feat: add checksum_algorithm configuration option

README.md

@@ -80,6 +80,12 @@ version numbers.
     for S3 compatible providers. The default behaviour is to require checksum
     verification.
 
+* `checksum_algorithm`: *Optional.* Specifies the checksum algorithm to use
+    when uploading objects to S3. Valid values are `CRC32`, `CRC32C`, `SHA1`,
+    `SHA256`, or `CRC64NVME`. If not specified, S3 will use its default algorithm.
+    This setting is ignored if `skip_s3_checksums` is set to `true`. Note that
+    not all S3-compatible providers support all algorithms.
+
 ### File Names
 
 One of the following two options must be specified:

cmd/check/main.go

@@ -33,6 +33,7 @@ func main() {
 		request.Source.DisableSSL,
 		request.Source.UsePathStyle,
 		request.Source.SkipS3Checksums,
+		request.Source.ChecksumAlgorithm,
 	)
 	if err != nil {
 		s3resource.Fatal("error creating s3 client", err)

cmd/in/main.go

@@ -45,6 +45,7 @@ func main() {
 		request.Source.DisableSSL,
 		request.Source.UsePathStyle,
 		request.Source.SkipS3Checksums,
+		request.Source.ChecksumAlgorithm,
 	)
 	if err != nil {
 		s3resource.Fatal("error creating s3 client", err)

cmd/out/main.go

@@ -40,6 +40,7 @@ func main() {
 		request.Source.DisableSSL,
 		request.Source.UsePathStyle,
 		request.Source.SkipS3Checksums,
+		request.Source.ChecksumAlgorithm,
 	)
 	if err != nil {
 		s3resource.Fatal("error creating s3 client", err)

integration/integration_suite_test.go

@@ -88,6 +88,7 @@ func getSessionTokenS3Client(awsConfig *aws.Config) (*s3.Client, s3resource.S3Cl
 		false,
 		pathStyle,
 		skipS3Checksums,
+		"",
 	)
 	Ω(err).ShouldNot(HaveOccurred())
 
@@ -145,6 +146,7 @@ var _ = SynchronizedBeforeSuite(func() []byte {
 			false,
 			pathStyle,
 			skipS3Checksums,
+			"",
 		)
 		Ω(err).ShouldNot(HaveOccurred())
 	}

models.go

@@ -28,6 +28,7 @@ type Source struct {
 	DisableMultipart     bool   `json:"disable_multipart"`
 	UsePathStyle         bool   `json:"use_path_style"`
 	SkipS3Checksums      bool   `json:"skip_s3_checksums"`
+	ChecksumAlgorithm    string `json:"checksum_algorithm"`
 }
 
 func (source Source) IsValid() (bool, string) {
@@ -56,6 +57,24 @@ func (source Source) IsValid() (bool, string) {
 		return false, "please specify initial_version or initial_path if initial content is set"
 	}
 
+	// Validate checksum algorithm if specified
+	if source.ChecksumAlgorithm != "" {
+		validAlgorithms := map[string]bool{
+			"CRC32":     true,
+			"CRC32C":    true,
+			"SHA1":      true,
+			"SHA256":    true,
+			"CRC64NVME": true,
+		}
+		if !validAlgorithms[source.ChecksumAlgorithm] {
+			return false, "checksum_algorithm must be one of: CRC32, CRC32C, SHA1, SHA256, CRC64NVME"
+		}
+
+		if source.SkipS3Checksums {
+			return false, "checksum_algorithm cannot be used when skip_s3_checksums is true"
+		}
+	}
+
 	return true, ""
 }
 

s3client.go

@@ -62,6 +62,7 @@ type UploadFileOptions struct {
 	KmsKeyId             string
 	ContentType          string
 	DisableMultipart     bool
+	ChecksumAlgorithm    string
 }
 
 func NewUploadFileOptions() UploadFileOptions {
@@ -75,6 +76,7 @@ func NewS3Client(
 	awsConfig *aws.Config,
 	endpoint string,
 	disableSSL, usePathStyle, skipS3Checksums bool,
+	checksumAlgorithm string,
 ) (S3Client, error) {
 	s3Opts := []func(*s3.Options){}
 
@@ -100,6 +102,9 @@ func NewS3Client(
 				o.RequestChecksumCalculation = aws.RequestChecksumCalculationWhenRequired
 				o.ResponseChecksumValidation = aws.ResponseChecksumValidationWhenRequired
 			}
+			if checksumAlgorithm != "" {
+				o.RequestChecksumCalculation = aws.RequestChecksumCalculationWhenSupported
+			}
 		})
 	}
 
@@ -342,6 +347,9 @@ func (client *s3client) UploadFile(bucketName string, remotePath string, localPa
 	if options.ContentType != "" {
 		uploadInput.ContentType = aws.String(options.ContentType)
 	}
+	if options.ChecksumAlgorithm != "" {
+		uploadInput.ChecksumAlgorithm = types.ChecksumAlgorithm(options.ChecksumAlgorithm)
+	}
 
 	uploadOutput, err := uploader.Upload(context.TODO(), uploadInput)
 	if err != nil {