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Diffstat (limited to 'src/nc-crypto.c')
| -rw-r--r-- | src/nc-crypto.c | 284 |
1 files changed, 284 insertions, 0 deletions
diff --git a/src/nc-crypto.c b/src/nc-crypto.c new file mode 100644 index 0000000..97b59cb --- /dev/null +++ b/src/nc-crypto.c @@ -0,0 +1,284 @@ +/* +* Copyright (c) 2024 Vaughn Nugent +* +* Package: noscrypt +* File: nc-crypto.c +* +* This library is free software; you can redistribute it and/or +* modify it under the terms of the GNU Lesser General Public License +* as published by the Free Software Foundation; either version 2.1 +* of the License, or (at your option) any later version. +* +* This library is distributed in the hope that it will be useful, +* but WITHOUT ANY WARRANTY; without even the implied warranty of +* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +* Lesser General Public License for more details. +* +* You should have received a copy of the GNU Lesser General Public License +* along with noscrypt. If not, see http://www.gnu.org/licenses/. +*/ + +#include "nc-util.h" +#include "nc-crypto.h" +#include "hkdf.h" + +/* +* Functions are not forced inline, just suggested. +* So unless it becomes a performance issue, I will leave +* most/all impl functions inline and let the compiler +* decide. +*/ + +#define _IMPLSTB static _nc_fn_inline + +/* +* Impl .c files may define the following macros for function implementations: +* +* _IMPL_SECURE_ZERO_MEMSET secure memset 0 function +* _IMPL_CHACHA20_CRYPT chacha20 cipher function +* _IMPL_CRYPTO_FIXED_TIME_COMPARE fixed time compare function +* _IMPL_CRYPTO_SHA256_HMAC sha256 hmac function +* _IMPL_CRYPTO_SHA256_DIGEST standard sha256 digest function +* _IMPL_CRYPTO_SHA256_HKDF_EXPAND hkdf expand function +* _IMPL_CRYPTO_SHA256_HKDF_EXTRACT hkdf extract function +* +* Macros are used to allow the preprocessor to select the correct implementation +* or raise errors if no implementation is defined. +* +* Implementation functions can assume inputs have been checked/sanitized by the +* calling function, and should return CSTATUS_OK on success, CSTATUS_FAIL on failure. +*/ + + +/* +* Prioritize embedded builds with mbedtls +*/ +#include "providers/mbedtls.c" + +/* +* Include openssl as an alternative default +* implementation +*/ +#include "providers/openssl.c" + +/* +* Include win32 platform specific fallback support +* using bcrypt. +*/ +#include "providers/bcrypt.c" + +/* +* Handle default implementations of secure +* memset 0 functions for each platform. +*/ +#ifndef _IMPL_SECURE_ZERO_MEMSET + /* only incude bzero if libc version greater than 2.25 */ + #if defined(__GLIBC__) && defined(__GLIBC_MINOR__) && __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 25 + /* + * When using libc, we can use explicit_bzero + * as secure memset implementation. + * + * https://sourceware.org/glibc/manual/2.39/html_mono/libc.html#Erasing-Sensitive-Data + */ + #include <string.h> + extern void explicit_bzero(void* block, size_t len); + #define _IMPL_SECURE_ZERO_MEMSET explicit_bzero + #endif +#endif + +/* +* Finally fall back to monocipher to handle some +* that are not provided by other libraries. +* +* Platform specific opimizations are considered +* "better" than monocypher options, so this is +* added as a last resort. Momocypher is "correct" +* and portable, but not optimized for any specific +* platform. +*/ +#include "providers/monocypher.c" + + +#ifdef _IMPL_CRYPTO_SHA256_HMAC + + /* + * If a library does not provide a HKDF extract function, + * we can just use the HMAC function as a fallback. + * + * This is a fallback because another library may provide + * a more optimized implementation. + */ + + #ifndef _IMPL_CRYPTO_SHA256_HKDF_EXTRACT + + #define _IMPL_CRYPTO_SHA256_HKDF_EXTRACT _fallbackHkdfExtract + + _IMPLSTB cstatus_t _fallbackHkdfExtract(const cspan_t* salt, const cspan_t* ikm, sha256_t prk) + { + return _IMPL_CRYPTO_SHA256_HMAC(salt, ikm, prk); + } + + #endif /* !_IMPL_CRYPTO_SHA256_HKDF_EXTRACT */ + +#endif /* _IMPL_CRYPTO_SHA256_HMAC */ + +/* Fallback for fixed time comparison for all platforms */ +#ifndef _IMPL_CRYPTO_FIXED_TIME_COMPARE + + #pragma message("Warning: No fixed time compare implementation defined, using fallback. This may not be secure on all platforms") + + #define _IMPL_CRYPTO_FIXED_TIME_COMPARE _fallbackFixedTimeCompare + + /* + * This implemntation is a slightly simplified version of + * MBed TLS constant time memcmp function, knowm to be a 32bit + * integer size + */ + + static uint32_t _fallbackFixedTimeCompare(const uint8_t* a, const uint8_t* b, uint32_t size) + { + size_t i; + uint32_t result; + uint8_t O; + volatile const uint8_t* A, * B; + + result = 0; + O = 0; + A = (volatile const uint8_t*)a; + B = (volatile const uint8_t*)b; + + /* Compare each byte */ + for(i = 0; i < size; i++) + { + /* Handle volatile read */ + O |= (A[i] ^ B[i]); + + result |= O; + } + + return result; + } + +#endif /* !_IMPL_CRYPTO_FIXED_TIME_COMPARE */ + + +/* +* Internal function implementations that perform +* basic checking and call the correct implementation +* for the desired crypto impl. +* +* The following functions MUST be assumed to +* perform basic input validation. Since these apis are +* internal, debug asserts are used to ensure the +* function has been used correctly. +*/ + +void ncCryptoSecureZero(void* ptr, uint32_t size) +{ + DEBUG_ASSERT2(ptr != NULL, "Expected ptr to be non-null") + +#ifndef _IMPL_SECURE_ZERO_MEMSET + #error "No secure memset implementation defined" +#endif /* _IMPL_SECURE_ZERO_MEMSET */ + + _IMPL_SECURE_ZERO_MEMSET(ptr, size); +} + +uint32_t ncCryptoFixedTimeComp(const uint8_t* a, const uint8_t* b, uint32_t size) +{ + DEBUG_ASSERT2(a != NULL, "Expected a to be non-null") + DEBUG_ASSERT2(b != NULL, "Expected b to be non-null") + +#ifndef _IMPL_CRYPTO_FIXED_TIME_COMPARE + #error "No fixed time compare implementation defined" +#endif /* !_IMPL_CRYPTO_FIXED_TIME_COMPARE */ + + return _IMPL_CRYPTO_FIXED_TIME_COMPARE(a, b, size); +} + +cstatus_t ncCryptoDigestSha256(const cspan_t* data, sha256_t digestOut32) +{ + /* Debug arg validate */ + DEBUG_ASSERT2(data != NULL && data->data != NULL, "Expected data to be non-null") + DEBUG_ASSERT2(digestOut32 != NULL, "Expected digestOut32 to be non-null") + +#ifndef _IMPL_CRYPTO_SHA256_DIGEST + #error "No SHA256 implementation defined" +#endif /* !_IMPL_CRYPTO_SHA256_DIGEST */ + + return _IMPL_CRYPTO_SHA256_DIGEST(data, digestOut32); +} + +cstatus_t ncCryptoHmacSha256(const cspan_t* key, const cspan_t* data, sha256_t hmacOut32) +{ + /* Debug arg validate */ + DEBUG_ASSERT2(key != NULL && key->data != NULL, "Expected key to be non-null") + DEBUG_ASSERT2(data != NULL && data->data != NULL, "Expected data to be non-null") + DEBUG_ASSERT2(hmacOut32 != NULL && data->data != NULL, "Expected hmacOut32 to be non-null") + +#ifndef _IMPL_CRYPTO_SHA256_HMAC + #error "No SHA256 HMAC implementation defined" +#endif /* !_IMPL_CRYPTO_SHA256_HMAC */ + + return _IMPL_CRYPTO_SHA256_HMAC(key, data, hmacOut32); +} + +cstatus_t ncCryptoSha256HkdfExpand(const cspan_t* prk, const cspan_t* info, span_t* okm) +{ + /* Debug arg validate */ + DEBUG_ASSERT2(prk != NULL && prk->data != NULL, "Expected prk to be non-null") + DEBUG_ASSERT2(info != NULL && info->data != NULL, "Expected info to be non-null") + DEBUG_ASSERT2(okm != NULL && okm->data != NULL, "Expected okm to be non-null") + + /* + * RFC 5869: 2.3 + * "length of output keying material in octets (<= 255 * HashLen)" + * + * important as the counter is 1 byte, so it cannot overflow + */ + + if(okm->size > (uint32_t)(0xFFu * SHA256_DIGEST_SIZE)) + { + return CSTATUS_FAIL; + } + +#ifndef _IMPL_CRYPTO_SHA256_HKDF_EXPAND + #error "No SHA256 HKDF expand implementation defined" +#endif /* !_IMPL_CRYPTO_SHA256_HKDF_EXPAND */ + + return _IMPL_CRYPTO_SHA256_HKDF_EXPAND(prk, info, okm); +} + +cstatus_t ncCryptoSha256HkdfExtract(const cspan_t* salt, const cspan_t* ikm, sha256_t prk) +{ + /* Debug arg validate */ + DEBUG_ASSERT2(salt != NULL, "Expected salt to be non-null") + DEBUG_ASSERT2(ikm != NULL, "Expected ikm to be non-null") + DEBUG_ASSERT2(prk != NULL, "Expected prk to be non-null") + +#ifndef _IMPL_CRYPTO_SHA256_HKDF_EXTRACT + #error "No SHA256 HKDF extract implementation defined" +#endif /* !_IMPL_CRYPTO_SHA256_HKDF_EXTRACT */ + + return _IMPL_CRYPTO_SHA256_HKDF_EXTRACT(salt, ikm, prk); +} + +cstatus_t ncCryptoChacha20( + const uint8_t key[CHACHA_KEY_SIZE], + const uint8_t nonce[CHACHA_NONCE_SIZE], + const uint8_t* input, + uint8_t* output, + uint32_t dataSize +) +{ + DEBUG_ASSERT2(key != NULL, "Expected key to be non-null") + DEBUG_ASSERT2(nonce != NULL, "Expected nonce to be non-null") + DEBUG_ASSERT2(input != NULL, "Expected input to be non-null") + DEBUG_ASSERT2(output != NULL, "Expected output to be non-null") + +#ifndef _IMPL_CHACHA20_CRYPT + #error "No chacha20 implementation defined" +#endif /* !_IMPL_CHACHA20_CRYPT */ + + return _IMPL_CHACHA20_CRYPT(key, nonce, input, output, dataSize); +} |