Hi,

The bad MAC (message authentication context) error is OpenSSL detecting a 
problem with the integrity of your communication layer.  Normally this means 
that your packets are out of order or that you have lost some bytes.

Try doing a simple checksum of your encrypted data client and server side.  
You'll probably find that you've miscalculated a buffer size or something.  
Maybe you've got some packet fragmentation...

David L


> Message Received: Oct 03 2013, 07:30 PM
> From: "Perrow, Graeme" <[email protected]>
> To: "[email protected]" <[email protected]>
> Cc: 
> Subject: decryption failed or bad record mac error on SSL connection
> 
> 
> I am seeing an error on some SSL connections between two different Windows 
> machines. Both are using OpenSSL 1.0.1e. The error is:
> 
> 3612:error:1408F119:SSL routines:SSL3_GET_RECORD:decryption failed or bad 
> record mac:.\ssl\s3_pkt.c:484:
> 
> This shows up on a connection (the TLS client, if it matters) while 
> downloading a large amount of data (a 70 MB file). The amount of data I can 
> send/receive before the error happens differs but is rarely more than about 
> 400 KB. Some googling showed many reports saying this was related to AES-NI, 
> and that I should disable it using the OPENSSL_ia32cap environment variable, 
> but this did not fix the problem. Plus it seems that my version of OpenSSL 
> should contain the fix anyway.
> 
> I'm using SSLv23_server_method() and SSL23_client_method() on the server and 
> client respectively. The opts I'm using are SSL_OP_ALL|SSL_OP_NO_SSLv2, and 
> the ciphers are "AES256-SHA:AES128-SHA:RC4-MD5".
> 
> Anyone know what else might cause this problem or how I can avoid it?
> 
> Graeme Perrow
> 
> 
> 
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