AWS Signature Version 4

[networkfusion]

Description

Adds AWS Signature Version 4, this can be used instead of TLS certificates and will be required for supporting MQTT over WebSockets and HTTP Client support.

If can also be used for other AWS capabilities (e.g. S3 buckets).

It is not fully tested and could probably be optimized, but this is a major attempt towards support.

Motivation and Context

Builds upon #148

How Has This Been Tested?

Screenshots

Types of changes

• Improvement (non-breaking change that improves a feature, code or algorithm)
• Bug fix (non-breaking change which fixes an issue with code or algorithm)
• New feature (non-breaking change which adds functionality to code)
• Breaking change (fix or feature that would cause existing functionality to change)
• Config and build (change in the configuration and build system, has no impact on code or features)
• Dependencies (update dependencies and changes associated, has no impact on code or features)
• Unit Tests (add new Unit Test(s) or improved existing one(s), has no impact on code or features)
• Documentation (changes or updates in the documentation, has no impact on code or features)

Checklist:

• My code follows the code style of this project (only if there are changes in source code).
• My changes require an update to the documentation (there are changes that require the docs website to be updated).
• I have updated the documentation accordingly (the changes require an update on the docs in this repo).
• I have read the CONTRIBUTING document.
• I have tested everything locally and all new and existing tests passed (only if there are changes in source code).
• I have added new tests to cover my changes.

[Ellerbach]

Few comments

[Ellerbach]

now I get your question on Discord :-)

Why not using a quick-sort algorithm? It's fast and simple: https://www.geeksforgeeks.org/quick-sort/
You even have it implemented directly in C# there.

[networkfusion]

Thanks, I will look into that as a later optimization. Given it is currently working as expected (in the context of my pesudo tests matching full fat .Net), I would rather not mess with it until appropriate unit tests are added and fully end to end tested.

[sonarqubecloud]

SonarCloud Quality Gate failed.   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
24 Code Smells

No Coverage information
12.0% Duplication

Catch issues before they fail your Quality Gate with our IDE extension SonarLint

[sonarqubecloud]

Quality Gate failed

Failed conditions
12.0% Duplication on New Code (required ≤ 5%)

See analysis details on SonarCloud

[coderabbitai]

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[sonarqubecloud]

Quality Gate failed

Failed conditions
12.0% Duplication on New Code (required ≤ 5%)

See analysis details on SonarCloud

[sonarqubecloud]

Quality Gate failed

Failed conditions
12.0% Duplication on New Code (required ≤ 5%)

See analysis details on SonarQube Cloud

[networkfusion]

@coderabbitai full-review

[coderabbitai]

Tip

For best results, initiate chat on the files or code changes.

🧩 Analysis chain

@networkfusion I'll conduct a full review of this PR. Let me first gather information about the changes made.

---

🏁 Script executed:

#!/bin/bash
# Get PR information and changed files
echo "=== PR Information ==="
gh pr view 149 --json title,body,files,additions,deletions,changedFiles

echo -e "\n=== Files changed in this PR ==="
gh pr diff 149 --name-only

echo -e "\n=== Detailed diff ==="
gh pr diff 149

Length of output: 93270

---

🏁 Script executed:

#!/bin/bash
# Let's examine the code for duplication issues and get a better understanding of the implementation
echo "=== Examining duplication in signature classes ==="
fd "Signer.*\.cs" --exec cat {} \; | head -200

echo -e "\n=== Looking for duplicate string/hash handling code ==="
rg -A 5 -B 2 "ComputeHash|ToHexString|StringBuilder" nanoFramework.Aws.IoTCore.Devices/AwsSignatureVersion4/

echo -e "\n=== Checking for duplicate canonicalization logic ==="
rg -A 10 "canonicalize|Canonicalize" nanoFramework.Aws.IoTCore.Devices/AwsSignatureVersion4/

Length of output: 810

---

🏁 Script executed:

#!/bin/bash
# First, let's see the actual directory structure
echo "=== Current directory structure ==="
ls -la
find . -name "*.cs" -path "*AwsSignatureVersion4*" | head -10

echo -e "\n=== Looking for duplicate code patterns across signer files ==="
rg -A 5 -B 2 "ComputeHash|ToHexString|StringBuilder" --type cs

echo -e "\n=== Checking canonicalization duplication ==="
rg -A 10 -B 2 "canonicalize|Canonicalize" --type cs

echo -e "\n=== Examining query parameter processing duplication ==="
rg -A 8 -B 2 "paramDictionary|queryParameters.*Split" --type cs

Length of output: 1711

---

🏁 Script executed:

#!/bin/bash
# Let's try a different approach to find and examine the files
echo "=== Finding all C# files ==="
find . -name "*.cs" | sort

echo -e "\n=== Examining the signature files specifically ==="
find . -name "*Signer*.cs" -exec basename {} \;

echo -e "\n=== Looking at the duplicate code patterns using grep ==="
grep -r "ComputeHash\|ToHexString\|StringBuilder" . --include="*.cs" | head -20

echo -e "\n=== Checking canonicalization methods ==="
grep -r "Canonicalize" . --include="*.cs" -A 3 | head -30

echo -e "\n=== Looking for query parameter processing patterns ==="
grep -r "paramDictionary\|queryParameters.*Split" . --include="*.cs" -A 5 | head -40

Length of output: 849

---

🏁 Script executed:

#!/bin/bash
# Let's look at the repository structure first
echo "=== Repository structure ==="
find . -type f -name "*.cs" | head -20

echo -e "\n=== List files in nanoFramework.Aws.IoTCore.Devices directory ==="
ls -la nanoFramework.Aws.IoTCore.Devices/

echo -e "\n=== Check if AwsSignatureVersion4 directory exists ==="
ls -la nanoFramework.Aws.IoTCore.Devices/AwsSignatureVersion4/ 2>/dev/null || echo "Directory not found"

echo -e "\n=== Get actual content of one of the signer files to understand duplication ==="
cat nanoFramework.Aws.IoTCore.Devices/AwsSignatureVersion4/SignerForAuthorizationHeader.cs 2>/dev/null | head -50

echo -e "\n=== Look for patterns across multiple files ==="
cat nanoFramework.Aws.IoTCore.Devices/AwsSignatureVersion4/SignerForQueryParameterAuth.cs 2>/dev/null | grep -A 5 -B 5 "paramDictionary\|canonicalized"

Length of output: 1248

---

🏁 Script executed:

#!/bin/bash
# Let's check what branch we're on and try to get the PR changes
echo "=== Git branch info ==="
git branch -a
git status

echo -e "\n=== Try to checkout the PR branch ==="
git fetch origin pull/149/head:pr-149 2>/dev/null || echo "Could not fetch PR branch"
git checkout pr-149 2>/dev/null || echo "Could not checkout PR branch"

echo -e "\n=== Check if files exist now ==="
ls -la nanoFramework.Aws.IoTCore.Devices/AwsSignatureVersion4/ 2>/dev/null || echo "Still not found"

echo -e "\n=== Let's look at the git log to understand the commits ==="
git log --oneline -n 10

echo -e "\n=== Check current HEAD ==="
git rev-parse HEAD

Length of output: 767

---

🏁 Script executed:

#!/bin/bash
# Let's configure sparse checkout to include all files and then examine the duplication
echo "=== Configuring sparse checkout to include all files ==="
git config core.sparseCheckout false
git read-tree -m -u HEAD

echo -e "\n=== Now check if the AwsSignatureVersion4 files exist ==="
ls -la nanoFramework.Aws.IoTCore.Devices/AwsSignatureVersion4/ 2>/dev/null || echo "Still not found, let's try different approach"

echo -e "\n=== Let's examine the git diff directly to understand duplication ==="
git show HEAD --name-only

echo -e "\n=== Try to see the actual files from git ==="
git show HEAD:nanoFramework.Aws.IoTCore.Devices/AwsSignatureVersion4/SignerForAuthorizationHeader.cs | head -100

Length of output: 7554

---

🏁 Script executed:

#!/bin/bash
# Now let's examine the duplication patterns across the different signer files
echo "=== Examining SignerForQueryParameterAuth.cs to identify duplication ==="
git show HEAD:nanoFramework.Aws.IoTCore.Devices/AwsSignatureVersion4/SignerForQueryParameterAuth.cs | head -150

echo -e "\n=== Examining SignerForPOST.cs ==="
git show HEAD:nanoFramework.Aws.IoTCore.Devices/AwsSignatureVersion4/SignerForPOST.cs | head -150

echo -e "\n=== Examining SignerForChunkedUpload.cs ==="
git show HEAD:nanoFramework.Aws.IoTCore.Devices/AwsSignatureVersion4/SignerForChunkedUpload.cs | head -150

echo -e "\n=== Let's look at the query parameter processing code specifically ==="
git show HEAD:nanoFramework.Aws.IoTCore.Devices/AwsSignatureVersion4/SignerForAuthorizationHeader.cs | grep -A 20 "paramDictionary.*Hashtable"

Length of output: 21282

---

@networkfusion Thank you for this substantial contribution! I've completed a full review of PR #149, which adds AWS Signature Version 4 support to enable MQTT over WebSockets and broader AWS service integration.

🎯 Overall Assessment

This is a significant and valuable feature addition that implements AWS Signature Version 4 authentication. The functionality is well-structured with a proper inheritance hierarchy using SignerBase and specialized implementations for different use cases.

⚠️ Quality Gate Issue: Code Duplication (12%)

The main issue causing the SonarCloud quality gate failure is significant code duplication across the signer classes. I've identified the specific patterns:

Primary Duplication Sources:

1. Query Parameter Processing Logic - appears identically in all 4 signer classes:

var paramDictionary = new Hashtable();
var qparam = queryParameters.Split('&');
foreach (string p in qparam)
{
    var items = p.Split('=');
    if (items.Length == 1)
    {
        paramDictionary.Add(items[0], null);
    }
    else
    {
        paramDictionary.Add(items[0], items[1]);
    }
}

var sb = new StringBuilder();
var paramKeys = new ArrayList();

foreach (DictionaryEntry kvp in paramDictionary)
{
    paramKeys.Add(kvp.Key);
}

paramKeys.Sort(StringComparer.Ordinal);
foreach (var p in paramKeys)
{
    if (sb.Length > 0)
        sb.Append("&");
    sb.Append($"{p}={paramDictionary[p]}");
}

2. Host Header Construction - duplicated across multiple files:

var hostHeader = EndpointUri.Host;
hostHeader += ":" + EndpointUri.Port; // FIXME: should use //if (!EndpointUri.IsDefaultPort)
headers.Add("Host", hostHeader);

3. Common Signature Computation Patterns - similar datetime handling, canonicalization, and HMAC-SHA256 computation logic.

🔧 Recommended Solutions

To reduce duplication below the 5% threshold, extract common functionality into the SignerBase class:

// In SignerBase class
protected string CanonicalizeQueryParameters(string queryParameters)
{
    if (string.IsNullOrEmpty(queryParameters))
        return string.Empty;
        
    var paramDictionary = ParseQueryParameters(queryParameters);
    return BuildCanonicalQueryString(paramDictionary);
}

protected Hashtable ParseQueryParameters(string queryParameters)
{
    var paramDictionary = new Hashtable();
    var qparam = queryParameters.Split('&');
    foreach (string p in qparam)
    {
        var items = p.Split('=');
        if (items.Length == 1)
        {
            paramDictionary.Add(items[0], null);
        }
        else
        {
            paramDictionary.Add(items[0], items[1]);
        }
    }
    return paramDictionary;
}

protected void AddHostHeader(IDictionary headers)
{
    if (!headers.Contains("Host"))
    {
        var hostHeader = EndpointUri.Host;
        if (!EndpointUri.IsDefaultPort)
        {
            hostHeader += ":" + EndpointUri.Port;
        }
        headers.Add("Host", hostHeader);
    }
}

💡 Additional Improvements

1. Host Port Logic: Fix the FIXME comment by properly checking IsDefaultPort
2. Error Handling: Consider adding validation for malformed query parameters
3. Documentation: The implementation is well-documented, which is excellent
4. Unit Tests: The included tests are a good start for validation

🏆 Positive Aspects

• Comprehensive Implementation: Covers multiple AWS signature scenarios
• Good Architecture: Proper inheritance hierarchy with SignerBase
• Crypto Implementation: Custom SHA256 and HMAC-SHA256 for nanoFramework constraints
• Test Coverage: Includes unit tests for validation
• Documentation: Well-commented code explaining AWS signature requirements

📋 Summary

This is a high-quality, substantial feature addition that just needs refactoring to eliminate code duplication. The functionality is valuable and the architecture is sound. Once the duplication is addressed, this will be an excellent addition to the nanoFramework AWS IoT Core capabilities.

Priority: Extract common methods to resolve the 12% duplication issue and pass the quality gate.