Squashed commit of the following:

commit 942aed8a4e7c173a2c9423829c2b38087cbd49e4
Author: vnugent <public@vaughnnugent.com>
Date:   Tue Aug 6 20:54:03 2024 -0400

    chore: update changelog and mbedtls headers

commit 3b97f84fd0477eafcd6567eb8597b213e4136664
Author: vnugent <public@vaughnnugent.com>
Date:   Tue Aug 6 19:57:10 2024 -0400

    update libsecp256k1 to v0.5.1

commit 7989a2660997b909e0b99fc1dfb3bcfbb0528df3
Author: vnugent <public@vaughnnugent.com>
Date:   Tue Aug 6 19:42:25 2024 -0400

    update openssl to 3.3.1

commit e949ae5aa1fd25d4d11fe31e30b7d82ae7778dc2
Author: vnugent <public@vaughnnugent.com>
Date:   Mon Aug 5 18:01:03 2024 -0400

    fix: Find and fix openssl encryption bug

commit a60a3e1ca1d99d655c0cfc96e3952c371e8a8677
Author: vnugent <public@vaughnnugent.com>
Date:   Sun Aug 4 15:27:06 2024 -0400

    cleanup comments + return codes

commit 2aa7f4b6cdb2e0e8990e7177476f4104fd2e2b17
Author: vnugent <public@vaughnnugent.com>
Date:   Sat Jul 27 22:20:53 2024 -0400

    fix codeberg url

commit 1640f79776c6b291b49a39a6128c05888fc4153e
Author: vnugent <public@vaughnnugent.com>
Date:   Sat Jul 27 00:05:07 2024 -0400

    fix: Potential overflow in nip44 padding calculation

commit 07de078a3b5b7b0043d9f81bb5a9e750a3a0c7c1
Author: vnugent <public@vaughnnugent.com>
Date:   Fri Jul 26 23:37:15 2024 -0400

    refactor: Span invasion, checks and fix some evp api

commit 54f520e4bfc0fe23e2719d44b09739aa8709451c
Author: vnugent <public@vaughnnugent.com>
Date:   Tue Jul 23 19:55:13 2024 -0400

    latest changes

commit 12feb33dba2061415d6f39fa59dec16fafcda2a0
Author: vnugent <public@vaughnnugent.com>
Date:   Sun Jul 21 17:51:04 2024 -0400

    Push latest changes, patches, and internal upgrades

commit ffe42b6858f112a00405be4f0605ab1163063749
Author: vnugent <public@vaughnnugent.com>
Date:   Sat Jul 13 22:13:13 2024 -0400

    test: Add decryption test cases and fixes

commit 5dfafbc5a9214587533ec8b1dae2a962118d3650
Author: vnugent <public@vaughnnugent.com>
Date:   Fri Jul 12 22:14:00 2024 -0400

    feat: add decryption functionality to public api

commit 8df8c5aed4ac626171b451b5422c3b207e88000b
Author: vnugent <public@vaughnnugent.com>
Date:   Thu Jul 11 21:39:39 2024 -0400

    feat: Update sidecar utils library

commit 23fe6e8c8596333c2183f0f4389817087442c551
Author: vnugent <public@vaughnnugent.com>
Date:   Fri Jul 5 00:03:48 2024 -0400

    push latest utils and changes

commit dc71f861df8929deee300368b88ef47d45560695
Author: vnugent <public@vaughnnugent.com>
Date:   Mon Jul 1 15:05:34 2024 -0400

    fix: #7 fix confusing inline functions

commit 90166048046d2511f0bb74f8880180e82466d4c0
Author: vnugent <public@vaughnnugent.com>
Date:   Tue Jun 18 21:22:37 2024 -0400

    push pending changes

commit 461dd71069d0c0250752ac1256160605c33a6243
Author: vnugent <public@vaughnnugent.com>
Date:   Tue Jun 11 15:44:28 2024 -0400

    feat!: #4 Close #4. Add public nip04 support to api

commit a74f96251bcc81fb2c94fe75dd6f8043fd35fe0b
Merge: 1c26ef8 51d0aff
Author: vnugent <public@vaughnnugent.com>
Date:   Wed May 29 13:37:00 2024 -0400

    Merge branch 'master' into develop

commit 1c26ef86a04690120f4f752c7c5018a570ec5880
Author: vnugent <public@vaughnnugent.com>
Date:   Wed May 29 13:34:20 2024 -0400

    missed extra argument

commit 88c9095743a12cf8fc1793c607ba3a1e4fa86483
Author: vnugent <public@vaughnnugent.com>
Date:   Wed May 29 13:25:51 2024 -0400

    refactor!: return NC_SUCCESS when validating secret key

commit 718be80a4810b9352de7eb0707da54020aa6b649
Author: vnugent <public@vaughnnugent.com>
Date:   Mon May 27 14:52:41 2024 -0400

    fix: Properly build mbedtls & cmake fixes

commit a8a6efb2319f739e5faae550561dc27d9dd1e88d
Author: vnugent <public@vaughnnugent.com>
Date:   Sun May 26 17:39:40 2024 -0400

    chore: Update libs, reorder files, internalize private headers

commit 72e1b7be4031e2fd4d258fcf434ad049c0029201
Author: vnugent <public@vaughnnugent.com>
Date:   Sun May 26 13:39:08 2024 -0400

    fix: Add c++ extern prototypes in noscrypt.h

commit aeaac8d328b75911541be64d6f09d58fca294a08
Author: vnugent <public@vaughnnugent.com>
Date:   Sun May 26 11:47:17 2024 -0400

    refactor: Dep update, openssl chacha20 added

commit 86b02540cce6015cfe4a2a56499a9a2f45d4e368
Author: vnugent <public@vaughnnugent.com>
Date:   Sat May 18 12:24:17 2024 -0400

    refactor: Remove NCContext structure definition

commit d09d9330415d463ca19be9394b02ce11b3366f7e
Author: vnugent <public@vaughnnugent.com>
Date:   Mon May 13 22:33:50 2024 -0400

    fix: update mbedtls inline issue includes

commit 7838cb4bb15d4f453f92f56ece75e2b03986fe42
Author: vnugent <public@vaughnnugent.com>
Date:   Mon May 13 22:29:16 2024 -0400

    fix: force fPIC for secp256k1 targets

commit d76f7708bc6ae81a638ca708230ac9153ac754e2
Merge: aa8033d a526139
Author: vnugent <public@vaughnnugent.com>
Date:   Sun May 12 00:37:01 2024 -0400

    Merge branch 'master' into develop

commit aa8033d4dbfebeb72b6fd7a0cd218ebde0eb54dd
Author: vnugent <public@vaughnnugent.com>
Date:   Sun May 12 00:34:20 2024 -0400

    Final overview and test before tag

commit 4e3ead2cf1d3068e77f0959dfdc17e20e9102a0f
Merge: 2cee801 872c49d
Author: vnugent <public@vaughnnugent.com>
Date:   Mon May 6 22:08:09 2024 -0400

    Merge branch 'master' into develop

commit 2cee801979bfbcb3b0e53f592ce8c779b57cb679
Author: vnugent <public@vaughnnugent.com>
Date:   Mon May 6 22:02:39 2024 -0400

    Ensure static and dynamic libs get same args

commit f533694023133552d0d42933d779c95a5854343f
Author: vnugent <public@vaughnnugent.com>
Date:   Mon May 6 21:50:29 2024 -0400

    feat: CMake install & fetch-content test & updates

commit 940ff20348b13d0bc30d9e9f4289dd6de20b16ba
Author: vnugent <public@vaughnnugent.com>
Date:   Sun May 5 14:07:28 2024 -0400

    codeberg readonly push

commit b34ed055c0b7d143561ce8798e0a95313b9224bd
Merge: 0a40e20 e737556
Author: vnugent <public@vaughnnugent.com>
Date:   Sat May 4 14:06:45 2024 -0400

    Merge branch 'master' into develop

commit 0a40e209d03e8ff9b6f81cd5969d3e845c633bfc
Author: vnugent <public@vaughnnugent.com>
Date:   Sat May 4 13:55:19 2024 -0400

    ci: Force disable testing for win ci builds

commit 55fae189fffc86f07a3448370f0a746670819712
Author: vnugent <public@vaughnnugent.com>
Date:   Thu May 2 21:54:35 2024 -0400

    feat: Working and tested openssl impl & defaults

commit 6ff8bb11774c51fd341b7699a3938fd894995fbf
Author: vnugent <public@vaughnnugent.com>
Date:   Thu Apr 25 17:45:42 2024 -0400

    refactor: Finish support and testing for mbedtls

commit 7cb7a93de4f6f5e741bc5129e3d928e44f050930
Author: vnugent <public@vaughnnugent.com>
Date:   Tue Apr 23 18:19:31 2024 -0400

    refactor!: MbedTLS on Windows, switch to uint32

commit 30e8dda6cbea86bdee6d5dfe48514385d3b9f81b
Author: vnugent <public@vaughnnugent.com>
Date:   Tue Apr 23 14:48:05 2024 -0400

    refactor: Crypto dep redesign working on Windows

commit d09c6c1bd5da3e2d79351daeba304ca99976a726
Author: vnugent <public@vaughnnugent.com>
Date:   Thu Apr 18 00:28:51 2024 -0400

    refactor!: Pushing what I have to dev

commit 54e06ada7d624ed0d28c6a6db04a149708841bf8
Author: vnugent <public@vaughnnugent.com>
Date:   Sat Apr 13 01:24:00 2024 -0400

    fix: convert constants to hex, inline macro, ParseErrorCode

commit 4215e3100d9a0d23119080d09638fa5b60d0c6d4
Merge: d3328f4 7485aa5
Author: vnugent <public@vaughnnugent.com>
Date:   Wed Apr 3 18:26:30 2024 -0400

    Merge branch 'master' into develop

commit d3328f4152b22b28f24c43dda62464287f1efff5
Author: vnugent <public@vaughnnugent.com>
Date:   Wed Apr 3 18:22:56 2024 -0400

    build: Included dependency and versions in client builds

commit b11bc0bac955fd5c6db65f0da48456bf5e748805
Author: vnugent <public@vaughnnugent.com>
Date:   Wed Apr 3 18:10:08 2024 -0400

    fix: Fix c89 compatabilty comments and struct assignment

commit 9915bd41799a72413e6b400e150aa9f5fa797e25
Merge: 8e3d6ea 5184d7d
Author: vnugent <public@vaughnnugent.com>
Date:   Sat Mar 30 09:57:30 2024 -0400

    Merge branch 'master' into develop

commit 8e3d6ea5e3c83fe42cb904b6ccc4fe2b73f76aae
Author: vnugent <public@vaughnnugent.com>
Date:   Sat Mar 30 09:52:55 2024 -0400

    refactor!: Some api (struct) changes and updated tests

commit e88e8420520204e20802516f01d4488bb0b1d6ea
Merge: 490dfee 21f6c0a
Author: vnugent <public@vaughnnugent.com>
Date:   Sun Mar 3 15:02:34 2024 -0500

    Merge branch 'master' into develop

commit 490dfee4ef22479009627435c6ad728c3cbbab54
Author: vnugent <public@vaughnnugent.com>
Date:   Sun Mar 3 14:59:25 2024 -0500

    test: #3 tests for encryption/description and Macs

commit efa97490b7ed47f4e2f05bee52e2b33e14e439e6
Merge: 1b84e3c 120022a
Author: vnugent <public@vaughnnugent.com>
Date:   Sun Mar 3 14:55:48 2024 -0500

    merge master

commit 1b84e3c7c2e55b1ff9ffdd09b66873e11c131441
Author: vnugent <public@vaughnnugent.com>
Date:   Sat Mar 2 22:57:36 2024 -0500

    fix: #2 constent usage of sizeof() operator on struct types

commit 9de5a214c66adea0ef2d0bac63c59449de202a88
Author: vnugent <public@vaughnnugent.com>
Date:   Fri Mar 1 14:30:36 2024 -0500

    perf: avoid nc_key struct copy, cast and verify instead

commit b917b761120ed684af28d0707673ffadcf14b8fe
Author: vnugent <public@vaughnnugent.com>
Date:   Mon Feb 12 22:06:50 2024 -0500

    fix: found the constant time memcompare function

commit 9f85fff3b9f25da7410569ea94f994b88feb3910
Author: vnugent <public@vaughnnugent.com>
Date:   Fri Feb 9 22:48:35 2024 -0500

    feat: added/update MAC functions to sign or verify nip44 payload

commit aa5113741bb419b02d6ea416bba571fa3d65db46
Author: vnugent <public@vaughnnugent.com>
Date:   Wed Feb 7 01:37:53 2024 -0500

    add missing hmac-key output buffer

commit 55f47d22cc9ce4d1e22b70814d608c7ef3b1bbc9
Author: vnugent <public@vaughnnugent.com>
Date:   Sun Feb 4 21:08:13 2024 -0500

    simple bug fixes, and public api argument validation tests

commit 73c5a713fb164ae8b4ac8a891a8020e08eae0a3b
Author: vnugent <public@vaughnnugent.com>
Date:   Fri Feb 2 23:05:48 2024 -0500

    update api to return secpvalidate return code instead of internal return codes

commit 06c73004e1a39a7ea4ea3a89c22dee0f66adb236
Author: vnugent <public@vaughnnugent.com>
Date:   Fri Feb 2 19:25:17 2024 -0500

    change to lgpl license

commit 6e79fdb3b6b6739fc7797d47e55a7691306cf736
Author: vnugent <public@vaughnnugent.com>
Date:   Wed Jan 31 21:30:49 2024 -0500

    move validation macros, and optionally disable them

commit ac1e58837f1ba687939f78b5c03cadd346c10ddd
Author: vnugent <public@vaughnnugent.com>
Date:   Tue Jan 30 12:25:05 2024 -0500

    couple more tests, renable range checks, set flags for all projects

1 files changed, 14 insertions, 31 deletions

diff --git a/src/hkdf.c b/src/hkdf.c
index 0d91d14..7b0b822 100644
--- a/src/hkdf.c
+++ b/src/hkdf.c
@@ -21,23 +21,10 @@
 
 #include "hkdf.h"
 
-/* Include string for memmove */
-#include <string.h>
-
 #define HKDF_MIN(a, b) (a < b ? a : b)
 
 STATIC_ASSERT(HKDF_IN_BUF_SIZE > SHA256_DIGEST_SIZE, "HDK Buffer must be at least the size of the underlying hashing alg output")
 
-static _nc_fn_inline void ncWriteSpanS(span_t* span, uint32_t offset, const uint8_t* data, uint32_t size)
-{
-	DEBUG_ASSERT2(span != NULL, "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")
-
-	/* Copy data to span */
-	memmove(span->data + offset, data, size);
-}
-
 static _nc_fn_inline void debugValidateHandler(const struct nc_hkdf_fn_cb_struct* handler)
 {
 	DEBUG_ASSERT(handler != NULL)
@@ -55,16 +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);
 
@@ -72,18 +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));
+	/* span over counter value that points to the counter buffer */
+	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;
 		}
@@ -93,7 +79,7 @@ cstatus_t hkdfExpandProcess(
 			goto Exit;
 		}
 
-		if (handler->update(ctx, &counterSpan) != CSTATUS_OK)
+		if (handler->update(ctx, counterSpan) != CSTATUS_OK)
 		{
 			goto Exit;
 		}
@@ -109,18 +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(ncSpanGetSize(okm) - okmOffset, SHA256_DIGEST_SIZE);
 
 		DEBUG_ASSERT(tLen <= sizeof(t));
 
-		/* write the T buffer back to okm */
-		ncWriteSpanS(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 */