Push latest changes, patches, and internal upgrades

15 files changed, 469 insertions, 328 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 493b18a..6dad383 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -143,21 +143,6 @@ target_include_directories(${_NC_PROJ_NAME}_static SYSTEM PUBLIC vendor/secp256k
 #
 #############################################
 
-#try to load openssl quietly in order to check for its availability
-find_package(OpenSSL QUIET)
-
-#setup default linking to crypto libraries for certain plaftorms. 
-#Windows defaults to bcrypt, openssl otherwise if installed
-if(CRYPTO_LIB STREQUAL "")	
-  if(MSVC)
-	set(CRYPTO_LIB "bcrypt")
-  elseif(OPENSSL_FOUND)
-	set(CRYPTO_LIB "openssl")
-  endif()
-
-  message(STATUS "No crypto library was specified, defaulting to ${CRYPTO_LIB}")
-endif()
-
 #Include mbedtls if enabled
 if(NC_FETCH_MBEDTLS)
 
@@ -186,6 +171,22 @@ if(NC_FETCH_MBEDTLS)
 
 endif()
 
+#try to load openssl quietly in order to check for its availability
+find_package(OpenSSL QUIET)
+
+#setup default linking to crypto libraries for certain plaftorms. 
+#Windows defaults to bcrypt, openssl otherwise if installed
+if(CRYPTO_LIB STREQUAL "")	
+  if(MSVC)
+	set(CRYPTO_LIB "bcrypt")
+  elseif(OPENSSL_FOUND)
+	set(CRYPTO_LIB "openssl")
+  endif()
+
+  message(STATUS "No crypto library was specified, defaulting to ${CRYPTO_LIB}")
+endif()
+
+
 #if mbedtls linking is enabled target the library
 if(CRYPTO_LIB STREQUAL "mbedtls")
 
diff --git a/Taskfile.yaml b/Taskfile.yaml
index a79921c..93ea182 100644
--- a/Taskfile.yaml
+++ b/Taskfile.yaml
@@ -14,6 +14,7 @@ version: '3'
 
 vars:
   CMAKE_BUILD_DIR: 'build/{{ OS }}'
+  TEST_EXE_NAME: 'nctest'
 
 tasks:
 
@@ -29,14 +30,6 @@ tasks:
      - task: build-internal
        vars: { CMAKE_TEST_STATUS: 'ON', BUILD_CONFIG: 'Debug' }
 
-  build-internal:
-    internal: true
-    cmds:
-     - cmake -S . -B{{.CMAKE_BUILD_DIR}} -DCMAKE_BUILD_TYPE={{.BUILD_CONFIG}} -DNC_BUILD_TESTS={{ .CMAKE_TEST_STATUS }} {{.CLI_ARGS}}
-     - cmake --build {{.CMAKE_BUILD_DIR}} --config {{.BUILD_CONFIG}}
-     - cmd: echo "Build complete. Your files can be found in the {{.CMAKE_BUILD_DIR}} directory"
-       silent: true
-
   #available to users and vnbuild runner
   test:
     desc: "Builds a local copy of the library in a debug configuration, then runs the test executable"
@@ -44,6 +37,37 @@ tasks:
      - task: build-debug
      - cmd: cd {{.CMAKE_BUILD_DIR}} && ctest -C Debug --verbose
   
+  test-mbedtls:
+    desc: "Builds and runs tests for noscrypt using the mbedtls crypto library for the current platform"
+    cmds:
+     - task: build-internal
+       vars: 
+         CMAKE_TEST_STATUS: 'ON'
+         BUILD_CONFIG: 'Debug'
+         CLI_ARGS: '-DNC_FETCH_MBEDTLS=ON {{.CLI_ARGS}}'  #fetches and enabled medtls
+     - cmd: cd {{.CMAKE_BUILD_DIR}} && ctest -C Debug --verbose
+
+  test-dev:
+    desc: "Re-runs compilation phase and test execution"
+    cmds:
+     - task: compile
+       vars: { BUILD_CONFIG: 'Debug' }
+     - cmd: cd {{.CMAKE_BUILD_DIR}} && ctest -C Debug --verbose --output-on-failure
+
+  compile:
+    internal: true
+    cmds:
+      - cmake --build {{.CMAKE_BUILD_DIR}} --config {{.BUILD_CONFIG}}
+
+  build-internal:
+    internal: true
+    cmds:
+     - cmake -S . -B{{.CMAKE_BUILD_DIR}} -DCMAKE_BUILD_TYPE={{.BUILD_CONFIG}} -DNC_BUILD_TESTS={{ .CMAKE_TEST_STATUS }} {{.CLI_ARGS}}
+     - task: compile
+       vars: { BUILD_CONFIG: '{{.BUILD_CONFIG}}' }
+     - cmd: echo "Build complete. Your files can be found in the {{.CMAKE_BUILD_DIR}} directory"
+       silent: true
+
   install:
     desc: "Uses cmake to install the library on your system"
     cmds:
@@ -115,17 +139,26 @@ tasks:
     desc: "Packs up the project source code and creates a tarball in the builds binary directory"
     vars:
       TARGET_SOURCE: '{{.PROJECT_DIR}}/{{.BINARY_DIR}}/{{.PROJECT_NAME}}-src.tgz'
-      SOURCE_FILES: 'CMakeLists.txt src include license tests vendor readme.md Taskfile.yaml'
+      SOURCE_FILES: [ CMakeLists.txt, Taskfile.yaml, src, include, license, tests, vendor, readme.md, CMakePresets.json ]
 
     cmds:
       #tar up the source
-     - tar -czf "{{.TARGET_SOURCE}}" {{.SOURCE_FILES}}  
+     - tar -czf "{{.TARGET_SOURCE}}" {{ .SOURCE_FILES | join " " }}  
  
 #################################
 #
 #       DEV TASKS
 #
 #################################
+
+  dev-gdb-test:
+    platforms: [ linux ]
+    desc: "Starts a new gdb session on the test executable"
+    interactive: true
+    cmds:
+     - task: compile
+       vars: { BUILD_CONFIG: 'Debug' }
+     - cmd: gdb '{{.CMAKE_BUILD_DIR}}/{{.TEST_EXE_NAME}}'
   
   dev-update-deps:
      desc: "Updates vendored projects files (headers mostly) from their source repositories to the latest version"
diff --git a/include/noscrypt.h b/include/noscrypt.h
index 8b39f17..b91bc2b 100644
--- a/include/noscrypt.h
+++ b/include/noscrypt.h
@@ -58,7 +58,7 @@ extern "C" {
 		#ifdef _NC_IS_WINDOWS
 			#define NC_EXPORT __declspec(dllimport)
 		#else
-			#define NC_EXPORT
+			#define NC_EXPORT extern
 		#endif /*  _NC_IS_WINDOWS */
 	#endif /*  !NOSCRYPT_EXPORTING */
 #endif /*  !NC_EXPORT */
diff --git a/include/noscryptutil.h b/include/noscryptutil.h
index 13b9231..a5e460f 100644
--- a/include/noscryptutil.h
+++ b/include/noscryptutil.h
@@ -39,11 +39,13 @@ extern "C" {
 #define E_CIPHER_INVALID_FORMAT			-11
 #define E_CIPHER_BAD_NONCE				-12
 #define E_CIPHER_MAC_INVALID			-13
+#define E_CIPHER_NO_OUTPUT				-14
 
 #define NC_UTIL_CIPHER_MODE_ENCRYPT		0x00u
 #define NC_UTIL_CIPHER_MODE_DECRYPT		0x01u
 #define NC_UTIL_CIPHER_ZERO_ON_FREE		0x02u
 #define NC_UTIL_CIPHER_MAC_NO_VERIFY	0x04u
+#define NC_UTIL_CIPHER_REUSEABLE		0x08u
 
 /*
 * The encryption context structure. This structure is used to store the state 
@@ -166,7 +168,7 @@ NC_EXPORT NCResult NC_CC NCUtilCipherGetFlags(const NCUtilCipherContext* ctx);
 * so the exact same operation should happen if called again.
 */
 NC_EXPORT NCResult NC_CC NCUtilCipherUpdate(
-	const NCUtilCipherContext* encCtx,
+	NCUtilCipherContext* encCtx,
 	const NCContext* libContext,
 	const NCSecretKey* sk,
 	const NCPublicKey* pk
diff --git a/src/hkdf.c b/src/hkdf.c
index cff7d60..ab661de 100644
--- a/src/hkdf.c
+++ b/src/hkdf.c
@@ -42,16 +42,15 @@ static _nc_fn_inline void debugValidateHandler(const struct nc_hkdf_fn_cb_struct
 cstatus_t hkdfExpandProcess(
 	const struct nc_hkdf_fn_cb_struct* handler,
 	void* ctx,
-	const cspan_t* info,
-	span_t* okm
+	cspan_t info,
+	span_t okm
 )
 {
 	cstatus_t result;
-
-	uint8_t counter;
+	cspan_t tSpan, counterSpan;
 	uint32_t tLen, okmOffset;
+	uint8_t counter[1];
 	uint8_t t[HKDF_IN_BUF_SIZE];
-	cspan_t tSpan, counterSpan;
 
 	debugValidateHandler(handler);
 
@@ -59,18 +58,18 @@ cstatus_t hkdfExpandProcess(
 
 	tLen = 0;				/* T(0) is an empty string(zero length) */
 	okmOffset = 0;
-	counter = 1;			/* counter is offset by 1 for init */
+	counter[0] = 1;			/* counter is offset by 1 for init */
 	result = CSTATUS_FAIL;	/* Start in fail state */
 
 	/* counter as a span */
-	ncSpanInitC(&counterSpan, &counter, sizeof(counter));
+	ncSpanInitC(&counterSpan, counter, sizeof(counter));
 
 	/* Compute T(N) = HMAC(prk, T(n-1) | info | n) */
-	while (okmOffset < okm->size)
+	while (okmOffset < okm.size)
 	{
 		ncSpanInitC(&tSpan, t, tLen);
 
-		if (handler->update(ctx, &tSpan) != CSTATUS_OK)
+		if (handler->update(ctx, tSpan) != CSTATUS_OK)
 		{
 			goto Exit;
 		}
@@ -80,7 +79,7 @@ cstatus_t hkdfExpandProcess(
 			goto Exit;
 		}
 
-		if (handler->update(ctx, &counterSpan) != CSTATUS_OK)
+		if (handler->update(ctx, counterSpan) != CSTATUS_OK)
 		{
 			goto Exit;
 		}
@@ -96,18 +95,15 @@ cstatus_t hkdfExpandProcess(
 		}
 
 		/* tlen becomes the hash size or remaining okm size */
-		tLen = HKDF_MIN(okm->size - okmOffset, SHA256_DIGEST_SIZE);
+		tLen = HKDF_MIN(okm.size - okmOffset, SHA256_DIGEST_SIZE);
 
 		DEBUG_ASSERT(tLen <= sizeof(t));
 
-		/* write the T buffer back to okm */
-		ncSpanWrite(*okm, okmOffset, t, tLen);
-
-		/* shift base okm pointer by T */
-		okmOffset += tLen;
+		/* write the T buffer back to okm and advance okmOffset by tLen */
+		ncSpanAppend(okm, &okmOffset, t, tLen);
 
 		/* increment counter */
-		counter++;
+		(*counter)++;
 	}
 
 	result = CSTATUS_OK;	/* HMAC operation completed, so set success */
diff --git a/src/hkdf.h b/src/hkdf.h
index 2e3a55e..50ee6e8 100644
--- a/src/hkdf.h
+++ b/src/hkdf.h
@@ -42,7 +42,7 @@
 
 /* typedefs for hdkf callback functions */
 
-typedef cstatus_t (*hmac_hash_fn)(void* ctx, const cspan_t* data);
+typedef cstatus_t (*hmac_hash_fn)(void* ctx, cspan_t data);
 typedef cstatus_t (*hmac_finish_fn)(void* ctx, sha256_t hmacOut32);
 
 struct nc_hkdf_fn_cb_struct
@@ -54,8 +54,8 @@ struct nc_hkdf_fn_cb_struct
 cstatus_t hkdfExpandProcess(
 	const struct nc_hkdf_fn_cb_struct* handler,
 	void* ctx,
-	const cspan_t* info,
-	span_t* okm
+	cspan_t info,
+	span_t okm
 );
 
 #endif /* !_NC_HKDF_H */
diff --git a/src/nc-crypto.c b/src/nc-crypto.c
index 99c072d..752c9b0 100644
--- a/src/nc-crypto.c
+++ b/src/nc-crypto.c
@@ -134,7 +134,7 @@ _IMPLSTB cstatus_t _dummyAesFunc(
 
 		#define _IMPL_CRYPTO_SHA256_HKDF_EXTRACT		_fallbackHkdfExtract
 
-		_IMPLSTB cstatus_t _fallbackHkdfExtract(const cspan_t* salt, const cspan_t* ikm, sha256_t prk)
+		_IMPLSTB cstatus_t _fallbackHkdfExtract(cspan_t salt, cspan_t ikm, sha256_t prk)
 		{
 			return _IMPL_CRYPTO_SHA256_HMAC(salt, ikm, prk);
 		}
@@ -217,11 +217,11 @@ uint32_t ncCryptoFixedTimeComp(const uint8_t* a, const uint8_t* b, uint32_t size
 	return _IMPL_CRYPTO_FIXED_TIME_COMPARE(a, b, size);
 }
 
-cstatus_t ncCryptoDigestSha256(const cspan_t* data, sha256_t digestOut32)
+cstatus_t ncCryptoDigestSha256(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")
+	DEBUG_ASSERT2(ncSpanIsValidC(data),	"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"
@@ -230,12 +230,12 @@ cstatus_t ncCryptoDigestSha256(const cspan_t* data, sha256_t digestOut32)
 	return _IMPL_CRYPTO_SHA256_DIGEST(data, digestOut32);
 }
 
-cstatus_t ncCryptoHmacSha256(const cspan_t* key, const cspan_t* data, sha256_t hmacOut32)
+cstatus_t ncCryptoHmacSha256(cspan_t key, 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")
+	DEBUG_ASSERT2(ncSpanIsValidC(key),	"Expected key to be non-null")
+	DEBUG_ASSERT2(ncSpanIsValidC(data),	"Expected data to be non-null")
+	DEBUG_ASSERT2(hmacOut32 != NULL,	"Expected hmacOut32 to be non-null")
 
 #ifndef _IMPL_CRYPTO_SHA256_HMAC
 	#error "No SHA256 HMAC implementation defined"
@@ -244,12 +244,12 @@ cstatus_t ncCryptoHmacSha256(const cspan_t* key, const cspan_t* data, sha256_t h
 	return _IMPL_CRYPTO_SHA256_HMAC(key, data, hmacOut32);
 }
 
-cstatus_t ncCryptoSha256HkdfExpand(const cspan_t* prk, const cspan_t* info, span_t* okm)
+cstatus_t ncCryptoSha256HkdfExpand(cspan_t prk, 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")
+	DEBUG_ASSERT2(ncSpanIsValidC(prk),	"Expected prk to be non-null")
+	DEBUG_ASSERT2(ncSpanIsValidC(info),	"Expected info to be non-null")
+	DEBUG_ASSERT2(ncSpanIsValid(okm),	"Expected okm to be non-null")
 
 	/*
 	* RFC 5869: 2.3
@@ -258,7 +258,7 @@ cstatus_t ncCryptoSha256HkdfExpand(const cspan_t* prk, const cspan_t* info, span
 	* important as the counter is 1 byte, so it cannot overflow
 	*/
 
-	if(okm->size > (uint32_t)(0xFFu * SHA256_DIGEST_SIZE))
+	if(okm.size > (uint32_t)(0xFFu * SHA256_DIGEST_SIZE))
 	{
 		return CSTATUS_FAIL;
 	}
@@ -270,12 +270,12 @@ cstatus_t ncCryptoSha256HkdfExpand(const cspan_t* prk, const cspan_t* info, span
 	return _IMPL_CRYPTO_SHA256_HKDF_EXPAND(prk, info, okm);
 }
 
-cstatus_t ncCryptoSha256HkdfExtract(const cspan_t* salt, const cspan_t* ikm, sha256_t prk)
+cstatus_t ncCryptoSha256HkdfExtract(cspan_t salt, 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")
+	DEBUG_ASSERT2(ncSpanIsValidC(salt), "Expected salt to be non-null")
+	DEBUG_ASSERT2(ncSpanIsValidC(ikm),	"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"
diff --git a/src/nc-crypto.h b/src/nc-crypto.h
index 11da6d3..a1545de 100644
--- a/src/nc-crypto.h
+++ b/src/nc-crypto.h
@@ -42,13 +42,13 @@ uint32_t ncCryptoFixedTimeComp(const uint8_t* a, const uint8_t* b, uint32_t size
 
 void ncCryptoSecureZero(void* ptr, uint32_t size);
 
-cstatus_t ncCryptoDigestSha256(const cspan_t* data, sha256_t digestOut32);
+cstatus_t ncCryptoDigestSha256(cspan_t data, sha256_t digestOut32);
 
-cstatus_t ncCryptoHmacSha256(const cspan_t* key, const cspan_t* data, sha256_t hmacOut32);
+cstatus_t ncCryptoHmacSha256(cspan_t key, cspan_t data, sha256_t hmacOut32);
 
-cstatus_t ncCryptoSha256HkdfExpand(const cspan_t* prk, const cspan_t* info, span_t* okm);
+cstatus_t ncCryptoSha256HkdfExpand(cspan_t prk, cspan_t info, span_t okm);
 
-cstatus_t ncCryptoSha256HkdfExtract(const cspan_t* salt, const cspan_t* ikm, sha256_t prk);
+cstatus_t ncCryptoSha256HkdfExtract(cspan_t salt, cspan_t ikm, sha256_t prk);
 
 cstatus_t ncCryptoChacha20(
 	const uint8_t key[CHACHA_KEY_SIZE],
diff --git a/src/nc-util.h b/src/nc-util.h
index d0afe28..2ddfd3f 100644
--- a/src/nc-util.h
+++ b/src/nc-util.h
@@ -102,6 +102,26 @@ typedef struct read_only_memory_span_struct
 	uint32_t size;
 } cspan_t;
 
+static _nc_fn_inline int ncSpanIsValid(span_t span)
+{
+	return span.data != NULL;
+}
+
+static _nc_fn_inline int ncSpanIsValidC(cspan_t span)
+{
+	return span.data != NULL;
+}
+
+static _nc_fn_inline int ncSpanIsValidRange(span_t span, uint32_t offset, uint32_t size)
+{
+	return ncSpanIsValid(span) && offset + size <= span.size;
+}
+
+static _nc_fn_inline int ncSpanIsValidRangeC(cspan_t span, uint32_t offset, uint32_t size)
+{
+	return ncSpanIsValidC(span) && offset + size <= span.size;
+}
+
 static _nc_fn_inline void ncSpanInitC(cspan_t* span, const uint8_t* data, uint32_t size)
 {
 	span->data = data;
@@ -114,9 +134,25 @@ static _nc_fn_inline void ncSpanInit(span_t* span, uint8_t* data, uint32_t size)
 	span->size = size;
 }
 
+static _nc_fn_inline const uint8_t* ncSpanGetOffsetC(cspan_t span, uint32_t offset)
+{
+	DEBUG_ASSERT2(ncSpanIsValidC(span), "Expected span to be non-null");
+	DEBUG_ASSERT2(offset < span.size,	"Expected offset to be less than span size");
+
+	return span.data + offset;
+}
+
+static _nc_fn_inline uint8_t* ncSpanGetOffset(span_t span, uint32_t offset)
+{
+	DEBUG_ASSERT2(ncSpanIsValid(span), "Expected span to be non-null");
+	DEBUG_ASSERT2(offset < span.size, "Expected offset to be less than span size");
+
+	return span.data + offset;
+}
+
 static _nc_fn_inline void ncSpanWrite(span_t span, uint32_t offset, const uint8_t* data, uint32_t size)
 {
-	DEBUG_ASSERT2(span.data != NULL,	"Expected span to be non-null")
+	DEBUG_ASSERT2(ncSpanIsValid(span),	"Expected span to be non-null")
 	DEBUG_ASSERT2(data != NULL,			"Expected data to be non-null")
 	DEBUG_ASSERT2(offset + size <= span.size, "Expected offset + size to be less than span size")
 
@@ -126,7 +162,7 @@ static _nc_fn_inline void ncSpanWrite(span_t span, uint32_t offset, const uint8_
 
 static _nc_fn_inline void ncSpanAppend(span_t span, uint32_t* offset, const uint8_t* data, uint32_t size)
 {
-	DEBUG_ASSERT2(span.data != NULL,	"Expected span to be non-null")
+	DEBUG_ASSERT2(ncSpanIsValid(span),	"Expected span to be non-null")
 	DEBUG_ASSERT2(offset != NULL,		"Expected offset to be non-null")
 	DEBUG_ASSERT2(data != NULL,			"Expected data to be non-null")
 	DEBUG_ASSERT2(*offset + size <= span.size, "Expected offset + size to be less than span size")
@@ -142,7 +178,7 @@ static _nc_fn_inline span_t ncSpanSlice(span_t span, uint32_t offset, uint32_t s
 {
 	span_t slice;
 
-	DEBUG_ASSERT2(span.data != NULL,	"Expected span to be non-null");
+	DEBUG_ASSERT2(ncSpanIsValid(span),	"Expected span to be non-null");
 	DEBUG_ASSERT2(offset + size <= span.size, "Expected offset + size to be less than span size")
 
 	/* Initialize slice, offset input data by the specified offset */
@@ -155,7 +191,7 @@ static _nc_fn_inline cspan_t ncSpanSliceC(cspan_t span, uint32_t offset, uint32_
 {
 	cspan_t slice;
 
-	DEBUG_ASSERT2(span.data != NULL, "Expected span to be non-null");
+	DEBUG_ASSERT2(ncSpanIsValidC(span), "Expected span to be non-null");
 	DEBUG_ASSERT2(offset + size <= span.size, "Expected offset + size to be less than span size")
 
 	/* Initialize slice, offset input data by the specified offset */
@@ -164,5 +200,39 @@ static _nc_fn_inline cspan_t ncSpanSliceC(cspan_t span, uint32_t offset, uint32_
 	return slice;
 }
 
+static _nc_fn_inline void ncSpanCopyC(cspan_t src, span_t dest)
+{
+	DEBUG_ASSERT2(ncSpanIsValidC(src), "Expected span to be non-null");
+	DEBUG_ASSERT2(ncSpanIsValid(dest), "Expected offset + size to be less than span size");
+	DEBUG_ASSERT2(dest.size >= src.size, "Output buffer too small. Overrun detected");
+
+	/* Copy data to span */
+	MEMMOV(dest.data, src.data, src.size);
+}
+
+static _nc_fn_inline void ncSpanCopy(span_t src, span_t dest)
+{
+	cspan_t csrc;
+	
+	ncSpanInitC(&csrc, src.data, src.size);
+	ncSpanCopyC(csrc, dest);
+}
+
+static _nc_fn_inline void ncSpanReadC(cspan_t src, uint8_t* dest, uint32_t size)
+{
+	span_t dsts;
+
+	ncSpanInit(&dsts, dest, size);
+	ncSpanCopyC(src, dsts);
+}
+
+static _nc_fn_inline void ncSpanRead(span_t src, uint8_t* dest, uint32_t size)
+{
+	cspan_t srcs;
+
+	ncSpanInitC(&srcs, src.data, src.size);
+	ncSpanReadC(srcs, dest, size);
+}
+
 
 #endif /* !_NC_UTIL_H */
\ No newline at end of file
diff --git a/src/noscrypt.c b/src/noscrypt.c
index f3c28cb..46b3d65 100644
--- a/src/noscrypt.c
+++ b/src/noscrypt.c
@@ -244,7 +244,9 @@ static _nc_fn_inline NCResult _computeConversationKey(
 	ncSpanInitC(&saltSpan, Nip44ConstantSalt, sizeof(Nip44ConstantSalt));
 	ncSpanInitC(&ikmSpan, sharedSecret->value, NC_SHARED_SEC_SIZE);
 	
-	return ncCryptoSha256HkdfExtract(&saltSpan, &ikmSpan, ck->value) == CSTATUS_OK ? NC_SUCCESS : E_OPERATION_FAILED;
+	return ncCryptoSha256HkdfExtract(saltSpan, ikmSpan, ck->value) == CSTATUS_OK 
+		? NC_SUCCESS 
+		: E_OPERATION_FAILED;
 }
 
 
@@ -286,7 +288,7 @@ static _nc_fn_inline cstatus_t _getMessageKey(
 	ncSpanInit(&okmSpan, messageKey->value, sizeof(struct message_key));				/* Output produces a message key (write it directly to struct memory) */
 	
 	/* Nonce is the info */
-	return ncCryptoSha256HkdfExpand(&prkSpan, &nonce, &okmSpan);
+	return ncCryptoSha256HkdfExpand(prkSpan, nonce, okmSpan);
 }
 
 static _nc_fn_inline NCResult _encryptNip44Ex(
@@ -380,7 +382,7 @@ static _nc_fn_inline cstatus_t _computeHmac(const uint8_t key[NC_HMAC_KEY_SIZE],
 
 	ncSpanInitC(&keySpan, key, NC_HMAC_KEY_SIZE);
 
-	return ncCryptoHmacSha256(&keySpan, &payload, hmacOut);
+	return ncCryptoHmacSha256(keySpan, payload, hmacOut);
 }
 
 static NCResult _verifyMacEx(
@@ -650,7 +652,7 @@ NC_EXPORT NCResult NC_CC NCSignData(
 	ncSpanInitC(&dataSpan, data, dataSize);
 
 	/* Compute sha256 of the data before signing */
-	if(ncCryptoDigestSha256(&dataSpan, digest) != CSTATUS_OK)
+	if(ncCryptoDigestSha256(dataSpan, digest) != CSTATUS_OK)
 	{
 		return E_INVALID_ARG;
 	}
@@ -708,7 +710,7 @@ NC_EXPORT NCResult NC_CC NCVerifyData(
 	ncSpanInitC(&dataSpan, data, dataSize);
 
 	/* Compute sha256 of the data before verifying */
-	if (ncCryptoDigestSha256(&dataSpan, digest) != CSTATUS_OK)
+	if (ncCryptoDigestSha256(dataSpan, digest) != CSTATUS_OK)
 	{
 		return E_INVALID_ARG;
 	}
diff --git a/src/noscryptutil.c b/src/noscryptutil.c
index 97526d9..56acb1b 100644
--- a/src/noscryptutil.c
+++ b/src/noscryptutil.c
@@ -34,6 +34,23 @@
 	#error "Utilities library must be disabled when using extreme compat mode"
 #endif /* NC_EXTREME_COMPAT */
 
+#define MIN_PADDING_SIZE		0x20u
+#define NIP44_VERSION_SIZE		0x01u
+#define NIP44_PT_LEN_SIZE		sizeof(uint16_t)
+
+/*
+* minimum size for a valid nip44 payload
+* 1 byte version + 32 byte nonce + 32 byte mac + 2 byte ptSize + 32bytes minimum length
+*/
+#define NIP44_MIN_PAYLOAD_SIZE  (NIP44_VERSION_SIZE + 0x20 + 0x02 + 0x20 + 0x02)
+
+/*
+* The minimum ciphertext size is the minimum padded size + the minimum
+* size of the plaintext length field
+*/
+#define NIP44_MIN_CIPHERTEXT_SIZE (MIN_PADDING_SIZE + NIP44_PT_LEN_SIZE)
+
+
 #define _nc_mem_free(x) if(x != NULL) { free(x); x = NULL; }
 #define _nc_mem_alloc(elements, size) calloc(elements, size);
 #define ZERO_FILL ncCryptoSecureZero
@@ -51,7 +68,6 @@
 	#define CHECK_ARG_IS(is, expected, argPos)
 #endif /* !NC_DISABLE_INPUT_VALIDATION */
 
-
 #ifdef _NC_IS_WINDOWS
 	
 	#include <math.h>
@@ -73,38 +89,24 @@
 	}
 #endif
 
-#define MIN_PADDING_SIZE		0x20u
-#define NIP44_VERSION_SIZE		0x01u
-#define NIP44_PT_LEN_SIZE		sizeof(uint16_t)
-
-/*
-* minimum size for a valid nip44 payload
-* 1 byte version + 32 byte nonce + 32 byte mac + 2 byte ptSize + 32bytes minimum length
-*/
-#define NIP44_MIN_PAYLOAD_SIZE  (NIP44_VERSION_SIZE + 0x20 + 0x02 + 0x20 + 0x02)
-
-/*
-* The minimum ciphertext size is the minimum padded size + the minimum
-* size of the plaintext length field
-*/
-#define NIP44_MIN_CIPHERTEXT_SIZE (MIN_PADDING_SIZE + NIP44_PT_LEN_SIZE)
-
-
 /* Currently were on nip44 version 2 */
 static const uint8_t Nip44VersionValue[1] = { 0x02u };
 
-struct nc_util_enc_struct {
+struct cipher_buffer_state {
+	
+	cspan_t input;
+	span_t output;
 
-	uint32_t _flags;
+	cspan_t actualOutput;
+};
 
-	cspan_t cipherInput;
+struct nc_util_enc_struct {
 
-	/* 
-		The data this span points to is allocated during initialization 
-	*/
-	span_t cipherOutput;
+	uint32_t _flags;
 
 	NCEncryptionArgs encArgs;
+
+	struct cipher_buffer_state buffer;
 };
 
 static _nc_fn_inline span_t _ncUtilAllocSpan(uint32_t count, size_t size)
@@ -126,6 +128,11 @@ static _nc_fn_inline span_t _ncUtilAllocSpan(uint32_t count, size_t size)
 	return span;
 }
 
+static _nc_fn_inline void _ncUtilZeroSpan(span_t span)
+{
+	ZERO_FILL(span.data, span.size);
+}
+
 static _nc_fn_inline void _ncUtilFreeSpan(span_t span)
 {
 	_nc_mem_free(span.data);
@@ -198,7 +205,7 @@ static _nc_fn_inline uint32_t _calcNip44TotalOutSize(uint32_t inputSize)
 	return bufferSize;
 }
 
-static _nc_fn_inline cspan_t _nip44GetMacData(cspan_t payload)
+static _nc_fn_inline span_t _nip44GetMacData(span_t payload)
 {
 	DEBUG_ASSERT(payload.size > NIP44_VERSION_SIZE + NC_ENCRYPTION_MAC_SIZE);
 
@@ -216,7 +223,7 @@ static _nc_fn_inline cspan_t _nip44GetMacData(cspan_t payload)
 	* macData = ct.size - version.size + mac.size
 	*/
 
-	return ncSpanSliceC(
+	return ncSpanSlice(
 		payload,
 		NIP44_VERSION_SIZE,
 		payload.size - (NIP44_VERSION_SIZE + NC_ENCRYPTION_MAC_SIZE)
@@ -237,70 +244,105 @@ static _nc_fn_inline span_t _nip44GetMacOutput(span_t payload)
 	);
 }
 
-static _nc_fn_inline cspan_t _nip44ParseMac(cspan_t payload)
+static _nc_fn_inline int _nip44ParseSegments(
+	cspan_t payload, 
+	cspan_t* nonce,
+	cspan_t* mac,
+	cspan_t* macData,
+	cspan_t* cipherText
+)
 {
-	DEBUG_ASSERT(payload.size >= NIP44_MIN_PAYLOAD_SIZE);
+	if (payload.size < NIP44_MIN_PAYLOAD_SIZE)
+	{
+		return 0;
+	}
+
+	/* slice after the version and before the mac segments */
+	*nonce = ncSpanSliceC(
+		payload,
+		NIP44_VERSION_SIZE,
+		NC_ENCRYPTION_NONCE_SIZE
+	);
 
 	/*
 	* Mac is the final 32 bytes of the ciphertext buffer
 	*/
-	return ncSpanSliceC(
+	*mac = ncSpanSliceC(
 		payload,
 		payload.size - NC_ENCRYPTION_MAC_SIZE,
 		NC_ENCRYPTION_MAC_SIZE
 	);
-}
 
-static _nc_fn_inline cspan_t _nip44ParseCipherText(cspan_t payload)
-{
-	DEBUG_ASSERT(payload.size >= NIP44_MIN_PAYLOAD_SIZE);
+	/*
+	* The mac data is the nonce+ct segment of the buffer for mac computation.
+	*/
+	*macData = ncSpanSliceC(
+		payload,
+		NIP44_VERSION_SIZE,
+		payload.size - (NIP44_VERSION_SIZE + NC_ENCRYPTION_MAC_SIZE)
+	);
 
-	/* ct is all of the data after the nonce and before the mac segment */
-	return ncSpanSliceC(
+	/*
+	* Ciphertext is after the nonce segment and before the mac segment
+	*/
+	*cipherText = ncSpanSliceC(
 		payload,
 		NIP44_VERSION_SIZE + NC_ENCRYPTION_NONCE_SIZE,
 		payload.size - (NIP44_VERSION_SIZE + NC_ENCRYPTION_NONCE_SIZE + NC_ENCRYPTION_MAC_SIZE)
 	);
+
+	return 1;
 }
 
-static _nc_fn_inline cspan_t _nip44ParseNonce(cspan_t payload)
+
+static _nc_fn_inline void _cipherPublishOutput(NCUtilCipherContext* buffer, uint32_t offset, uint32_t size)
 {
-	DEBUG_ASSERT(payload.size >= NIP44_MIN_PAYLOAD_SIZE);
+	span_t slice;
 
-	/* slice after the version and before the mac segments */
-	return ncSpanSliceC(
-		payload,
-		NIP44_VERSION_SIZE,
-		NC_ENCRYPTION_NONCE_SIZE
-	);
+	DEBUG_ASSERT(ncSpanIsValid(buffer->buffer.output));
+
+	if (size == 0)
+	{
+		ncSpanInitC(&buffer->buffer.actualOutput, NULL, 0);
+	}
+	else
+	{
+		/* use slice for debug guards */
+		slice = ncSpanSlice(buffer->buffer.output, offset, size);
+		ncSpanInitC(&buffer->buffer.actualOutput, slice.data, slice.size);
+	}	
 }
 
+/*
+* I want the encryption/decyption functions to be indempodent
+* meaning all mutations that happen can be repeated without
+* side effects. IE no perminent state changes that can't be
+* undone.
+*/
+
 static NCResult _nip44EncryptCompleteCore(
 	const NCContext* libContext,
 	const NCSecretKey* sk,
 	const NCPublicKey* pk,
-	NCEncryptionArgs encArgs,
-	cspan_t plainText,
-	span_t payload
+	NCUtilCipherContext* state
 )
 {
 
 	NCResult result;
-	cspan_t macData, cPayload;
-	span_t macOutput;
-	uint32_t outPos, paddedCtSize;
+	cspan_t plainText;
+	span_t macData, macOutput, payload;
+	uint32_t outPos;
 	uint8_t ptSize[NIP44_PT_LEN_SIZE];
 	uint8_t hmacKeyOut[NC_ENCRYPTION_MAC_SIZE];
+	NCEncryptionArgs encArgs;
 
 	outPos = 0;
+	encArgs = state->encArgs;
+	payload = state->buffer.output;
+	plainText = state->buffer.input;
 
 	DEBUG_ASSERT(encArgs.version == NC_ENC_VERSION_NIP44);
 
-	ncSpanInitC(&cPayload, payload.data, payload.size);
-
-	/* Padded size is required to know how large the CT buffer is for encryption */
-	paddedCtSize = _calcNip44PtPadding(plainText.size);
-
 	/* Start by appending the version number */
 	ncSpanAppend(payload, &outPos, Nip44VersionValue, sizeof(Nip44VersionValue));
 
@@ -343,9 +385,9 @@ static NCResult _nip44EncryptCompleteCore(
 
 	result = NCSetEncryptionData(
 		&encArgs,
-		(payload.data + outPos),			/* in place encryption */
-		(payload.data + outPos),
-		paddedCtSize + NIP44_PT_LEN_SIZE	/* Plaintext + pt size must be encrypted */
+		ncSpanGetOffset(payload, outPos),	/* in place encryption */
+		ncSpanGetOffset(payload, outPos),
+		NIP44_PT_LEN_SIZE + _calcNip44PtPadding(plainText.size) 	/* Plaintext + pt size must be encrypted */
 	);
 
 	DEBUG_ASSERT(result == NC_SUCCESS);
@@ -363,7 +405,7 @@ static NCResult _nip44EncryptCompleteCore(
 	* the plaintext data, followed by zero padding.
 	*/
 
-	ncSpanWrite(payload, outPos, ptSize, NIP44_PT_LEN_SIZE);
+	ncSpanWrite(payload, outPos, ptSize, sizeof(ptSize));
 
 	ncSpanWrite(
 		payload,
@@ -387,15 +429,15 @@ static NCResult _nip44EncryptCompleteCore(
 		this helper captures that data segment into a span
 	*/
 
-	macData = _nip44GetMacData(cPayload);
+	macData = _nip44GetMacData(payload);
 	macOutput = _nip44GetMacOutput(payload);
 
 	result = NCComputeMac(
 		libContext,
 		hmacKeyOut,
-		macData.data,
+		ncSpanGetOffset(macData, 0),
 		macData.size,
-		macOutput.data
+		ncSpanGetOffset(macOutput, 0)
 	);
 
 	if (result != NC_SUCCESS)
@@ -407,6 +449,9 @@ static NCResult _nip44EncryptCompleteCore(
 
 	DEBUG_ASSERT2(outPos == payload.size, "Buffer under/overflow detected");
 
+	/* publish all payload bytes to output */
+	_cipherPublishOutput(state, 0, outPos);
+
 	/* zero hmac key before returning */
 	ZERO_FILL(hmacKeyOut, sizeof(hmacKeyOut));
 
@@ -418,45 +463,55 @@ static NCResult _nip44DecryptCompleteCore(
 	const NCContext* libContext,
 	const NCSecretKey* recvKey,
 	const NCPublicKey* sendKey,
-	const NCUtilCipherContext* cipher
+	NCUtilCipherContext* state
 )
 {
 	NCResult result;
 	NCMacVerifyArgs macArgs;
 	NCEncryptionArgs encArgs;
-	cspan_t macData, macValue, cipherText, nonce;
+	cspan_t macData, macValue, nonce, payload, cipherText;
+	span_t output;
+	uint16_t ptSize;
 
-	DEBUG_ASSERT(libContext && recvKey && sendKey && cipher);
-	DEBUG_ASSERT(cipher->encArgs.version == NC_ENC_VERSION_NIP44);
+	DEBUG_ASSERT(libContext && recvKey && sendKey && state);
+	DEBUG_ASSERT(state->encArgs.version == NC_ENC_VERSION_NIP44);
+	DEBUG_ASSERT(state->buffer.input.size >= NIP44_MIN_PAYLOAD_SIZE);
 
 	/* ensure decryption mode */
-	DEBUG_ASSERT(cipher->_flags & NC_UTIL_CIPHER_MODE_DECRYPT);
+	DEBUG_ASSERT(state->_flags & NC_UTIL_CIPHER_MODE_DECRYPT);
 
 	/* store local stack copy for safe mutation */
-	encArgs = cipher->encArgs;
+	encArgs = state->encArgs;
+	payload = state->buffer.input;
+	output = state->buffer.output;
 
-	nonce = _nip44ParseNonce(cipher->cipherInput);
+	/*
+	* Copy the input buffer to the output buffer because the 
+	* decryption happens in-place and needs a writable buffer
+	* 
+	* After the operation is complete, we will assign the actual plaintext 
+	* data to the actual output buffer
+	*/
 
-	/* Verify mac if the user allowed it */
-	if ((cipher->_flags & NC_UTIL_CIPHER_MAC_NO_VERIFY) == 0)
-	{
-		/*
-		* The mac data to verify against is the nonce+ciphertext data
-		* from within the nip44 message payload
-		*/
+	DEBUG_ASSERT2(ncSpanIsValid(output), "Output buffer was not allocated");
 
-		macData = _nip44GetMacData(cipher->cipherInput);
-		macValue = _nip44ParseMac(cipher->cipherInput);
+	if (!_nip44ParseSegments(payload, &nonce, &macValue, &macData, &cipherText))
+	{
+		return E_CIPHER_INVALID_FORMAT;
+	}
 
+	/* Verify mac if the user allowed it */
+	if ((state->_flags & NC_UTIL_CIPHER_MAC_NO_VERIFY) == 0)
+	{
 		DEBUG_ASSERT(macValue.size == NC_ENCRYPTION_MAC_SIZE);
-		DEBUG_ASSERT(macData.size > NC_ENCRYPTION_NONCE_SIZE + 0x20);
+		DEBUG_ASSERT(macData.size > NC_ENCRYPTION_NONCE_SIZE + MIN_PADDING_SIZE);
 
 		/* Assign the mac data to the mac verify args */
-		macArgs.mac32 = macValue.data;
-		macArgs.nonce32 = nonce.data;
+		macArgs.mac32 = ncSpanGetOffsetC(macValue, 0);
+		macArgs.nonce32 = ncSpanGetOffsetC(nonce, 0);
 		
 		/* payload for verifying a mac in nip44 is the nonce+ciphertext */
-		macArgs.payload = macData.data;
+		macArgs.payload = ncSpanGetOffsetC(macData, 0);
 		macArgs.payloadSize = macData.size;
 
 		/* Verify the mac */
@@ -474,44 +529,60 @@ static NCResult _nip44DecryptCompleteCore(
 		}
 	}
 
-	cipherText = _nip44ParseCipherText(cipher->cipherInput);
-	
-	DEBUG_ASSERT2(cipherText.size >= MIN_PADDING_SIZE, "Cipertext segment was parsed incorrectly. Too small");
-
-	/* manually sign nonce */
-	encArgs.nonceData = nonce.data;
-
-	/*
-	* Remember the decryption operation is symmetric, it reads the input bytes and writes 
-	* directly to the output. 
-	* 
-	* The decryption is performed on the ciphertext segment and we can write the output 
-	* directly the output buffer.
-	* 
-	* The leading 2 bytes will be the encoded plaintext size, followed by the plaintext data
-	* and padding. That's okay. The user will call NCUtilCipherGetOutputSize to get the
-	* actual size of the plaintext, which will exlcude the leading 2 bytes and padding.
+	/* 
+	* manually assign nonce because it's a constant pointer which
+	* is not allowed when calling setproperty 
 	*/
+	encArgs.nonceData = ncSpanGetOffsetC(nonce, 0);
 
-	DEBUG_ASSERT(cipher->cipherOutput.size >= cipherText.size);
-
+	DEBUG_ASSERT2(cipherText.size >= MIN_PADDING_SIZE, "Cipertext segment was parsed incorrectly. Too small");
+	
 	result = NCSetEncryptionData(
 		&encArgs,
-		cipherText.data,
-		cipher->cipherOutput.data,
+		ncSpanGetOffsetC(cipherText, 0),
+		ncSpanGetOffset(output, 0),			/*decrypt ciphertext and write directly to the output buffer */
 		cipherText.size
 	);
 
+	DEBUG_ASSERT(result == NC_SUCCESS);
+
+	/*
+	* If decryption was successful, the data should be written 
+	* directly to the output buffer
+	*/
+	result = NCDecrypt(libContext, recvKey, sendKey, &encArgs);
+
 	if (result != NC_SUCCESS)
 	{
 		return result;
 	}
 
 	/*
-	* If decryption was successful, the data should be written 
-	* directly to the output buffer
+	* Parse CT length and assign the output buffer.
+	* 
+	* PT size is stored at the beginning of the ciphertext
+	* segment and is 2 bytes in size, big endian.
 	*/
-	result = NCDecrypt(libContext, recvKey, sendKey, &encArgs);
+
+	ptSize = (uint16_t)(output.data[0] << 8 | output.data[1]);
+
+	/*
+	* If the PT is corrupted or set maliciously, it can overrun
+	* the current buffer. The PT size must be less than the
+	* ciphertext size.
+	*/
+	if (!ncSpanIsValidRange(output, NIP44_PT_LEN_SIZE, ptSize))
+	{
+		return E_OPERATION_FAILED;
+	}
+
+	/*
+	* actual output span should now point to the decrypted plaintext
+	* data segment
+	*/
+	_cipherPublishOutput(state, NIP44_PT_LEN_SIZE, ptSize);
+
+	DEBUG_ASSERT(state->buffer.actualOutput.size < cipherText.size);
 
 	return result;
 }
@@ -582,13 +653,13 @@ NC_EXPORT void NC_CC NCUtilCipherFree(NCUtilCipherContext* encCtx)
 	* If zero on free flag is set, we can zero all output memory 
 	* before returning the buffer back to the heap
 	*/
-	if ((encCtx->_flags & NC_UTIL_CIPHER_ZERO_ON_FREE) > 0 && encCtx->cipherOutput.data) 
+	if ((encCtx->_flags & NC_UTIL_CIPHER_ZERO_ON_FREE) > 0 && ncSpanIsValid(encCtx->buffer.output)) 
 	{
-		ZERO_FILL(encCtx->cipherOutput.data, encCtx->cipherOutput.size);
+		_ncUtilZeroSpan(encCtx->buffer.output);
 	}
 
-	/* Free output buffers */
-	_ncUtilFreeSpan(encCtx->cipherOutput);
+	/* Free output buffers (null buffers are allowed) */
+	_ncUtilFreeSpan(encCtx->buffer.output);
 
 	/* context can be released */
 	_nc_mem_free(encCtx);
@@ -604,14 +675,12 @@ NC_EXPORT NCResult NC_CC NCUtilCipherInit(
 
 	CHECK_NULL_ARG(encCtx, 0);
 	CHECK_NULL_ARG(inputData, 1);
-	/* The output state must not have alraedy been allocated */
-	CHECK_ARG_IS(encCtx->cipherOutput.data == NULL, 0);
 
 	if ((encCtx->_flags & NC_UTIL_CIPHER_MODE_DECRYPT) > 0)
 	{
 		/*
 		* Validate the input data for proper format for 
-		* the current cipher version
+		* the current state version
 		*/
 		switch (encCtx->encArgs.version)
 		{
@@ -652,7 +721,7 @@ NC_EXPORT NCResult NC_CC NCUtilCipherInit(
 	{
 		/*
 		* Calculate the correct output size to store the encryption
-		* data for the given cipher version
+		* data for the given state version
 		*/
 		outputSize = NCUtilGetEncryptionBufferSize(encCtx->encArgs.version, inputSize);
 	}
@@ -662,15 +731,48 @@ NC_EXPORT NCResult NC_CC NCUtilCipherInit(
 		return outputSize;
 	}
 
+	/*
+	* If the buffer was previously allocated, the reuseable flag
+	* must be set to allow the buffer to be re-used for another
+	* operation.
+	*/
+
+	if (ncSpanIsValid(encCtx->buffer.output))
+	{
+		CHECK_ARG_IS((encCtx->_flags & NC_UTIL_CIPHER_REUSEABLE) > 0, 0);
+
+		/*
+		* if the existing buffer is large enough to hold the new 
+		* data reuse it, otherwise free it and allocate a new buffer
+		*/
+
+		if (outputSize <= encCtx->buffer.output.size)
+		{
+			_ncUtilZeroSpan(encCtx->buffer.output);
+
+			goto AssignInputAndExit;
+		}
+		else
+		{
+			_ncUtilFreeSpan(encCtx->buffer.output);
+		}
+	}
+
 	/* Alloc output buffer within the struct */
-	encCtx->cipherOutput = _ncUtilAllocSpan((uint32_t)outputSize, sizeof(uint8_t));
+	encCtx->buffer.output = _ncUtilAllocSpan((uint32_t)outputSize, sizeof(uint8_t));
 
-	if (!encCtx->cipherOutput.data)
+	if (!ncSpanIsValid(encCtx->buffer.output))
 	{
 		return E_OUT_OF_MEMORY;
 	}
 
-	ncSpanInitC(&encCtx->cipherInput, inputData, inputSize);
+AssignInputAndExit:
+
+	/* Confirm output was allocated */
+	DEBUG_ASSERT(ncSpanIsValid(encCtx->buffer.output));
+
+	/* Assign the input data span to point to the assigned input data */
+	ncSpanInitC(&encCtx->buffer.input, inputData, inputSize);
 
 	return NC_SUCCESS;
 }
@@ -684,48 +786,14 @@ NC_EXPORT NCResult NC_CC NCUtilCipherGetFlags(const NCUtilCipherContext* ctx)
 
 NC_EXPORT NCResult NC_CC NCUtilCipherGetOutputSize(const NCUtilCipherContext* encCtx)
 {
-	uint16_t nip44PtSize;
-
 	CHECK_NULL_ARG(encCtx, 0);
 
-	/*
-	* if nip44 decryption is desired, the output buffer will be 
-	* overallocated. It will also contain some padding bytes
-	* so we need to parse the plaintext size from the buffer
-	* and return that as the output size.
-	*/
-	if (encCtx->encArgs.version == NC_ENC_VERSION_NIP44 
-		&& (encCtx->_flags & NC_UTIL_CIPHER_MODE_DECRYPT) > 0)
+	if (!ncSpanIsValidC(encCtx->buffer.actualOutput))
 	{
-
-		/* ensure the output has been allocated correctly */
-		if (encCtx->cipherOutput.size < NIP44_PT_LEN_SIZE)
-		{
-			return E_INVALID_CONTEXT;
-		}
-
-		/*
-		* If a decryption operation was performed the leading 2 bytes will
-		* be the big-endian encoded plaintext size. This function should 
-		* return the size of the plaintext data, not the entire buffer.
-		*/
-
-		nip44PtSize = (encCtx->cipherOutput.data[0] << 8) | encCtx->cipherOutput.data[1];
-
-		/*
-		* If improperly decryption/formatted, the pt size may be some really large 
-		* number when decoded, so make sure it doesn't point to a location outside
-		* the buffer, that would be invalid
-		*/
-		if (nip44PtSize > (encCtx->cipherOutput.size - NIP44_PT_LEN_SIZE))
-		{
-			return E_CIPHER_INVALID_FORMAT;
-		}
-
-		return (NCResult)nip44PtSize;
+		return E_CIPHER_NO_OUTPUT;
 	}
 
-	return (NCResult)(encCtx->cipherOutput.size);
+	return (NCResult)(encCtx->buffer.actualOutput.size);
 }
 
 NC_EXPORT NCResult NC_CC NCUtilCipherReadOutput(
@@ -734,55 +802,24 @@ NC_EXPORT NCResult NC_CC NCUtilCipherReadOutput(
 	uint32_t outputSize
 )
 {
-	NCResult result;
-
-	CHECK_NULL_ARG(encCtx, 0)
-	CHECK_NULL_ARG(output, 1)
-
-	/*
-	* Again if in nip44 decrypt mode we only want the 
-	* actual plaintext data
-	*/
+	CHECK_NULL_ARG(encCtx, 0);
+	CHECK_NULL_ARG(output, 1);
 
-	if (encCtx->encArgs.version == NC_ENC_VERSION_NIP44
-		&& (encCtx->_flags & NC_UTIL_CIPHER_MODE_DECRYPT) > 0)
+	if (!ncSpanIsValidC(encCtx->buffer.actualOutput))
 	{
-		result = NCUtilCipherGetOutputSize(encCtx);
-		
-		if (result < 0) 
-		{
-			return result;
-		}
-
-		DEBUG_ASSERT((result + NIP44_PT_LEN_SIZE) < encCtx->cipherOutput.size);
-
-		/* Make sure the output buffer is large enough */
-		CHECK_ARG_RANGE(outputSize, result, UINT32_MAX, 2);
-
-		/*
-		* Plaintext data sits directly after the length bytes 
-		* and up to the length of the plaintext size
-		*/
-		MEMMOV(
-			output,
-			encCtx->cipherOutput.data + NIP44_PT_LEN_SIZE,
-			(uint32_t)result
-		);
-
-		return result;
+		return E_CIPHER_NO_OUTPUT;
 	}
-	else
-	{
-		CHECK_ARG_RANGE(outputSize, encCtx->cipherOutput.size, UINT32_MAX, 2);
 
-		MEMMOV(
-			output,
-			encCtx->cipherOutput.data,
-			encCtx->cipherOutput.size
-		);
+	/* Buffer must be as large as the output data  */
+	CHECK_ARG_RANGE(outputSize, encCtx->buffer.actualOutput.size, UINT32_MAX, 2);
 
-		return (NCResult)encCtx->cipherOutput.size;
-	}
+	ncSpanReadC(
+		encCtx->buffer.actualOutput,
+		output,
+		outputSize
+	);
+
+	return (NCResult)encCtx->buffer.actualOutput.size;
 }
 
 NC_EXPORT NCResult NCUtilCipherSetProperty(
@@ -804,7 +841,7 @@ NC_EXPORT NCResult NCUtilCipherSetProperty(
 }
 
 NC_EXPORT NCResult NC_CC NCUtilCipherUpdate(
-	const NCUtilCipherContext* encCtx,
+	NCUtilCipherContext* encCtx,
 	const NCContext* libContext,
 	const NCSecretKey* sk,
 	const NCPublicKey* pk
@@ -816,15 +853,18 @@ NC_EXPORT NCResult NC_CC NCUtilCipherUpdate(
 	CHECK_NULL_ARG(pk, 3);
 
 	/* Make sure input & output buffers have been assigned/allocated */
-	if (encCtx->cipherOutput.data == NULL)
+	if (!ncSpanIsValid(encCtx->buffer.output))
 	{
 		return E_INVALID_CONTEXT;
 	}
-	if (encCtx->cipherInput.data == NULL)
+	if (!ncSpanIsValidC(encCtx->buffer.input))
 	{
 		return E_INVALID_CONTEXT;
 	}
 
+	/* Reset output data pointer incase it has been moved */
+	_cipherPublishOutput(encCtx, 0, 0);
+
 	switch (encCtx->encArgs.version)
 	{
 	case NC_ENC_VERSION_NIP44:
@@ -841,14 +881,7 @@ NC_EXPORT NCResult NC_CC NCUtilCipherUpdate(
 				return E_CIPHER_BAD_NONCE;
 			}
 
-			return _nip44EncryptCompleteCore(
-				libContext,
-				sk,
-				pk,
-				encCtx->encArgs,
-				encCtx->cipherInput,
-				encCtx->cipherOutput
-			);
+			return _nip44EncryptCompleteCore(libContext, sk, pk, encCtx);
 		}
 
 	default:
diff --git a/src/providers/bcrypt.c b/src/providers/bcrypt.c
index d1b9aa5..67ae695 100644
--- a/src/providers/bcrypt.c
+++ b/src/providers/bcrypt.c
@@ -63,7 +63,7 @@ _IMPLSTB NTSTATUS _bcInitSha256(struct _bcrypt_ctx* ctx, DWORD flags)
 	return result;
 }
 
-_IMPLSTB NTSTATUS _bcCreateHmac(struct _bcrypt_ctx* ctx, const cspan_t* key)
+_IMPLSTB NTSTATUS _bcCreateHmac(struct _bcrypt_ctx* ctx, cspan_t key)
 {
 	/*
 	 * NOTE: 
@@ -79,8 +79,8 @@ _IMPLSTB NTSTATUS _bcCreateHmac(struct _bcrypt_ctx* ctx, const cspan_t* key)
 		&ctx->hHash, 
 		NULL, 
 		0, 
-		(uint8_t*)key->data, 
-		key->size, 
+		(uint8_t*)key.data, 
+		key.size, 
 		BCRYPT_HASH_REUSABLE_FLAG	/* Enable reusable for expand function */
 	);
 }
@@ -92,7 +92,7 @@ _IMPLSTB NTSTATUS _bcCreate(struct _bcrypt_ctx* ctx)
 	/* Zero out key span for 0 size and NULL data ptr */
 	SecureZeroMemory(&key, sizeof(cspan_t));
 
-	return _bcCreateHmac(ctx, &key);
+	return _bcCreateHmac(ctx, key);
 }
 
 _IMPLSTB NTSTATUS _bcHashDataRaw(const struct _bcrypt_ctx* ctx, const uint8_t* data, uint32_t len)
@@ -100,9 +100,9 @@ _IMPLSTB NTSTATUS _bcHashDataRaw(const struct _bcrypt_ctx* ctx, const uint8_t* d
 	return BCryptHashData(ctx->hHash, (uint8_t*)data, len, 0);
 }
 
-_IMPLSTB NTSTATUS _bcHashData(const struct _bcrypt_ctx* ctx, const cspan_t* data)
+_IMPLSTB NTSTATUS _bcHashData(const struct _bcrypt_ctx* ctx, cspan_t data)
 {
-	return _bcHashDataRaw(ctx, data->data, data->size);
+	return _bcHashDataRaw(ctx, data.data, data.size);
 }
 
 _IMPLSTB NTSTATUS _bcFinishHash(const struct _bcrypt_ctx* ctx, sha256_t digestOut32)
@@ -146,7 +146,7 @@ _IMPLSTB void _bcDestroyCtx(struct _bcrypt_ctx* ctx)
 	/* Export function fallack */
 	#define _IMPL_CRYPTO_SHA256_DIGEST			_bcrypt_sha256_digest	
 
-	_IMPLSTB cstatus_t _bcrypt_sha256_digest(const cspan_t* data, sha256_t digestOut32)
+	_IMPLSTB cstatus_t _bcrypt_sha256_digest(cspan_t data, sha256_t digestOut32)
 	{
 		cstatus_t result;
 		struct _bcrypt_ctx ctx;
@@ -177,7 +177,7 @@ _IMPLSTB void _bcDestroyCtx(struct _bcrypt_ctx* ctx)
 	/* Export function */
 	#define _IMPL_CRYPTO_SHA256_HMAC				_bcrypt_hmac_sha256	
 	
-	_IMPLSTB cstatus_t _bcrypt_hmac_sha256(const cspan_t* key, const cspan_t* data, sha256_t hmacOut32)
+	_IMPLSTB cstatus_t _bcrypt_hmac_sha256(cspan_t key, cspan_t data, sha256_t hmacOut32)
 	{
 		cstatus_t result;
 		struct _bcrypt_ctx ctx;
@@ -213,7 +213,7 @@ _IMPLSTB void _bcDestroyCtx(struct _bcrypt_ctx* ctx)
 
 	#define _IMPL_CRYPTO_SHA256_HKDF_EXPAND		_bcrypt_fallback_hkdf_expand
 
-	cstatus_t _bcrypt_hkdf_update(void* ctx, const cspan_t* data)
+	cstatus_t _bcrypt_hkdf_update(void* ctx, cspan_t data)
 	{
 		DEBUG_ASSERT(ctx != NULL)
 
@@ -229,7 +229,7 @@ _IMPLSTB void _bcDestroyCtx(struct _bcrypt_ctx* ctx)
 		return CSTATUS_OK;
 	}
 
-	_IMPLSTB cstatus_t _bcrypt_fallback_hkdf_expand(const cspan_t* prk, const cspan_t* info, span_t* okm)
+	_IMPLSTB cstatus_t _bcrypt_fallback_hkdf_expand(cspan_t prk, cspan_t info, span_t okm)
 	{
 		cstatus_t result;
 		struct _bcrypt_ctx ctx;
diff --git a/src/providers/mbedtls.c b/src/providers/mbedtls.c
index df5201f..8479380 100644
--- a/src/providers/mbedtls.c
+++ b/src/providers/mbedtls.c
@@ -95,13 +95,13 @@ _IMPLSTB const mbedtls_md_info_t* _mbed_sha256_alg(void)
 	
 	#define _IMPL_CRYPTO_SHA256_DIGEST			_mbed_sha256_digest	
 
-	_IMPLSTB cstatus_t _mbed_sha256_digest(const cspan_t* data, sha256_t digestOut32)
+	_IMPLSTB cstatus_t _mbed_sha256_digest(cspan_t data, sha256_t digestOut32)
 	{
-		_overflow_check(data->size)
+		_overflow_check(data.size)
 
 		return mbedtls_sha256(
-			data->data, 
-			data->size, 
+			data.data, 
+			data.size, 
 			digestOut32, 
 			0				/* Set 0 for sha256 mode */
 		) == 0 ? CSTATUS_OK : CSTATUS_FAIL;
@@ -114,19 +114,19 @@ _IMPLSTB const mbedtls_md_info_t* _mbed_sha256_alg(void)
 
 	#define _IMPL_CRYPTO_SHA256_HMAC			_mbed_sha256_hmac
 
-	_IMPLSTB cstatus_t _mbed_sha256_hmac(const cspan_t* key, const cspan_t* data, sha256_t hmacOut32)
+	_IMPLSTB cstatus_t _mbed_sha256_hmac(cspan_t key, cspan_t data, sha256_t hmacOut32)
 	{
-		_overflow_check(data->size)
+		_overflow_check(data.size)
 
 		/* Keys should never be large enough for this to matter, but sanity check. */
-		DEBUG_ASSERT2(key->size < SIZE_MAX, "Expected key size to be less than SIZE_MAX")
+		DEBUG_ASSERT2(key.size < SIZE_MAX, "Expected key size to be less than SIZE_MAX")
 
 		return mbedtls_md_hmac(
 			_mbed_sha256_alg(),
-			key->data, 
-			key->size,
-			data->data, 
-			data->size,
+			key.data, 
+			key.size,
+			data.data, 
+			data.size,
 			hmacOut32
 		) == 0 ? CSTATUS_OK : CSTATUS_FAIL;
 	}
@@ -137,21 +137,21 @@ _IMPLSTB const mbedtls_md_info_t* _mbed_sha256_alg(void)
 
 	#define _IMPL_CRYPTO_SHA256_HKDF_EXPAND		_mbed_sha256_hkdf_expand
 
-	_IMPLSTB cstatus_t _mbed_sha256_hkdf_expand(const cspan_t* prk, const cspan_t* info, span_t* okm)
+	_IMPLSTB cstatus_t _mbed_sha256_hkdf_expand(cspan_t prk, cspan_t info, span_t okm)
 	{
 		/* These sizes should never be large enough to overflow on <64bit platforms, but sanity check */
-		DEBUG_ASSERT(okm->size < SIZE_MAX)
-		DEBUG_ASSERT(prk->size < SIZE_MAX)
-		DEBUG_ASSERT(info->size < SIZE_MAX)
+		DEBUG_ASSERT(okm.size < SIZE_MAX)
+		DEBUG_ASSERT(prk.size < SIZE_MAX)
+		DEBUG_ASSERT(info.size < SIZE_MAX)
 
 		return mbedtls_hkdf_expand(
 			_mbed_sha256_alg(),
-			prk->data, 
-			prk->size,
-			info->data, 
-			info->size,
-			okm->data, 
-			okm->size
+			prk.data, 
+			prk.size,
+			info.data, 
+			info.size,
+			okm.data, 
+			okm.size
 		) == 0 ? CSTATUS_OK : CSTATUS_FAIL;
 	}
 
diff --git a/tests/hex.h b/tests/hex.h
index e6a2a07..3cfe559 100644
--- a/tests/hex.h
+++ b/tests/hex.h
@@ -68,6 +68,7 @@ static span_t _fromHexString(const char* hexLiteral, uint32_t strLen)
 
 	if(!hexLiteral)
 	{
+		ncSpanInit(&hexBytes, NULL, 0);
 		return hexBytes;
 	}
 
@@ -125,13 +126,13 @@ static void PrintHexRaw(void* bytes, size_t len)
 */
 static void PrintHexBytes(span_t hexBytes)
 {
-	if (!hexBytes.data)
+	if (ncSpanIsValid(hexBytes))
 	{
-		puts("NULL");
+		PrintHexRaw(hexBytes.data, hexBytes.size);
 	}
 	else
 	{
-		PrintHexRaw(hexBytes.data, hexBytes.size);
+		puts("NULL");		
 	}
 }
 
diff --git a/tests/test.c b/tests/test.c
index 80b8704..b4cdef1 100644
--- a/tests/test.c
+++ b/tests/test.c
@@ -617,7 +617,7 @@ static int TestUtilNip44Encryption(
     span_t recvKey, 
     span_t nonce, 
     span_t expected,
-    const char* plainText
+    span_t plainText
 )
 {
     NCPublicKey recvPubKey;
@@ -634,7 +634,7 @@ static int TestUtilNip44Encryption(
     
     ENSURE(ctx != NULL);
 
-    TEST(NCUtilCipherInit(ctx, (const uint8_t*)plainText, strlen(plainText)), NC_SUCCESS);
+    TEST(NCUtilCipherInit(ctx, plainText.data, plainText.size), NC_SUCCESS);
 
     /* Nonce is required for nip44 encryption */
     TEST(NCUtilCipherSetProperty(ctx, NC_ENC_SET_NIP44_NONCE, nonce.data, nonce.size), NC_SUCCESS);
@@ -659,6 +659,8 @@ static int TestUtilNip44Encryption(
 
     /* Free encryption memory */
     NCUtilCipherFree(ctx);
+
+    return 0;
 }
 
 static int TestUtilNip44Decryption(
@@ -666,7 +668,7 @@ static int TestUtilNip44Decryption(
     span_t sendKey,
     span_t recvKey,
     span_t payload,
-    const char* expectedPt
+	span_t expectedPt
 )
 {
     NCPublicKey recvPubKey;
@@ -690,7 +692,7 @@ static int TestUtilNip44Decryption(
 
     NCResult plaintextSize = NCUtilCipherGetOutputSize(ctx);
 
-    TEST(plaintextSize, strlen(expectedPt));
+    TEST(plaintextSize, expectedPt.size);
 
     outData = (uint8_t*)malloc(plaintextSize);
 
@@ -700,12 +702,14 @@ static int TestUtilNip44Decryption(
     TEST(NCUtilCipherReadOutput(ctx, outData, plaintextSize), plaintextSize);
 
     /* Ensure encrypted payload matches */
-    TEST(memcmp(outData, expectedPt, plaintextSize), 0);
+    TEST(memcmp(outData, expectedPt.data, plaintextSize), 0);
 
     free(outData);
 
     /* Free encryption memory */
     NCUtilCipherFree(ctx);
+
+    return 0;
 }
 
 static int TestUtilFunctions(const NCContext* libCtx)
@@ -727,7 +731,7 @@ static int TestUtilFunctions(const NCContext* libCtx)
 		span_t recvKey = FromHexString("0000000000000000000000000000000000000000000000000000000000000002", sizeof(NCSecretKey));
 		span_t nonce = FromHexString("0000000000000000000000000000000000000000000000000000000000000001", NC_ENCRYPTION_NONCE_SIZE);
         span_t payload = FromHexString("02000000000000000000000000000000000000000000000000000000000000000179ed06e5548ad3ff58ca920e6c0b4329f6040230f7e6e5641f20741780f0adc35a09794259929a02bb06ad8e8cf709ee4ccc567e9d514cdf5781af27a3e905e55b1b", 99);
-        const char* plainText = "a";
+		span_t plainText = FromHexString("61", 1);
 
         if (TestUtilNip44Encryption(libCtx, sendKey, recvKey, nonce, payload, plainText) != 0) 
         {
@@ -740,9 +744,8 @@ static int TestUtilFunctions(const NCContext* libCtx)
         /* From the nip44 vectors file */
         span_t sendKey = FromHexString("0000000000000000000000000000000000000000000000000000000000000001", sizeof(NCSecretKey));
         span_t recvKey = FromHexString("0000000000000000000000000000000000000000000000000000000000000002", sizeof(NCSecretKey));
-        span_t nonce = FromHexString("0000000000000000000000000000000000000000000000000000000000000001", NC_ENCRYPTION_NONCE_SIZE);
         span_t payload = FromHexString("02000000000000000000000000000000000000000000000000000000000000000179ed06e5548ad3ff58ca920e6c0b4329f6040230f7e6e5641f20741780f0adc35a09794259929a02bb06ad8e8cf709ee4ccc567e9d514cdf5781af27a3e905e55b1b", 99);
-        const char* plainText = "a";
+		span_t plainText = FromHexString("61", 1);
 
         if (TestUtilNip44Decryption(libCtx, sendKey, recvKey, payload, plainText) != 0)
         {