1 files changed, 418 insertions, 0 deletions
diff --git a/src/noscryptutil.c b/src/noscryptutil.c
new file mode 100644
index 0000000..b7723cb
--- /dev/null
+++ b/src/noscryptutil.c
@@ -0,0 +1,418 @@
+/*
+* Copyright (c) 2024 Vaughn Nugent
+*
+* Package: noscrypt
+* File: noscryptutil.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/.
+*/
+
+
+#include <noscryptutil.h>
+#include "nc-util.h"
+#include "nc-crypto.h"
+
+/*
+* Validation macros
+*/
+
+#ifdef NC_EXTREME_COMPAT
+	#error "Utilities library must be disabled when using extreme compat mode"
+#endif /* NC_EXTREME_COMPAT */
+
+#include <stdlib.h>
+#include <math.h>
+
+#define _nc_mem_free(x) if(x != NULL) { free(x); x = NULL; }
+#define _nc_mem_alloc(elements, size) calloc(elements, size);
+
+#ifndef NC_INPUT_VALIDATION_OFF
+	#define CHECK_INVALID_ARG(x, argPos) if(x == NULL) return NCResultWithArgPosition(E_INVALID_ARG, argPos);
+	#define CHECK_NULL_ARG(x, argPos) if(x == NULL) return NCResultWithArgPosition(E_NULL_PTR, argPos);
+	#define CHECK_ARG_RANGE(x, min, max, argPos) if(x < min || x > max) return NCResultWithArgPosition(E_ARGUMENT_OUT_OF_RANGE, argPos);
+#else
+	/* empty macros */
+	#define CHECK_INVALID_ARG(x)
+	#define CHECK_NULL_ARG(x, argPos) 
+	#define CHECK_ARG_RANGE(x, min, max, argPos) 
+#endif /* !NC_DISABLE_INPUT_VALIDATION */
+
+
+/* performs a log2 on integer types */
+#define _math_int_log2(x)	(int32_t)log2((double)x)
+
+#define MIN_PADDING_SIZE		0x20
+#define NIP44_VERSION_SIZE		0x01
+#define NIP44_PT_LEN_SIZE		0x02
+
+/* Currently were on nip44 version 2 */
+const static uint8_t Nip44VersionValue = 0x02;
+
+typedef struct nc_util_enc_buffer_state 
+{
+	uint8_t* ciphertext;
+	uint32_t ciphertextSize;
+
+} NCCipherTextOutState;
+
+struct nc_util_enc_struct {
+	
+	/* Dynamically allocated during initialization */
+	NCCipherTextOutState* outState;
+
+	const uint8_t* plaintext;
+	
+	uint32_t plaintextSize;
+
+	NCEncryptionArgs encArgs;
+};
+
+static _nc_fn_inline int32_t _calcNip44PtPadding(int32_t plaintextSize)
+{
+	int32_t chunk, nextPower, factor;
+
+	/*
+	* Taken from https://github.com/nostr-protocol/nips/blob/master/44.md
+	*
+	* I believe the idea is to add consisten padding for some better 
+	* disgusing of the plainText data.
+	*/
+
+	if (plaintextSize <= MIN_PADDING_SIZE)
+	{
+		return MIN_PADDING_SIZE;
+	}
+
+	nextPower = _math_int_log2(plaintextSize - 1);
+
+	nextPower += 1;
+
+	nextPower = 1 << nextPower;
+
+	if (nextPower <= 256)
+	{
+		chunk = 32;
+	}
+	else 
+	{
+		chunk = nextPower / 8;
+	}
+	
+	factor = plaintextSize - 1;
+
+	factor /= chunk;
+
+	factor += 1;
+
+	return chunk * factor;
+}
+
+static _nc_fn_inline int32_t _calcNip44TotalOutSize(int32_t inputSize)
+{
+	int32_t bufferSize;
+
+	/*
+	* Buffer size for nip44 is calculated as follows:
+	*   1 byte for the version
+	*   32 bytes for the nonce
+	*   2 bytes for the length of the plainText
+	*   ... padding size
+	*   32 bytes for the MAC
+	*/
+
+	bufferSize = NIP44_VERSION_SIZE;
+
+	bufferSize += NC_ENCRYPTION_NONCE_SIZE;
+
+	bufferSize += NIP44_PT_LEN_SIZE;
+
+	bufferSize += _calcNip44PtPadding(inputSize);
+
+	bufferSize += NC_ENCRYPTION_MAC_SIZE;
+
+	return bufferSize;
+}
+
+static NCResult _nip44EncryptCompleteCore(
+	const NCContext* libContext,
+	const NCSecretKey* sk,
+	const NCPublicKey* pk,
+	NCEncryptionArgs encArgs,
+	span_t cipherText,
+	span_t plainText
+)
+{
+
+	NCResult result;
+	uint32_t outPos, paddedCtSize;
+	uint16_t ptSize;
+	
+	outPos = 0;
+	
+	DEBUG_ASSERT(encArgs.version == NC_ENC_VERSION_NIP44);
+
+	/* Padded size is required to know how large the CT buffer is for encryption */
+	paddedCtSize = (int32_t)_calcNip44PtPadding((int32_t)plainText.size);
+
+	/* Start by appending the version number */
+	ncSpanAppend(cipherText, &outPos, &Nip44VersionValue, 0x01);
+
+	/* next is nonce data */
+	ncSpanAppend(cipherText, &outPos, encArgs.nonceData, NC_ENCRYPTION_NONCE_SIZE);
+	DEBUG_ASSERT(outPos == 1 + NC_ENCRYPTION_NONCE_SIZE);
+
+	/*
+	* So this is the tricky part. The encryption operation appens directly 
+	* on the ciphertext segment
+	* 
+	* All current implementations allow overlapping input and output buffers
+	* so we can assign the pt segment on the encryption args
+	*/
+
+	/*
+	* Since the message size and padding bytes will get encrypted, 
+	* the buffer should currently point to the start of the encryption segment
+	* 
+	* The size of the data to encrypt is the padded size plus the size of the
+	* plainText size field. 
+	*/
+
+	encArgs.inputData = (cipherText.data + outPos);
+	encArgs.outputData = (cipherText.data + outPos);
+	encArgs.dataSize = paddedCtSize + sizeof(uint16_t);	/* Plaintext + pt size must be encrypted */
+
+	ptSize = (uint16_t)plainText.size;
+
+	/* Can write the plainText size to buffer now */
+	ncSpanAppend(cipherText, &outPos, &ptSize, sizeof(uint16_t));
+
+	/* concat plainText */
+	ncSpanAppend(cipherText, &outPos, plainText.data, plainText.size);
+
+	/* Time to perform encryption operation */
+	result = NCEncrypt(libContext, sk, pk, &encArgs);
+
+	if (result == NC_SUCCESS)
+	{
+
+	}
+}
+
+static NCResult _nip44EncryptCompleteCore(
+	NCUtilEncryptionContext* encCtx,
+	const NCContext* libContext,
+	const NCSecretKey* sk,
+	const NCPublicKey* pk
+)
+{
+	span_t cipherText, plainText;
+
+	/* Set up spans */
+	ncSpanInit(
+		&cipherText, 
+		encCtx->outState->ciphertext,
+		encCtx->outState->ciphertextSize
+	);
+
+	ncSpanInit(
+		&plainText, 
+		encCtx->plaintext, 
+		encCtx->plaintextSize
+	);
+
+	return _nip44EncryptCompleteCore(
+		libContext, 
+		sk, 
+		pk, 
+		encCtx->encArgs, 
+		cipherText, 
+		plainText
+	);
+}
+
+NC_EXPORT NCResult NC_CC NCUtilGetEncryptionPaddedSize(uint32_t encVersion, int32_t plaintextSize)
+{
+	int32_t paddingSize;
+
+	CHECK_ARG_RANGE(plaintextSize, 0, INT32_MAX, 1)
+
+	switch (encVersion)
+	{
+		default:
+			return E_VERSION_NOT_SUPPORTED;
+
+		case NC_ENC_VERSION_NIP04:
+			return plaintextSize;
+
+		case NC_ENC_VERSION_NIP44:
+			paddingSize = _calcNip44PtPadding(plaintextSize);
+
+			DEBUG_ASSERT(paddingSize > 0)
+
+			return (NCResult)(paddingSize);
+	}
+}
+
+NC_EXPORT NCResult NC_CC NCUtilGetEncryptionBufferSize(uint32_t encVersion, int32_t plaintextSize)
+{
+	int32_t totalSize;
+
+	CHECK_ARG_RANGE(plaintextSize, 0, INT32_MAX, 1)
+
+	switch (encVersion)
+	{
+		default:
+			return E_VERSION_NOT_SUPPORTED;
+
+		/*
+		* NIP-04 simply uses AES to 1:1 encrypt the plainText
+		* to ciphertext.
+		*/
+		case NC_ENC_VERSION_NIP04:
+			return plaintextSize;
+
+		case NC_ENC_VERSION_NIP44:
+			totalSize = _calcNip44TotalOutSize(plaintextSize);
+
+			DEBUG_ASSERT(totalSize > 0)
+
+			return (NCResult)(totalSize);
+
+	}
+}
+
+
+NC_EXPORT NCUtilEncryptionContext* NC_CC NCUtilAllocEncryptionContext(uint32_t encVersion)
+{
+	NCUtilEncryptionContext* encCtx;
+
+	/*
+	* Alloc context on heap
+	*/
+	encCtx = (NCUtilEncryptionContext*)_nc_mem_alloc(1, sizeof(NCUtilEncryptionContext));
+
+	if (encCtx != NULL)
+	{
+		encCtx->encArgs.version = encVersion;
+	}
+
+	return encCtx;
+}
+
+NC_EXPORT void NC_CC NCUtilFreeEncryptionContext(NCUtilEncryptionContext* encCtx)
+{
+	if (!encCtx) 
+	{
+		return;
+	}
+
+	/* Free output buffers */
+	_nc_mem_free(encCtx->outState);
+
+	/* context can be released */
+	_nc_mem_free(encCtx);
+}
+
+NC_EXPORT NCResult NC_CC NCUtilInitEncryptionContext(
+	NCUtilEncryptionContext* encCtx,
+	const uint8_t* plainText,
+	uint32_t plainTextSize
+)
+{
+
+	NCResult outputSize;
+	NCCipherTextOutState* output;
+
+	CHECK_NULL_ARG(encCtx, 0)
+	CHECK_NULL_ARG(plainText, 1)
+	CHECK_ARG_RANGE(plainTextSize, 0, INT32_MAX, 2)
+
+	/*
+	* The output state must not have alraedy been allocated
+	*/
+	if (encCtx->outState) 
+	{
+		return E_INVALID_ARG;
+	}
+
+	/*
+	* Calculate the correct output size to store the encryption 
+	* data for the given cipher version
+	*/
+	outputSize = NCUtilGetEncryptionBufferSize(encCtx->encArgs.version, plainTextSize);
+
+	if (outputSize <= 0)
+	{
+		return outputSize;
+	}
+
+	/*Alloc output buffer within the struct */
+	output = (NCCipherTextOutState*)_nc_mem_alloc(sizeof(NCCipherTextOutState) + (int)outputSize, 1);
+
+	if (!output)
+	{
+		return E_OUT_OF_MEMORY;
+	}
+
+	/* set cipertext buffer to end of the structure memory */
+	output->ciphertext = (uint8_t*)(output + 1);
+	output->ciphertextSize = outputSize;
+
+	encCtx->outState = output;
+	encCtx->plaintext = plainText;
+	encCtx->plaintextSize = plainTextSize;
+	
+	return NC_SUCCESS;
+}
+
+NC_EXPORT NCResult NC_CC NCUtilGetEncryptedSize(const NCUtilEncryptionContext* encCtx)
+{
+	CHECK_NULL_ARG(encCtx, 0);
+
+	return (NCResult)(encCtx->outState->ciphertextSize);
+}
+
+NC_EXPORT NCResult NC_CC NCUtilReadEncryptedData(
+	const NCUtilEncryptionContext* encCtx,
+	uint8_t* output,
+	uint32_t outputSize
+)
+{
+	CHECK_NULL_ARG(encCtx, 0)
+	CHECK_NULL_ARG(output, 1)
+	CHECK_ARG_RANGE(outputSize, 0, INT32_MAX, 2)
+
+	if (outputSize < encCtx->outState->ciphertextSize)
+	{
+		return E_OPERATION_FAILED;
+	}
+
+	MEMMOV(output, encCtx->outState->ciphertext, encCtx->outState->ciphertextSize);
+
+	return (NCResult)encCtx->outState->ciphertextSize;
+}
+
+NC_EXPORT NCResult NCUtilSetEncryptionProperty(
+	NCUtilEncryptionContext* ctx,
+	uint32_t property,
+	uint8_t* value,
+	uint32_t valueLen
+)
+{
+	
+	CHECK_NULL_ARG(ctx, 0)
+
+	/* All other arguments are verified */
+	return NCSetEncryptionPropertyEx(&ctx->encArgs, property, value, valueLen);
+}