Implementing Sha256

[Wictorian]

https://blog.boot.dev/cryptography/how-sha-2-works-step-by-step-sha-256/ I'm following this guide and it's going well but sometimes it is hard to understand.

Especially 2nd part of step 5

 

 

[Sauron]

Your data must be divided in 32 bit words, meaning data blocks of 32 bits. These blocks should be placed in an array. That array should also contain 48 more 32 bit blocks that only contain 0s. The result is an array of 64 32-bit data blocks.

[Wictorian]

7 hours ago, Sauron said:

Your data must be divided in 32 bit words, meaning data blocks of 32 bits. These blocks should be placed in an array. That array should also contain 48 more 32 bit blocks that only contain 0s. The result is an array of 64 32-bit data blocks.

What if there are more blocks though?

[wanderingfool2]

1 hour ago, Wictorian said:

What if there are more blocks though?

 

Step 1 was essentially creating a 512 bit chunk (or rather things divisible by 512) from your input data.

Step 5 is processing a 512 bit chunk.  So you shouldn't be able to have "more blocks"

 

The 512 bits gets divided into 32 bit sub-chunks (16 total). It is saying add 48 more totals of 32 bit sub-chunks....so you end up with 64 total sub-chunks that are 32 bit.

 

So you can't have more than that.

 

[Wictorian]

11 minutes ago, wanderingfool2 said:

 

Step 1 was essentially creating a 512 bit chunk (or rather things divisible by 512) from your input data.

Step 5 is processing a 512 bit chunk.  So you shouldn't be able to have "more blocks"

 

The 512 bits gets divided into 32 bit sub-chunks (16 total). It is saying add 48 more totals of 32 bit sub-chunks....so you end up with 64 total sub-chunks that are 32 bit.

 

So you can't have more than that.

 

Oh ok so I am supposed to do this individually for each chunk.

[Sauron]

1 hour ago, Wictorian said:

What if there are more blocks though?

You repeat step 5 for those blocks

13 minutes ago, Wictorian said:

Oh ok so I am supposed to do this individually for each chunk.

yes