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Diffstat (limited to 'include/noscrypt.h')
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diff --git a/include/noscrypt.h b/include/noscrypt.h new file mode 100644 index 0000000..68ae8f7 --- /dev/null +++ b/include/noscrypt.h @@ -0,0 +1,562 @@ +/* +* Copyright (c) 2024 Vaughn Nugent +* +* Package: noscrypt +* File: noscrypt.h +* +* 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/. +*/ + +/* +* noscrypt is a an open-source, strict C89 library that performs the basic +* cryptographic operations found in the Nostr protocol. It is designed to be +* portable and easy to use in any C89 compatible environment. It is also designed +*/ + +#pragma once + +#ifndef NOSCRYPT_H +#define NOSCRYPT_H + +#include <stdint.h> +#include <stddef.h> +#include "platform.h" + +/* Set api export calling convention (allow used to override) */ +#ifndef NC_CC + #ifdef _NC_IS_WINDOWS + /* STD for importing to other languages such as .NET */ + #define NC_CC __stdcall + #else + #define NC_CC + #endif +#endif /* !NC_CC */ + +#ifndef NC_EXPORT /* Allow users to disable the export/impoty macro if using source code directly */ + #ifdef NOSCRYPT_EXPORTING + #ifdef _NC_IS_WINDOWS + #define NC_EXPORT __declspec(dllexport) + #else + #define NC_EXPORT __attribute__((visibility("default"))) + #endif /* _NC_IS_WINDOWS */ + #else + #ifdef _NC_IS_WINDOWS + #define NC_EXPORT __declspec(dllimport) + #else + #define NC_EXPORT + #endif /* _NC_IS_WINDOWS */ + #endif /* !NOSCRYPT_EXPORTING */ +#endif /* !NC_EXPORT */ + +/* +* CONSTANTS +*/ +#define BIP340_PUBKEY_HEADER_BYTE 0x02 +#define NIP44_MESSAGE_KEY_SIZE 0x4c /*32 + 12 + 32 = 76 */ +#define NC_ENCRYPTION_NONCE_SIZE 0x20 +#define NC_SEC_KEY_SIZE 0x20 +#define NC_PUBKEY_SIZE 0x20 +#define NC_CONTEXT_ENTROPY_SIZE 0x20 +#define NC_SHARED_SEC_SIZE 0x20 +#define NC_CONV_KEY_SIZE 0x20 +#define NC_HMAC_KEY_SIZE 0x20 +#define NC_ENCRYPTION_MAC_SIZE 0x20 +#define NC_MESSAGE_KEY_SIZE NIP44_MESSAGE_KEY_SIZE + +/* +* From spec +* https://github.com/nostr-protocol/nips/blob/master/44.md#decryption +*/ +#define NIP44_MIN_ENC_MESSAGE_SIZE 0x01 +#define NIP44_MAX_ENC_MESSAGE_SIZE 0xffff + +/* +* ERROR CODES +* +* Error codes are 64bit integers. The lower 8 bits are reserved for +* the error code, and the upper 8 bits are reserved for the argument +* position. +* +* NCResult type is 64bit to also allow for positive return values for +* operations that return a value count. +*/ + +#define NC_ARG_POSITION_OFFSET 0x08 +#define NC_ERROR_CODE_MASK 0xFF + +#define NC_SUCCESS 0x00 +#define E_NULL_PTR -1 +#define E_INVALID_ARG -2 +#define E_INVALID_CONTEXT -3 +#define E_ARGUMENT_OUT_OF_RANGE -4 +#define E_OPERATION_FAILED -5 + +/* A compressed resul/return value, negative values +are failure, 0 is success and positive values are +defined by the operation. +*/ +typedef int64_t NCResult; + +/* + An secp256k1 secret key (aka private key buffer) +*/ +typedef struct secret_key_struct { + + uint8_t key[NC_SEC_KEY_SIZE]; + +} NCSecretKey; + +/* + An x-only secp256k1 public key +*/ +typedef struct xonly_pubkey_struct { + + uint8_t key[NC_PUBKEY_SIZE]; + +} NCPublicKey; + +/* + An opaque full library context object +*/ +typedef struct ctx_struct { + + void* secpCtx; + +} NCContext; + +/* +* The encryption arguments structure. This structure is used to pass +arguments to the encryption and decryption functions. It stores the +data buffers and required nonce used for the stream cipher. +*/ +typedef struct nc_encryption_struct { + + /* The nonce used for the stream cipher. */ + const uint8_t* nonce32; + + /* Writes the hmac key to the buffer during encryption events. + Set to NULL on decryption */ + uint8_t* hmacKeyOut32; + + /* The input data buffer to encrypt/decrypt */ + const uint8_t* inputData; + + /* The output data buffer to write data to */ + uint8_t* outputData; + + /* The size of the data buffers. Buffers must + * be the same size or larger than this value + */ + uint32_t dataSize; + +} NCEncryptionArgs; + +/* +* A structure for Nip44 message authentication code verification. This structure +* is used to pass arguments to the NCVerifyMac and NCVerifyMacEx functions. +*/ +typedef struct nc_mac_verify { + + /* The message authentication code certifying the Nip44 payload */ + const uint8_t* mac32; + + /* The nonce used for the original message encryption */ + const uint8_t* nonce32; + + /* The message payload data */ + const uint8_t* payload; + + /* The size of the payload data */ + uint32_t payloadSize; + +} NCMacVerifyArgs; + + +/* + API FUNCTIONS +*/ + +/* +* A helper function to cast a buffer to a NCSecretKey struct +* @param key The buffer to cast +* @return A pointer to the NCSecretKey struct +*/ +static _nc_fn_inline NCSecretKey* NCToSecKey(uint8_t key[NC_SEC_KEY_SIZE]) +{ + return (NCSecretKey*)key; +} + +/* +* A helper function to cast a buffer to a NCPublicKey struct +* @param key The buffer to cast +* @return A pointer to the NCPublicKey struct +*/ +static _nc_fn_inline NCPublicKey* NCToPubKey(uint8_t key[NC_PUBKEY_SIZE]) +{ + return (NCPublicKey*)key; +} + +static _nc_fn_inline NCResult NCResultWithArgPosition(NCResult err, uint8_t argPosition) +{ + return -(((NCResult)argPosition << NC_ARG_POSITION_OFFSET) | -err); +} + +/* +* Parses an error code and returns the error code and the argument position +that caused the error. +* @param result The error code to parse +* @param argPositionOut A pointer to the argument position to write to +* @return The error code +*/ +static _nc_fn_inline int NCParseErrorCode(NCResult result, uint8_t* argPositionOut) +{ + NCResult asPositive; + int code; + + /* convert result to a positive value*/ + asPositive = -result; + + /* Get the error code from the lower 8 bits and the argument position from the upper 8 bits*/ + code = -(asPositive & NC_ERROR_CODE_MASK); + *argPositionOut = (asPositive >> NC_ARG_POSITION_OFFSET) & 0xFF; + + return code; +} + +/*-------------------------------------- +* LIB CONTEXT API +*/ + +/* +* Runtime check for the size of the context struct to allow +for dynamic allocation when context size structure is not known. +* @return The size of the context struct in bytes +*/ +NC_EXPORT uint32_t NC_CC NCGetContextStructSize(void); +/* +* Initializes a context struct with the given entropy +* @param ctx A pointer to the context structure to initialize +* @param entropy The entropy to initialize the context with +* @return NC_SUCCESS if the operation was successful, otherwise an error code +*/ +NC_EXPORT NCResult NC_CC NCInitContext( + NCContext* ctx, + const uint8_t entropy[NC_CONTEXT_ENTROPY_SIZE] +); +/* +* Reinitializes a context struct with the given +* @param ctx A pointer to the context structure to initialize +* @param entropy The entropy to initialize the context with +* @return NC_SUCCESS if the operation was successful, otherwise an error code +*/ +NC_EXPORT NCResult NC_CC NCReInitContext( + NCContext* ctx, + const uint8_t entropy[NC_CONTEXT_ENTROPY_SIZE] +); + +/* +* Destroys a context struct +* @param ctx A pointer to the existing context structure to destroy +* @return NC_SUCCESS if the operation was successful, otherwise an error code +*/ +NC_EXPORT NCResult NC_CC NCDestroyContext(NCContext* ctx); + + + +/*-------------------------------------- +* HIGH LEVEL SIGNING API +*/ + +/* +* Gets a x-only compressed public key from the given secret key +* @param ctx A pointer to the existing library context +* @param sk A pointer to the secret key +* @param pk A pointer to the compressed public key buffer to write to +* @return NC_SUCCESS if the operation was successful, otherwise an error code +*/ +NC_EXPORT NCResult NC_CC NCGetPublicKey( + const NCContext* ctx, + const NCSecretKey* sk, + NCPublicKey* pk +); +/* +* Validates that a given secret key is valid according to the secp256k1 curve. This +is functionally the same as calling secp256k1_ec_seckey_verify. +* @param ctx A pointer to the existing library context +* @param sk A pointer to the secret key to verify +* @return 1 if the secret key is valid, 0 if it is not, otherwise an error code +*/ +NC_EXPORT NCResult NC_CC NCValidateSecretKey( + const NCContext* ctx, + const NCSecretKey* sk +); + + +/* +* Signs a raw message after computing the sha256 checksum using the +given secret key and writes the signature to the sig64 buffer. +* @param ctx A pointer to the existing library context +* @param sk A pointer to the secret key to sign with +* @param random32 A pointer to the random32 buffer to use for signing +* @param data A pointer to the raw data buffer to sign +* @param dataSize The size of the raw data buffer +* @param sig64 A pointer to the 64byte buffer to write the signature to +* @return NC_SUCCESS if the operation was successful, otherwise an error code +*/ +NC_EXPORT NCResult NC_CC NCSignData( + const NCContext* ctx, + const NCSecretKey* sk, + const uint8_t random32[32], + const uint8_t* data, + const uint32_t dataSize, + uint8_t sig64[64] +); + +/* +* Verifies a signature of a raw data buffer matches the output using the given public key. +* @param ctx A pointer to the existing library context +* @param sig64 The 64byte signature to verify +* @param data A pointer to the raw data buffer to verify +* @param dataSize The size of the raw data buffer +* @param pk A pointer to the the x-only compressed public key (x-only serialized public key) +* @return NC_SUCCESS if the signature could be verified, otherwise an error code +*/ +NC_EXPORT NCResult NC_CC NCVerifyData( + const NCContext* ctx, + const NCPublicKey* pk, + const uint8_t* data, + const uint32_t dataSize, + const uint8_t sig64[64] +); + +/*-------------------------------------- +* EXTENDED SIGNING API +*/ + +/* +* Signs a message using the given secret key and writes the signature to the sig64 buffer +* @param ctx A pointer to the existing library context +* @param sk A pointer to the secret key to sign with +* @param random32 A pointer to the random32 buffer to use for signing +* @param digest32 A pointer to sha256 digest32 to sign +* @param sig64 A pointer to the 64byte buffer to write the signature to +* @return NC_SUCCESS if the operation was successful, otherwise an error code +*/ +NC_EXPORT NCResult NC_CC NCSignDigest( + const NCContext* ctx, + const NCSecretKey* sk, + const uint8_t random32[32], + const uint8_t digest32[32], + uint8_t sig64[64] +); + +/* +* Verifies a signature of a digest32 matches the output using the given public key. +Equivalent to calling secp256k1_schnorrsig_verify. +* @param ctx A pointer to the existing library context +* @param sig64 The 64byte signature to verify +* @param digest32 The digest32 to verify +* @param pk A pointer to the the x-only compressed public key (x-only serialized public key) +* @return NC_SUCCESS if the signature could be verified, otherwise an error code +*/ +NC_EXPORT NCResult NC_CC NCVerifyDigest( + const NCContext* ctx, + const NCPublicKey* pk, + const uint8_t digest32[32], + const uint8_t sig64[64] +); + + + +/*-------------------------------------- +* HIGH LEVEL ENCRYPTION API +*/ + +/* +* NOTES +* +* NIP-44 requires that plaintext/ciphertext must be padded in powers of 2. +* Since this library operates on data at the binary level, and does not do +* ANY runtime heap allocation, it is up to the user to ensure that the +* plaintext/ciphertext buffers are padded properly in The NCryptoData struct +* before calling the encryption/decryption functions. +*/ + +/* +* High level api for encrypting nostr messages using a secret key and a public key. Use +the NCEncryptEx functions for extended encryption functionality +* @param ctx The library context +* @param sk The secret key (the local private key) +* @param pk The compressed public key (x-only serialized public key) the other user's public key +* @param args The encryption arguments +* @return NC_SUCCESS if the operation was successful, otherwise an error code. Use NCParseErrorCode to +the error code and positional argument that caused the error +*/ +NC_EXPORT NCResult NC_CC NCEncrypt( + const NCContext* ctx, + const NCSecretKey* sk, + const NCPublicKey* pk, + NCEncryptionArgs* args +); + +/* +* High level api for decrypting nostr messages using a secret key and a public key. Use +the NCDecryptEx functions for extended decryption functionality. +* @param ctx The library context +* @param sk The secret key (the local private key) +* @param pk The compressed public key (x-only serialized public key) the other user's public key +* @param args The decryption arguments +* @return NC_SUCCESS if the operation was successful, otherwise an error code. Use NCParseErrorCode to +the error code and positional argument that caused the error +*/ +NC_EXPORT NCResult NC_CC NCDecrypt( + const NCContext* ctx, + const NCSecretKey* sk, + const NCPublicKey* pk, + NCEncryptionArgs* args +); + +/* +* High level api for verifying a Nip44 message authentication code using a secret key +and a public key. Use the NCVerifyMacEx functions for extended verification functionality. +* @param ctx A pointer to an existing library context +* @param sk A pointer to the secret key +* @param pk A pointer to the compressed public key (x-only serialized public key) +* @param args A pointer to the mac verification arguments +* @return NC_SUCCESS if the operation was successful, otherwise an error code. Use NCParseErrorCode to +* the error code and positional argument that caused the error +*/ +NC_EXPORT NCResult NC_CC NCVerifyMac( + const NCContext* ctx, + const NCSecretKey* sk, + const NCPublicKey* pk, + NCMacVerifyArgs* args +); + +/*-------------------------------------- +* EXTENDED ENCRYPTION API +*/ + +/* +* Computes a NIP-44 shared secret from a secret key and a public key and +stores it in the sharedPoint buffer. +* @param ctx A pointer to the existing library context +* @param sk The secret key +* @param pk The compressed public key (x-only serialized public key) +* @param sharedPoint The buffer to store write the secret data to +* @return NC_SUCCESS if the operation was successful, otherwise an error code. Use NCParseErrorCode to +the error code and positional argument that caused the error +*/ +NC_EXPORT NCResult NC_CC NCGetSharedSecret( + const NCContext* ctx, + const NCSecretKey* sk, + const NCPublicKey* pk, + uint8_t sharedPoint[NC_SHARED_SEC_SIZE] +); + +/* +* Computes a NIP-44 conversation key from the local secret key and the remote +public key, and stores it in the conversationKey buffer. +* @param ctx A pointer to the existing library context +* @param sk A pointer to the the secret key +* @param pk A pointer to the compressed public key (x-only serialized public key) +* @param conversationKey The buffer to store write the conversation key to +* @return NC_SUCCESS if the operation was successful, otherwise an error code. Use NCParseErrorCode to +the error code and positional argument that caused the error +*/ +NC_EXPORT NCResult NC_CC NCGetConversationKey( + const NCContext* ctx, + const NCSecretKey* sk, + const NCPublicKey* pk, + uint8_t conversationKey[NC_CONV_KEY_SIZE] +); +/* +* Computes a NIP-44 conversation key a shared secret/point, and stores it in the +conversationKey buffer. +* @param ctx A pointer to the existing library context +* @param sharedPoint A pointer to the shared secret/point +* @param conversationKey The buffer to store write the conversation key to +* @return NC_SUCCESS if the operation was successful, otherwise an error code. Use NCParseErrorCode to +the error code and positional argument that caused the error +*/ +NC_EXPORT NCResult NC_CC NCGetConversationKeyEx( + const NCContext* ctx, + const uint8_t sharedPoint[NC_SHARED_SEC_SIZE], + uint8_t conversationKey[NC_CONV_KEY_SIZE] +); + +/* +* Encrypts a message using the given conversation key and writes the encrypted message to the +* output buffer. The output buffer must be at least 99 bytes in size. +* @param ctx A pointer to the existing library context +* @param conversationKey A pointer to the conversation key +* @param args A pointer to the encryption arguments structure +* @return NC_SUCCESS if the operation was successful, otherwise an error code. Use NCParseErrorCode to +the error code and positional argument that caused the error. +*/ +NC_EXPORT NCResult NC_CC NCEncryptEx( + const NCContext* ctx, + const uint8_t conversationKey[NC_CONV_KEY_SIZE], + NCEncryptionArgs* args +); + +/* +* Decrypts a message using the given conversation key and writes the decrypted message to the +* output buffer. +* @param ctx A pointer to the existing library context +* @param conversationKey A pointer to the conversation key +* @param args A pointer to the decryption arguments structure +* @return NC_SUCCESS if the operation was successful, otherwise an error code. Use NCParseErrorCode to +the error code and positional argument that caused the error. +*/ +NC_EXPORT NCResult NC_CC NCDecryptEx( + const NCContext* ctx, + const uint8_t conversationKey[NC_CONV_KEY_SIZE], + NCEncryptionArgs* args +); + +/* +* Verifies a Nip44 message authentication code using the given conversation key. +* @param ctx A pointer to the existing library context +* @param conversationKey A pointer to the conversation key +* @param args A pointer to the mac verification arguments +* @return NC_SUCCESS if the operation was successful, otherwise an error code. Use NCParseErrorCode to +* the error code and positional argument that caused the error. +*/ +NC_EXPORT NCResult NC_CC NCVerifyMacEx( + const NCContext* ctx, + const uint8_t conversationKey[NC_CONV_KEY_SIZE], + NCMacVerifyArgs* args +); + +/* +* Computes a message authentication code for a given payload using the given hmacKey and writes the +* mac to the hmacOut buffer. +* @param ctx A pointer to the existing library context +* @param hmacKey A pointer to the hmac key +* @param payload A pointer to the payload data buffer +* @param payloadSize The size of the payload data buffer +* @param hmacOut A pointer to the buffer to write the mac to +* @return NC_SUCCESS if the operation was successful, otherwise an error code. Use NCParseErrorCode to +* the error code and positional argument that caused the error. +*/ +NC_EXPORT NCResult NCComputeMac( + const NCContext* ctx, + const uint8_t hmacKey[NC_HMAC_KEY_SIZE], + const uint8_t* payload, + uint32_t payloadSize, + uint8_t hmacOut[NC_ENCRYPTION_MAC_SIZE] +); + +#endif /* !NOSCRYPT_H */ |