# `ExStorageServiceSdk.S3.UploadChecksum`
[🔗](https://github.com/gsmlg-opt/ex_storage_service/blob/v0.7.1/lib/ex_storage_service_sdk/s3/upload_checksum.ex#L1)

Serializable upload checksum contracts, locally retained part digests, and typed multipart completion.

# `acknowledge`

Rejects a provider's conflicting algorithm or checksum type without losing local selection.

# `completion`

Returns modeled completion fields and separately the expected provider checksum response.

# `copied_part`

Retains a selected server-copy digest without downloading or claiming to hash the source bytes.

# `initiation`

Builds initiation fields without incorrectly placing an object checksum on CreateMultipartUpload.

# `object`

Verifies single-PUT bytes, any explicit caller checksum, and provider-returned checksums.

# `part`

Hashes bounded Source chunks once for selected and returned algorithms, retaining local checksums even when absent remotely.

# `select`

Selects a JSON-safe checksum contract; multipart CRC64NVME defaults to FULL_OBJECT.

# `verify`

Validates every expected digest that is returned; absence never claims verification.

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*Consult [api-reference.md](api-reference.md) for complete listing*