awscrt.checksums

awscrt.checksums.crc32(input: bytes, previous_crc32: int = 0) → int

Perform a CRC32 (Ethernet, gzip) computation.

If continuing to update a running CRC, pass its value into previous_crc32. Returns an unsigned 32-bit integer.

awscrt.checksums.crc32c(input: bytes, previous_crc32c: int = 0) → int

Perform a Castagnoli CRC32c (iSCSI) computation. If continuing to update a running CRC, pass its value into previous_crc32c. Returns an unsigned 32-bit integer.

awscrt.checksums.crc64nvme(input: bytes, previous_crc64nvme: int = 0) → int

Perform a CRC64 NVME computation. If continuing to update a running CRC, pass its value into previous_crc64nvme. Returns an unsigned 64-bit integer.

awscrt.checksums.combine_crc32(crc32_result1: int, crc32_result2: int, data_length2: int) → int

Combine two CRC32 (Ethernet, gzip) checksums computed over separate data blocks.

This is equivalent to computing the CRC32 of the concatenated data blocks without having to re-scan the data.

Given:

crc1 = CRC32(data_block_A) crc2 = CRC32(data_block_B)

This function computes:

result = CRC32(data_block_A || data_block_B)

Parameters:

  • crc32_result1 – The CRC32 checksum of the first data block

  • crc32_result2 – The CRC32 checksum of the second data block

  • data_length2 – The length (in bytes) of the original data that produced crc32_result2. This is NOT the size of the checksum (which is always 4 bytes), but rather the size of the data block that was checksummed.

Returns:

The combined CRC32 checksum as if computed over the concatenated data

awscrt.checksums.combine_crc32c(crc32c_result1: int, crc32c_result2: int, data_length2: int) → int

Combine two CRC32C (Castagnoli, iSCSI) checksums computed over separate data blocks.

This is equivalent to computing the CRC32C of the concatenated data blocks without having to re-scan the data.

Given:

crc1 = CRC32C(data_block_A) crc2 = CRC32C(data_block_B)

This function computes:

result = CRC32C(data_block_A || data_block_B)

Parameters:

  • crc32c_result1 – The CRC32C checksum of the first data block

  • crc32c_result2 – The CRC32C checksum of the second data block

  • data_length2 – The length (in bytes) of the original data that produced crc32c_result2. This is NOT the size of the checksum (which is always 4 bytes), but rather the size of the data block that was checksummed.

Returns:

The combined CRC32C checksum as if computed over the concatenated data

awscrt.checksums.combine_crc64nvme(crc64nvme_result1: int, crc64nvme_result2: int, data_length2: int) → int

Combine two CRC64-NVME (CRC64-Rocksoft) checksums computed over separate data blocks.

This is equivalent to computing the CRC64-NVME of the concatenated data blocks without having to re-scan the data.

Given:

crc1 = CRC64_NVME(data_block_A) crc2 = CRC64_NVME(data_block_B)

This function computes:

result = CRC64_NVME(data_block_A || data_block_B)

Parameters:

  • crc64nvme_result1 – The CRC64-NVME checksum of the first data block

  • crc64nvme_result2 – The CRC64-NVME checksum of the second data block

  • data_length2 – The length (in bytes) of the original data that produced crc64nvme_result2. This is NOT the size of the checksum (which is always 8 bytes), but rather the size of the data block that was checksummed.

Returns:

The combined CRC64-NVME checksum as if computed over the concatenated data