Supported checksums

Checksums are critical components in ensuring data integrity within object storage systems. They are calculated values, typically a hash or a cyclic redundancy check (CRC), obtained from the content of an object. By comparing the stored checksum with one recalculated during data retrieval, storage systems can detect and often correct errors caused by corruption, transmission issues, or hardware failures.

Supported checksum algorithmsLink to this anchor

Scaleway Object Storage supports several checksum algorithms that allow you to verify the integrity of your objects:

• CRC32: a non-cryptographic checksum that generates a 32-bit hash value used to detect errors in data transmission by applying a specific cyclic redundancy check (CRC) algorithm.

• CRC32C: a checksum algorithm that uses the Castagnoli polynomial for improved error-detection performance over the standard CRC32.

• SHA-1: a cryptographic Secure Hash Algorithm (SHA) that generates a 160-bit (20-byte) hash value from input data.

• SHA-256: a cryptographic Secure Hash Algorithm that generates a 256-bit unique hash value, preferred for modern security protocols due to SHA-1 vulnerabilities.

• CRC-64/NVME (CRC64NVME): a 64-bit cyclic redundancy check algorithm specifically designed for data integrity verification in NVMe (Non-Volatile Memory Express) storage devices. This algorithm does not support composite checksums.

Full object and composite checksum typesLink to this anchor

Scaleway Object Storage supports two types of checksums:

• Full object checksums: cryptographic hash values calculated over the entire content of an object to verify its integrity and detect any corruption or unauthorized changes.

• Composite object checksums: hash values calculated by combining the checksums of individual parts or segments of a multipart object, allowing verification of the integrity of the entire object assembled from its parts.

The table below shows the checksum types supported by each algorithm for multipart uploads: