netxduo
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Outline
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#include "nx_crypto_hkdf.h"
#include "nx_crypto_hmac.h"
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_nx_crypto_method_hkdf_init(struct NX_CRYPTO_METHOD_STRUCT *, UCHAR *, NX_CRYPTO_KEY_SIZE, void **, void *, ULONG)
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_nx_crypto_method_hkdf_cleanup(void *)
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_nx_crypto_method_hkdf_operation(UINT, void *, struct NX_CRYPTO_METHOD_STRUCT *, UCHAR *, NX_CRYPTO_KEY_SIZE, UCHAR *, ULONG, UCHAR *, UCHAR *, ULONG, void *, ULONG, void *, void (*)(void *, UINT))
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_nx_crypto_hkdf_extract(NX_CRYPTO_HKDF *)
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_nx_crypto_hkdf_expand(NX_CRYPTO_HKDF *, UCHAR *, UINT)
Files
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CodeScopeSTM32 Libraries and Samplesnetxduocrypto_libraries/src/nx_crypto_hkdf.c
 
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/**************************************************************************/ /* */ /* Copyright (c) Microsoft Corporation. All rights reserved. */ /* */ /* This software is licensed under the Microsoft Software License */ /* Terms for Microsoft Azure RTOS. Full text of the license can be */ /* found in the LICENSE file at https://aka.ms/AzureRTOS_EULA */ /* and in the root directory of this software. */ /* */... /**************************************************************************/ ... /**************************************************************************/ /**************************************************************************/ /** */ /** NetX Crypto Component */ /** */ /** HMAC-based Extract-and-Expand Key Derivation Function (HKDF) */ /** */... /**************************************************************************/ /**************************************************************************/ #include "nx_crypto_hkdf.h" #include "nx_crypto_hmac.h" ... /**************************************************************************/ /* */ /* FUNCTION RELEASE */ /* */ /* _nx_crypto_method_hkdf_init PORTABLE C */ /* 6.1 */ /* AUTHOR */ /* */ /* Timothy Stapko, Microsoft Corporation */ /* */ /* DESCRIPTION */ /* */ /* This function is the common crypto method initialization routine */ /* for the Microsoft implementation of the HKDF cryptographic */ /* algorithm. */ /* */ /* INPUT */ /* */ /* method Pointer to crypto method */ /* key Pointer to key */ /* key_size_in_bits Length of key size in bits */ /* handler Returned crypto handler */ /* crypto_metadata Metadata area */ /* crypto_metadata_size Size of the metadata area */ /* */ /* OUTPUT */ /* */ /* status Completion status */ /* */ /* CALLS */ /* */ /* None */ /* */ /* CALLED BY */ /* */ /* Application Code */ /* */ /* RELEASE HISTORY */ /* */ /* DATE NAME DESCRIPTION */ /* */ /* 05-19-2020 Timothy Stapko Initial Version 6.0 */ /* 09-30-2020 Timothy Stapko Modified comment(s), */ /* resulting in version 6.1 */ /* */... /**************************************************************************/ NX_CRYPTO_KEEP UINT _nx_crypto_method_hkdf_init(struct NX_CRYPTO_METHOD_STRUCT *method, UCHAR *key, NX_CRYPTO_KEY_SIZE key_size_in_bits, VOID **handle, VOID *crypto_metadata, ULONG crypto_metadata_size) { NX_CRYPTO_HKDF *hkdf; NX_CRYPTO_PARAMETER_NOT_USED(handle); NX_CRYPTO_STATE_CHECK /* We don't need a key in the HKDF init. */ if ((method == NX_CRYPTO_NULL) || (crypto_metadata == NX_CRYPTO_NULL)) { return(NX_CRYPTO_POINTER_ERROR); }if ((method == NX_CRYPTO_NULL) || (crypto_metadata == NX_CRYPTO_NULL)) { ... } /* Verify the metadata addrsss is 4-byte aligned. */ if((((ULONG)crypto_metadata) & 0x3) != 0) { return(NX_CRYPTO_METADATA_UNALIGNED); }if ((((ULONG)crypto_metadata) & 0x3) != 0) { ... } if(crypto_metadata_size < sizeof(NX_CRYPTO_HKDF)) { return(NX_CRYPTO_INVALID_BUFFER_SIZE); }if (crypto_metadata_size < sizeof(NX_CRYPTO_HKDF)) { ... } hkdf = (NX_CRYPTO_HKDF *)crypto_metadata; /* Initialize IKM with key data. */ hkdf->nx_crypto_hkdf_ikm = key; hkdf->nx_crypto_hkdf_ikm_length = (key_size_in_bits << 3); /* Initialize HMAC and HASH methods. */ hkdf->nx_crypto_hmac_method = NX_CRYPTO_NULL; hkdf->nx_crypto_hash_method = NX_CRYPTO_NULL; return(NX_CRYPTO_SUCCESS); }{ ... } ... /**************************************************************************/ /* */ /* FUNCTION RELEASE */ /* */ /* _nx_crypto_method_hkdf_cleanup PORTABLE C */ /* 6.1 */ /* AUTHOR */ /* */ /* Timothy Stapko, Microsoft Corporation */ /* */ /* DESCRIPTION */ /* */ /* This function cleans up the crypto metadata for the HKDF operation. */ /* */ /* INPUT */ /* */ /* crypto_metadata Crypto metadata */ /* */ /* OUTPUT */ /* */ /* status Completion status */ /* */ /* CALLS */ /* */ /* NX_CRYPTO_MEMSET Set the memory */ /* */ /* CALLED BY */ /* */ /* Application Code */ /* */ /* RELEASE HISTORY */ /* */ /* DATE NAME DESCRIPTION */ /* */ /* 05-19-2020 Timothy Stapko Initial Version 6.0 */ /* 09-30-2020 Timothy Stapko Modified comment(s), */ /* resulting in version 6.1 */ /* */... /**************************************************************************/ NX_CRYPTO_KEEP UINT _nx_crypto_method_hkdf_cleanup(VOID *crypto_metadata) { #ifdef NX_SECURE_KEY_CLEAR NX_CRYPTO_METHOD *hmac_method; NX_CRYPTO_HKDF *hkdf; UINT status;/* ... */ #endif NX_CRYPTO_STATE_CHECK #ifdef NX_SECURE_KEY_CLEAR if (!crypto_metadata) return (NX_CRYPTO_SUCCESS); /* Clear the HMAC state. */ hkdf = (NX_CRYPTO_HKDF *)crypto_metadata; hmac_method = hkdf->nx_crypto_hmac_method; if(hmac_method) { status = hmac_method -> nx_crypto_cleanup(hmac_method); if (status != NX_CRYPTO_SUCCESS) { return(status); }if (status != NX_CRYPTO_SUCCESS) { ... } }if (hmac_method) { ... } /* Clean up the HKDF metadata. */ NX_CRYPTO_MEMSET(crypto_metadata, 0, sizeof(NX_CRYPTO_HKDF));/* ... */ #else NX_CRYPTO_PARAMETER_NOT_USED(crypto_metadata); #endif/* NX_SECURE_KEY_CLEAR */ return(NX_CRYPTO_SUCCESS); }{ ... } ... /**************************************************************************/ /* */ /* FUNCTION RELEASE */ /* */ /* _nx_crypto_method_hkdf_operation PORTABLE C */ /* 6.1 */ /* AUTHOR */ /* */ /* Timothy Stapko, Microsoft Corporation */ /* */ /* DESCRIPTION */ /* */ /* This function provides the generic NetX Crypto API for the HKDF */ /* operation. */ /* */ /* INPUT */ /* */ /* op Operation Type */ /* Encrypt, Decrypt, Authenticate*/ /* handler Pointer to crypto context */ /* key Pointer to key */ /* key_size_in_bits Length of key size in bits */ /* input Input Stream */ /* input_length_in_byte Input Stream Length */ /* iv_ptr Initialized Vector */ /* output Output Stream */ /* output_length_in_byte Output Stream Length */ /* crypto_metadata Metadata area */ /* crypto_metadata_size Size of the metadata area */ /* packet_ptr Pointer to packet */ /* nx_crypto_hw_process_callback Callback function pointer */ /* */ /* OUTPUT */ /* */ /* status Completion status */ /* */ /* CALLS */ /* */ /* _nx_crypto_hkdf_extract Calculate the HKDF key */ /* _nx_crypto_hkdf_expand Generate HKDF key material */ /* */ /* CALLED BY */ /* */ /* Application Code */ /* */ /* RELEASE HISTORY */ /* */ /* DATE NAME DESCRIPTION */ /* */ /* 05-19-2020 Timothy Stapko Initial Version 6.0 */ /* 09-30-2020 Timothy Stapko Modified comment(s), improved */ /* buffer length verification, */ /* verified memcpy use cases, */ /* resulting in version 6.1 */ /* */... /**************************************************************************/ NX_CRYPTO_KEEP UINT _nx_crypto_method_hkdf_operation(UINT op, /* Encrypt, Decrypt, Authenticate */ VOID *handle, /* Crypto handler */ struct NX_CRYPTO_METHOD_STRUCT *method, UCHAR *key, NX_CRYPTO_KEY_SIZE key_size_in_bits, UCHAR *input, ULONG input_length_in_byte, UCHAR *iv_ptr, UCHAR *output, ULONG output_length_in_byte, VOID *crypto_metadata, ULONG crypto_metadata_size, VOID *packet_ptr, VOID (*nx_crypto_hw_process_callback)(VOID *packet_ptr, UINT status)) { NX_CRYPTO_HKDF *hkdf; UINT status; NX_CRYPTO_PARAMETER_NOT_USED(handle); NX_CRYPTO_PARAMETER_NOT_USED(iv_ptr); NX_CRYPTO_PARAMETER_NOT_USED(packet_ptr); NX_CRYPTO_PARAMETER_NOT_USED(nx_crypto_hw_process_callback); NX_CRYPTO_STATE_CHECK /* Verify the metadata addrsss is 4-byte aligned. */ if((method == NX_CRYPTO_NULL) || (crypto_metadata == NX_CRYPTO_NULL) || ((((ULONG)crypto_metadata) & 0x3) != 0)) { return(NX_CRYPTO_POINTER_ERROR); }if ((method == NX_CRYPTO_NULL) || (crypto_metadata == NX_CRYPTO_NULL) || ((((ULONG)crypto_metadata) & 0x3) != 0)) { ... } if(crypto_metadata_size < sizeof(NX_CRYPTO_HKDF)) { return(NX_CRYPTO_INVALID_BUFFER_SIZE); }if (crypto_metadata_size < sizeof(NX_CRYPTO_HKDF)) { ... } /* Get our control block for HKDF. */ hkdf = (NX_CRYPTO_HKDF *)(crypto_metadata); status = NX_CRYPTO_SUCCESS; switch (op) { case NX_CRYPTO_HKDF_SET_HMAC: hkdf->nx_crypto_hmac_method = method; if(hkdf->nx_crypto_hash_method != NX_CRYPTO_NULL) { /* Set the HMAC hash method. */ status = hkdf->nx_crypto_hmac_method->nx_crypto_operation(NX_CRYPTO_HMAC_SET_HASH, NX_CRYPTO_NULL, hkdf->nx_crypto_hash_method, NX_CRYPTO_NULL, 0, NX_CRYPTO_NULL, 0, NX_CRYPTO_NULL, NX_CRYPTO_NULL, 0, hkdf->nx_crypto_hmac_metadata, sizeof(hkdf->nx_crypto_hmac_metadata), NX_CRYPTO_NULL, NX_CRYPTO_NULL); }if (hkdf->nx_crypto_hash_method != NX_CRYPTO_NULL) { ... } break;case NX_CRYPTO_HKDF_SET_HMAC: case NX_CRYPTO_HKDF_SET_HASH: hkdf->nx_crypto_hash_method = method; if(hkdf->nx_crypto_hmac_method != NX_CRYPTO_NULL) { /* Set the HMAC hash method. */ status = hkdf->nx_crypto_hmac_method->nx_crypto_operation(NX_CRYPTO_HMAC_SET_HASH, NX_CRYPTO_NULL, method, NX_CRYPTO_NULL, 0, NX_CRYPTO_NULL, 0, NX_CRYPTO_NULL, NX_CRYPTO_NULL, 0, hkdf->nx_crypto_hmac_metadata, sizeof(hkdf->nx_crypto_hmac_metadata), NX_CRYPTO_NULL, NX_CRYPTO_NULL); }if (hkdf->nx_crypto_hmac_method != NX_CRYPTO_NULL) { ... } break;case NX_CRYPTO_HKDF_SET_HASH: case NX_CRYPTO_HKDF_SET_PRK: if(key == NX_CRYPTO_NULL) { return(NX_CRYPTO_POINTER_ERROR); }if (key == NX_CRYPTO_NULL) { ... } if ((key_size_in_bits >> 3) > sizeof(hkdf->nx_crypto_hkdf_prk)) { return(NX_CRYPTO_SIZE_ERROR); }if ((key_size_in_bits >> 3) > sizeof(hkdf->nx_crypto_hkdf_prk)) { ... } /* Set the PRK and return. */ NX_CRYPTO_MEMCPY(hkdf->nx_crypto_hkdf_prk, key, (key_size_in_bits >> 3)); /* Use case of memcpy is verified. */ hkdf->nx_crypto_hkdf_prk_size = (key_size_in_bits >> 3); break;case NX_CRYPTO_HKDF_SET_PRK: case NX_CRYPTO_HKDF_EXTRACT: if(key == NX_CRYPTO_NULL) { return(NX_CRYPTO_POINTER_ERROR); }if (key == NX_CRYPTO_NULL) { ... } if(hkdf->nx_crypto_hash_method == NX_CRYPTO_NULL || hkdf->nx_crypto_hmac_method == NX_CRYPTO_NULL) { return(NX_CRYPTO_METHOD_INITIALIZATION_FAILURE); }if (hkdf->nx_crypto_hash_method == NX_CRYPTO_NULL || hkdf->nx_crypto_hmac_method == NX_CRYPTO_NULL) { ... } /* Key is our "salt". The IKM should have been passed in the init function.*/ hkdf->nx_crypto_hkdf_salt = key; hkdf->nx_crypto_hkdf_salt_length = (key_size_in_bits >> 3); /* Initialize IKM with input data. */ hkdf->nx_crypto_hkdf_ikm = input; hkdf->nx_crypto_hkdf_ikm_length = input_length_in_byte; /* Our output size is the output size of the hash. */ hkdf->nx_crypto_hkdf_prk_size = hkdf->nx_crypto_hmac_method->nx_crypto_block_size_in_bytes; status = _nx_crypto_hkdf_extract(hkdf); if(status == NX_CRYPTO_SUCCESS) { if (output_length_in_byte < hkdf->nx_crypto_hkdf_prk_size) { return(NX_CRYPTO_SIZE_ERROR); }if (output_length_in_byte < hkdf->nx_crypto_hkdf_prk_size) { ... } /* Copy the PRK into output. */ NX_CRYPTO_MEMCPY(output, hkdf->nx_crypto_hkdf_prk, hkdf->nx_crypto_hkdf_prk_size); /* Use case of memcpy is verified. */ }if (status == NX_CRYPTO_SUCCESS) { ... } break; case NX_CRYPTO_HKDF_EXTRACT: case NX_CRYPTO_HKDF_EXPAND: if(key == NX_CRYPTO_NULL) { return(NX_CRYPTO_POINTER_ERROR); }if (key == NX_CRYPTO_NULL) { ... } if(hkdf->nx_crypto_hash_method == NX_CRYPTO_NULL || hkdf->nx_crypto_hmac_method == NX_CRYPTO_NULL) { return(NX_CRYPTO_METHOD_INITIALIZATION_FAILURE); }if (hkdf->nx_crypto_hash_method == NX_CRYPTO_NULL || hkdf->nx_crypto_hmac_method == NX_CRYPTO_NULL) { ... } /* Key is our "info". The PRK should have been initialized by the call to NX_CRYPTO_HKDF_EXTRACT.*/ hkdf->nx_crypto_hkdf_info = key; hkdf->nx_crypto_hkdf_info_size = (key_size_in_bits >> 3); status = _nx_crypto_hkdf_expand(hkdf, output, output_length_in_byte); break;case NX_CRYPTO_HKDF_EXPAND: default: break;default }switch (op) { ... } return(status); }{ ... } ... /**************************************************************************/ /* */ /* FUNCTION RELEASE */ /* */ /* _nx_crypto_method_hkdf_extract PORTABLE C */ /* 6.1 */ /* AUTHOR */ /* */ /* Timothy Stapko, Microsoft Corporation */ /* */ /* DESCRIPTION */ /* */ /* This function performs the HKDF-extract operation detailed in RFC */ /* 5869. The output key is placed in the HKDF structure passed in. */ /* */ /* INPUT */ /* */ /* hkdf HKDF structure */ /* */ /* OUTPUT */ /* */ /* status Completion status */ /* */ /* CALLS */ /* */ /* [hash method] Perform selected HMAC hash */ /* */ /* CALLED BY */ /* */ /* Application Code */ /* */ /* RELEASE HISTORY */ /* */ /* DATE NAME DESCRIPTION */ /* */ /* 05-19-2020 Timothy Stapko Initial Version 6.0 */ /* 09-30-2020 Timothy Stapko Modified comment(s), */ /* resulting in version 6.1 */ /* */... /**************************************************************************/ UINT _nx_crypto_hkdf_extract(NX_CRYPTO_HKDF *hkdf) { UINT status; UINT hash_size; /* the length of hmac output */ UCHAR *salt; UINT salt_len; UCHAR *ikm; UINT ikm_len; UCHAR *metadata; UINT metadata_size; UCHAR *hmac_output; VOID *handler = NX_CRYPTO_NULL; NX_CRYPTO_METHOD *hmac_method = hkdf -> nx_crypto_hmac_method; NX_CRYPTO_STATE_CHECK /* From RFC 5869: * HKDF-Extract(salt, IKM) -> PRK * * Options: * Hash a hash function; HashLen denotes the length of the * hash function output in octets * * Inputs: * salt optional salt value (a non-secret random value); * if not provided, it is set to a string of HashLen zeros. * IKM input keying material * * Output: * PRK a pseudorandom key (of HashLen octets) * * The output PRK is calculated as follows: * * PRK = HMAC-Hash(salt, IKM) * *//* ... */ /* Validate pointers. */ if (hmac_method == NX_CRYPTO_NULL || hmac_method -> nx_crypto_operation == NX_CRYPTO_NULL || hmac_method -> nx_crypto_cleanup == NX_CRYPTO_NULL || hkdf->nx_crypto_hash_method == NX_CRYPTO_NULL) { return(NX_CRYPTO_INVALID_PARAMETER); }if (hmac_method == NX_CRYPTO_NULL || hmac_method -> nx_crypto_operation == NX_CRYPTO_NULL || hmac_method -> nx_crypto_cleanup == NX_CRYPTO_NULL || hkdf->nx_crypto_hash_method == NX_CRYPTO_NULL) { ... } /* Initialize temporary variables. */ salt = hkdf->nx_crypto_hkdf_salt; salt_len = hkdf->nx_crypto_hkdf_salt_length; ikm = hkdf->nx_crypto_hkdf_ikm; ikm_len = hkdf->nx_crypto_hkdf_ikm_length; hash_size = hkdf -> nx_crypto_hash_method -> nx_crypto_ICV_size_in_bits >> 3; metadata = hkdf->nx_crypto_hmac_metadata; metadata_size = sizeof(hkdf->nx_crypto_hmac_metadata); hmac_output = hkdf->nx_crypto_hkdf_prk; /* Make sure we can store our output key. */ if (hash_size > sizeof(hkdf->nx_crypto_hkdf_prk)) { return(NX_CRYPTO_INVALID_PARAMETER); }if (hash_size > sizeof(hkdf->nx_crypto_hkdf_prk)) { ... } /* Assign the output size to our HKDF structure. */ hkdf->nx_crypto_hkdf_prk_size = hash_size; /* Initialize hash method (check key sizes, etc.). */ if (hmac_method -> nx_crypto_init) { status = hmac_method -> nx_crypto_init(hmac_method, salt, (NX_CRYPTO_KEY_SIZE)(salt_len << 3), &handler, metadata, metadata_size); if(status != NX_CRYPTO_SUCCESS) { return(status); }if (status != NX_CRYPTO_SUCCESS) { ... } }if (hmac_method -> nx_crypto_init) { ... } /* Generate the output PRK. */ status = hmac_method -> nx_crypto_operation(NX_CRYPTO_AUTHENTICATE, handler, hmac_method, salt, (NX_CRYPTO_KEY_SIZE)(salt_len << 3), ikm, ikm_len, NX_CRYPTO_NULL, hmac_output, hash_size, metadata, metadata_size, NX_CRYPTO_NULL, NX_CRYPTO_NULL); return(status); }{ ... } .../**************************************************************************/ /* */ /* FUNCTION RELEASE */ /* */ /* _nx_crypto_method_hkdf_expand PORTABLE C */ /* 6.1 */ /* AUTHOR */ /* */ /* Timothy Stapko, Microsoft Corporation */ /* */ /* DESCRIPTION */ /* */ /* This function performs the HKDF-expand operation detailed in RFC */ /* 5869. The hdkf parameter contains the input key (PRK) and other */ /* parameters needed to generate the desired output data. */ /* */ /* INPUT */ /* */ /* hkdf HKDF structure */ /* */ /* OUTPUT */ /* */ /* status Completion status */ /* */ /* CALLS */ /* */ /* [hash method] Perform selected HMAC hash */ /* */ /* CALLED BY */ /* */ /* Application Code */ /* */ /* RELEASE HISTORY */ /* */ /* DATE NAME DESCRIPTION */ /* */ /* 05-19-2020 Timothy Stapko Initial Version 6.0 */ /* 09-30-2020 Timothy Stapko Modified comment(s), improved */ /* buffer length verification, */ /* verified memcpy use cases, */ /* resulting in version 6.1 */ /* */... /**************************************************************************/ UINT _nx_crypto_hkdf_expand(NX_CRYPTO_HKDF *hkdf, UCHAR *output, UINT desired_length) { UINT offset; UINT N_count; UINT hash_size; /* the length of hmac output */ UCHAR *prk; UINT prk_len; UCHAR *info; UINT info_len; UCHAR *metadata; UINT metadata_size; VOID *handler = NX_CRYPTO_NULL; UINT output_len; /* T(i) */ UCHAR *temp_T; UINT temp_T_size, T_len, T_bytes_to_hash; UINT i; UINT status; NX_CRYPTO_METHOD *hmac_method = hkdf -> nx_crypto_hmac_method; NX_CRYPTO_STATE_CHECK /* From RFC 5869: * HKDF-Expand(PRK, info, L) -> OKM * * Options: * Hash a hash function; HashLen denotes the length of the * hash function output in octets * Inputs: * PRK a pseudorandom key of at least HashLen octets * (usually, the output from the extract step) * info optional context and application specific information * (can be a zero-length string) * L length of output keying material in octets * (<= 255*HashLen) * * Output: * OKM output keying material (of L octets) * * The output OKM is calculated as follows: * * N = ceil(L/HashLen) * T = T(1) | T(2) | T(3) | ... | T(N) * OKM = first L octets of T * * where: * T(0) = empty string (zero length) * T(1) = HMAC-Hash(PRK, T(0) | info | 0x01) * T(2) = HMAC-Hash(PRK, T(1) | info | 0x02) * T(3) = HMAC-Hash(PRK, T(2) | info | 0x03) * ... * * (where the constant concatenated to the end of each T(n) is a * single octet.) * *//* ... */ /* Validate pointers. */ if (hmac_method == NX_CRYPTO_NULL || hmac_method -> nx_crypto_operation == NX_CRYPTO_NULL || hmac_method -> nx_crypto_cleanup == NX_CRYPTO_NULL || hkdf->nx_crypto_hash_method == NX_CRYPTO_NULL || output == NX_CRYPTO_NULL) { return(NX_CRYPTO_INVALID_PARAMETER); }if (hmac_method == NX_CRYPTO_NULL || hmac_method -> nx_crypto_operation == NX_CRYPTO_NULL || hmac_method -> nx_crypto_cleanup == NX_CRYPTO_NULL || hkdf->nx_crypto_hash_method == NX_CRYPTO_NULL || output == NX_CRYPTO_NULL) { ... } /* Initialize temporary variables. */ prk = hkdf->nx_crypto_hkdf_prk; prk_len = hkdf->nx_crypto_hkdf_prk_size; info = hkdf->nx_crypto_hkdf_info; info_len = hkdf->nx_crypto_hkdf_info_size; temp_T = hkdf->nx_crypto_hkdf_temp_T; temp_T_size = sizeof(hkdf->nx_crypto_hkdf_temp_T); hash_size = hkdf-> nx_crypto_hash_method -> nx_crypto_ICV_size_in_bits >> 3; metadata = hkdf->nx_crypto_hmac_metadata; metadata_size = sizeof(hkdf->nx_crypto_hmac_metadata); /* Assign the output size to our HKDF structure. */ hkdf->nx_crypto_hkdf_prk_size = hash_size; /* Assign T(0), the empty string. */ NX_CRYPTO_MEMSET(temp_T, 0, temp_T_size); T_len = 0; /* Get our L count for our loop. */ N_count = 1 + ((desired_length) / hash_size); /* Loop through T(i) to calculate output material (OKM). * NOTE: We start at 1 so the counter is correct. Add one * to N_count to get the full amount of data. *//* ... */ for (i = 1; i < N_count + 1; ++i) { if ((T_len + info_len + 1) > temp_T_size) { return(NX_CRYPTO_SIZE_ERROR); }if ((T_len + info_len + 1) > temp_T_size) { ... } /* Concatenate T(i-1) (in temp_T after the hash above), info, and counter octet to feed into digest. */ NX_CRYPTO_MEMCPY(&temp_T[T_len], info, info_len); /* Use case of memcpy is verified. */ /* Concatenate counter octet. */ temp_T[T_len + info_len] = (UCHAR)(i & 0xFF); /* Initialize hash method. */ if (hmac_method -> nx_crypto_init) { status = hmac_method -> nx_crypto_init(hmac_method, prk, (NX_CRYPTO_KEY_SIZE)(prk_len << 3), &handler, metadata, metadata_size); if (status != NX_CRYPTO_SUCCESS) { return(status); }if (status != NX_CRYPTO_SUCCESS) { ... } }if (hmac_method -> nx_crypto_init) { ... } /* The number of bytes we want to hash is a combination of T_len (0 or <hash size>) the length of "info", and add 1 for the counter octet. *//* ... */ T_bytes_to_hash = T_len + info_len + 1; /* Calculate T(i) = HMAC(PRK, T(i-1) | info | i) */ status = hmac_method -> nx_crypto_operation(NX_CRYPTO_AUTHENTICATE, handler, hmac_method, prk, (NX_CRYPTO_KEY_SIZE)(prk_len << 3), temp_T, T_bytes_to_hash, NX_CRYPTO_NULL, temp_T, temp_T_size, metadata, metadata_size, NX_CRYPTO_NULL, NX_CRYPTO_NULL); if (status != NX_CRYPTO_SUCCESS) { return(status); }if (status != NX_CRYPTO_SUCCESS) { ... } /* Updated the length of T(i) */ T_len = hash_size; /* Get our output offset. */ offset = (i - 1) * hash_size; /* Output block is the size of the digest unless the remaining desired length is smaller than the digest length. *//* ... */ if ((desired_length - offset) < hash_size) { output_len = (desired_length - offset); }if ((desired_length - offset) < hash_size) { ... } else { output_len = hash_size; }else { ... } /* Make sure we only copy the desired data length into the output. */ if (hash_size > desired_length) { output_len = desired_length; }if (hash_size > desired_length) { ... } /* Copy T(i) into output. */ NX_CRYPTO_MEMCPY(&output[offset], temp_T, output_len); /* Use case of memcpy is verified. */ }for (i = 1; i < N_count + 1; ++i) { ... } return(NX_CRYPTO_SUCCESS); }{ ... } ...