(),accessory.LTSK); // produce signature of accessoryInfo using AccessoryLTSK (Ed25519 long-term secret key)
crypto_sign_detached(tlv8.buf(kTLVType_Signature,64),NULL,accessoryInfo,accessoryInfoLen,accessory.LTSK); // produce signature of accessoryInfo using AccessoryLTSK (Ed25519 long-term secret key)
tlv8.buf(kTLVType_Identifier,accessoryPairingID,accessoryPairingIDLen); // set Identifier TLV record as accessoryPairingID
tlv8.buf(kTLVType_PublicKey,accessoryLTPK,accessoryLTPKLen); // set PublicKey TLV record as accessoryLTPK
subTLV.add(kTLVType_Identifier,sizeof(accessory.ID),accessory.ID); // set Identifier TLV record as accessoryPairingID
subTLV.add(kTLVType_PublicKey,sizeof(accessory.LTPK),accessory.LTPK); // set PublicKey TLV record as accessoryLTPK
LOG2("------- ENCRYPTING SUB-TLVS -------\n");
tlv8.print(2);
subTLV.print();
size_t subTLVLen=tlv8.pack(NULL); // get size of buffer needed to store sub-TLV
uint8_t subTLV[subTLVLen];
subTLVLen=tlv8.pack(subTLV); // create sub-TLV by packing Identifier, PublicKey, and Signature TLV records together
TempBuffer<uint8_t> subPack(subTLV.pack_size()); // create sub-TLV by packing Identifier, PublicKey and Signature TLV records together
subTLV.pack(subPack);
tlv8.clear(); // clear existing TLV records
// Encrypt the subTLV data using the same sessionKey as above with ChaCha20-Poly1305
// Final step is to encrypt the subTLV data using the same sessionKey as above with ChaCha20-Poly1305
itEncryptedData=responseTLV.add(kTLVType_EncryptedData,subPack.len()+crypto_aead_chacha20poly1305_IETF_ABYTES,NULL); //create blank EncryptedData TLV with space for subTLV + Authentication Tag
unsigned long long edLen;
crypto_aead_chacha20poly1305_ietf_encrypt(tlv8.buf(kTLVType_EncryptedData),&edLen,subTLV,subTLVLen,NULL,0,NULL,(unsigned char *)"\x00\x00\x00\x00PS-Msg06",sessionKey);
crypto_aead_chacha20poly1305_ietf_encrypt(*itEncryptedData,NULL,subPack,subPack.len(),NULL,0,NULL,(unsigned char *)"\x00\x00\x00\x00PS-Msg06",sessionKey);
LOG2("---------- END SUB-TLVS! ----------\n");
tlv8.buf(kTLVType_EncryptedData,edLen); // set length of EncryptedData TLV record, which should now include the Authentication Tag at the end as required by HAP
tlv8.val(kTLVType_State,pairState_M6); // set State=<M6>
responseTLV.add(kTLVType_State,pairState_M6); // set State=<M6>
tlvRespond(); // send response to client
tlvRespond(responseTLV); // send response to client
mdns_service_txt_item_set("_hap","_tcp","sf","0"); // broadcast new status
mdns_service_txt_item_set("_hap","_tcp","sf","0"); // broadcast new status
LOG1("\n*** ACCESSORY PAIRED! ***\n");
STATUS_UPDATE(on(),HS_PAIRED)
if(homeSpan.pairCallback) // if set, invoke user-defined Pairing Callback to indicate device has been paired
if(homeSpan.pairCallback) // if set, invoke user-defined Pairing Callback to indicate device has been paired
homeSpan.pairCallback(true);
return(1);

14
src/HAP.h
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@ -65,10 +65,10 @@ struct Nonce {
// Paired Controller Structure for Permanently-Stored Data
struct Controller {
boolean allocated=false; // DEPRECATED (but needed for backwards compatability with original NVS storage of Controller info)
boolean admin; // Controller has admin privileges
uint8_t ID[36]; // Pairing ID
uint8_t LTPK[32]; // Long Term Ed2519 Public Key
boolean allocated=false; // DEPRECATED (but needed for backwards compatability with original NVS storage of Controller info)
boolean admin; // Controller has admin privileges
uint8_t ID[36]; // Pairing ID
uint8_t LTPK[crypto_sign_PUBLICKEYBYTES]; // Long Term Ed2519 Public Key
Controller(){}
@ -85,9 +85,9 @@ struct Controller {
// Accessory Structure for Permanently-Stored Data
struct Accessory {
uint8_t ID[17]; // Pairing ID in form "XX:XX:XX:XX:XX:XX"
uint8_t LTSK[64]; // secret key for Ed25519 signatures
uint8_t LTPK[32]; // public key for Ed25519 signatures
uint8_t ID[17]; // Pairing ID in form "XX:XX:XX:XX:XX:XX"
uint8_t LTSK[crypto_sign_SECRETKEYBYTES]; // secret key for Ed25519 signatures
uint8_t LTPK[crypto_sign_PUBLICKEYBYTES]; // public key for Ed25519 signatures
};
/////////////////////////////////////////////////

13
src/Utils.cpp
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@ -87,6 +87,19 @@ String Utils::mask(char *c, int n){
return(s);
} // mask
//////////////////////////////////////
void Utils::memcat(uint8_t *buf, size_t n...){
va_list args;
va_start(args, n);
while(n-->0){
uint8_t *addBuf=va_arg(args,uint8_t *);
size_t len=va_arg(args,size_t);
memcpy(buf,addBuf,len);
buf+=len;
}
}
////////////////////////////////
// PushButton //
////////////////////////////////

1
src/Utils.h
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@ -42,6 +42,7 @@ namespace Utils {
char *readSerial(char *c, int max); // read serial port into 'c' until <newline>, but storing only first 'max' characters (the rest are discarded)
String mask(char *c, int n); // simply utility that creates a String from 'c' with all except the first and last 'n' characters replaced by '*'
void memcat(uint8_t *buf, size_t n...);
}