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X-CUBE-CRYPTOLIB AES CTR

Question asked by surleau.frederic on May 14, 2018
Latest reply on May 15, 2018 by surleau.frederic

Hi,

Does anyone knows how the counter is handled in AES_CTR_Encrypt_Init() / AES_CTR_Encrypt_Append().

 

I suppose it is somewhere in the IV, but the documentation does not talk about it.

 

The examples use an IV initialised at 0xF0, 0xF1, ..., 0xFF with a nice comment :

"Third parameter is NULL because CTR doesn't use any IV".

 

If the counter is not in the IV where is it ? How can I modify it ?

 

Is it a 16 bytes big integer ?

A 32 bit integer ?

Endianness ?

 

Regards,

Fred.

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