103 lines
6.3 KiB
C
103 lines
6.3 KiB
C
/*********************************************************************************
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* MIT License
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*
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* Copyright (c) 2020-2024 Gregg E. Berman
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*
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* https://github.com/HomeSpan/HomeSpan
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*
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********************************************************************************/
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#pragma once
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#include <mbedtls/sha512.h>
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#include <mbedtls/bignum.h>
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#include <mbedtls/base64.h>
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#include "Utils.h"
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/////////////////////////////////////////////////
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// Pair-Setup Code Verification Data and Salt
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struct Verification {
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uint8_t salt[16];
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uint8_t verifyCode[384];
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};
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/////////////////////////////////////////////////
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// SRP-6A Structure from RFC 5054 (Nov 2007)
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// ** HAP uses N=3072-bit Group specified in RFC 5054 with Generator g=5
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// ** HAP replaces H=SHA-1 with H=SHA-512 (HAP Section 5.5)
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//
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// I = SRP-6A username, defined by HAP to be the word "Pair-Setup"
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// P = SRP-6A password, defined to be equal to the accessory's 8-digit setup code in the format "XXX-XX-XXX"
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struct SRP6A {
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static constexpr char N3072[]="FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74"
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"020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F1437"
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"4FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7ED"
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"EE386BFB5A899FA5AE9F24117C4B1FE649286651ECE45B3DC2007CB8A163BF05"
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"98DA48361C55D39A69163FA8FD24CF5F83655D23DCA3AD961C62F356208552BB"
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"9ED529077096966D670C354E4ABC9804F1746C08CA18217C32905E462E36CE3B"
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"E39E772C180E86039B2783A2EC07A28FB5C55DF06F4C52C9DE2BCBF695581718"
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"3995497CEA956AE515D2261898FA051015728E5A8AAAC42DAD33170D04507A33"
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"A85521ABDF1CBA64ECFB850458DBEF0A8AEA71575D060C7DB3970F85A6E1E4C7"
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"ABF5AE8CDB0933D71E8C94E04A25619DCEE3D2261AD2EE6BF12FFA06D98A0864"
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"D87602733EC86A64521F2B18177B200CBBE117577A615D6C770988C0BAD946E2"
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"08E24FA074E5AB3143DB5BFCE0FD108E4B82D120A93AD2CAFFFFFFFFFFFFFFFF";
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static const uint8_t g3072=5;
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static constexpr char I[]="Pair-Setup";
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mbedtls_mpi N; // N - 3072-bit Group pre-defined prime used for all SRP-6A calculations (384 bytes)
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mbedtls_mpi g; // g - pre-defined generator for the specified 3072-bit Group (g=5)
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mbedtls_mpi k; // k = H(N | PAD(g)) - SRP-6A multiplier (which is different from versions SRP-6 or SRP-3)
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mbedtls_mpi s; // s - randomly-generated salt (16 bytes)
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mbedtls_mpi x; // x = H(s | H(I | ":" | P)) - salted, double-hash of username and password (64 bytes)
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mbedtls_mpi v; // v = g^x %N - SRP-6A verifier (max 384 bytes)
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mbedtls_mpi b; // b - randomly-generated private key for this HAP accessory (i.e. the SRP Server) (32 bytes)
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mbedtls_mpi B; // B = k*v + g^b %N - public key for this accessory (max 384 bytes)
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mbedtls_mpi A; // A - public key RECEIVED from HAP Client (max 384 bytes)
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mbedtls_mpi u; // u = H(PAD(A) | PAB(B)) - "u-factor" (64 bytes)
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mbedtls_mpi S; // S = (A*v^u)^b %N - SRP shared "premaster" key, based on accessory private key and client public key (max 384 bytes)
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uint8_t K[64]; // K = H(S) - SRP SHARED SECRET KEY (64 bytes)
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uint8_t M1[64]; // M1 - proof RECEIVED from HAP Client (64 bytes)
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mbedtls_mpi t1; // temp1 - temporary mpi structures for intermediate results
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mbedtls_mpi t2; // temp2 - temporary mpi structures for intermediate results
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mbedtls_mpi t3; // temp3 - temporary mpi structures for intermediate results
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mbedtls_mpi _rr; // _rr - temporary "helper" for large exponential modulus calculations
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SRP6A(); // initializes N, G, and computes k
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~SRP6A();
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void *operator new(size_t size){return(HS_MALLOC(size));} // override new operator to use PSRAM when available
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void createVerifyCode(const char *setupCode, Verification *vData); // generates random s and computes v; writes back resulting Verification Data
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void createPublicKey(const Verification *vData, uint8_t *publicKey); // generates random b and computes k and B; writes back resulting Accessory Public Key
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void createSessionKey(const uint8_t *publicKey, size_t len); // computes u, S, and K from Client Public Key, A (of variable length)
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int verifyClientProof(const uint8_t *proof); // verifies Client Proof, M1, received from HAP client (return 1 on success, 0 on failure)
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void createAccProof(uint8_t *proof); // computes M2; write back resulting Accessory Proof
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void print(mbedtls_mpi *mpi); // prints size of mpi (in bytes), followed by the mpi itself (as a hex character string)
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};
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