SSL write/read performance

Matt Caswell matt at
Wed Apr 10 10:10:20 UTC 2019

On 10/04/2019 11:03, valmiki wrote:
>>> Hi All,
>>> I'm trying to understand server and client code over tcp using openssl.
>>> How does the flow work when we do SSL_write or SSL_read.
>>> SSL_write -> send buffer to kernel crypto subsystem -> take encrypted buffer and send it over network socket.
>>> Is the above understanding correct ?
>> No, this isn't correct. All crypto is done in user space* using libcrypto.
>> Matt
>> * Actually there is a new option in master where the kernel does the TLS
>> encryption/decryption - but it is not on by default, and if used the kernel does
>> the IO too.
>> Thanks Matt.
>> So only one context switch happens, which is sending buffer to networking 
>> socket ?



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