Upload file to S3 bucket without AWS CLI module

S3upload.ps1

# ============================================
# 1. Set your values here
# ============================================

$AccessKey   = 'AKIAY…..'
$SecretKey   = 'xxxx'
$Region      = "xxx"
$BucketName  = "bucketname"
$Prefix      = "packages"
$LocalFile   = 'C:\testfile.zip'

# ============================================
# 2. Build S3 URL & key
# ============================================

$fileName = [IO.Path]::GetFileName($LocalFile)
if ([string]::IsNullOrWhiteSpace($Prefix)) {
    $ObjectKey = $fileName
} else {
    $ObjectKey = ($Prefix.TrimEnd("/") + "/" + $fileName)
}

$AWSHost = "$BucketName.s3.$Region.amazonaws.com"
$Url  = https://$AWSHost/$ObjectKey

# Read file into memory
$Body = [IO.File]::ReadAllBytes($LocalFile)

$sha256 = [System.Security.Cryptography.SHA256]::Create()
$hashBytes = $sha256.ComputeHash($Body)
$sha256.Dispose()

$payloadHashHex = ([System.BitConverter]::ToString($hashBytes)).Replace("-", "").ToLowerInvariant()

# ============================================
# 3. Build SigV4 Canonical Request
# ============================================

#optional - remove setting ServicePointManager if not required
[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12

$head = Invoke-WebRequest -Method Get -Uri https://s3.amazonaws.com/ -UseBasicParsing
$serverDate = [DateTime]::Parse($head.Headers["Date"]).ToUniversalTime()
$amzDate   = $serverDate.ToString("yyyyMMddTHHmmssZ")
$dateStamp = $serverDate.ToString("yyyyMMdd")
$Method = "PUT"
$CanonicalUri = "/" + $ObjectKey
$canonicalQueryString = ""
$CanonicalHeaders = "host:$AWSHost`n" + "x-amz-content-sha256:$payloadHashHex`n" + "x-amz-date:$amzDate`n"
$SignedHeaders = "host;x-amz-content-sha256;x-amz-date"
$PayloadHash = $payloadHashHex
$CanonicalRequest = @"
$Method
$CanonicalUri
$canonicalQueryString
$CanonicalHeaders
$SignedHeaders
$PayloadHash
"@
# SHA256 hash
$CanonicalRequestHash = [BitConverter]::ToString((New-Object Security.Cryptography.SHA256Managed).ComputeHash([Text.Encoding]::UTF8.GetBytes($CanonicalRequest))).Replace("-", "").ToLower()

# ============================================
# 4. String To Sign
# ============================================

$CredentialScope = "$dateStamp/$Region/s3/aws4_request"
$StringToSign = @"
AWS4-HMAC-SHA256
$amzDate
$CredentialScope
$CanonicalRequestHash
"@

# ============================================
# 5. Generate AWS Signature V4
# ============================================

function Hmac([byte[]]$Key, [string]$Data) {
    $h = New-Object Security.Cryptography.HMACSHA256
    $h.Key = $Key
    return $h.ComputeHash([Text.Encoding]::UTF8.GetBytes($Data))
}

$kSecret  = [Text.Encoding]::UTF8.GetBytes("AWS4$SecretKey")
$kDate    = Hmac $kSecret  $dateStamp
$kRegion  = Hmac $kDate    $Region
$kService = Hmac $kRegion  "s3"
$kSigning = Hmac $kService "aws4_request"
$Signature = [BitConverter]::ToString((New-Object Security.Cryptography.HMACSHA256 -Property @{ Key = $kSigning }).ComputeHash([Text.Encoding]::UTF8.GetBytes($StringToSign))).Replace("-", "").ToLower()

# ============================================
# 6. Prepare headers
# ============================================

$Authorization = "AWS4-HMAC-SHA256 Credential=$AccessKey/$CredentialScope, SignedHeaders=$SignedHeaders, Signature=$Signature"
$Headers = @{
    "x-amz-date"            = $amzDate
    "x-amz-content-sha256"  = $payloadHashHex
    "Authorization"         = $Authorization
}

Write-Host "Uploading $LocalFile → s3://$BucketName/$ObjectKey"
# ============================================
# 7. Upload using raw HTTPS REST call
# ============================================

try {
    $resp = Invoke-RestMethod -Uri $Url -Method PUT -Headers $Headers -Body $Body
    Write-Host "Upload complete!"
    $resp
}
catch {
    Write-Warning "Upload failed: $($_.Exception.Message)"
    if ($_.Exception.Response -and $_.Exception.Response.GetResponseStream()) {
        $reader = New-Object IO.StreamReader ($_.Exception.Response.GetResponseStream())
        $errorBody = $reader.ReadToEnd()
        Write-Host "----- AWS Error Body -----"
        Write-Host $errorBody
    }
    throw
}