[tpm2] Re: Ecrypting and decrypting a file using a TPM2

[Petr Gotthard <petr.gotthard at centrum.cz>]

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Hi Dawn,
there are code samples in the OpenSSL documentation.
 
First, you need OSSL_PROVIDER_load as shown here
https://github.com/tpm2-software/tpm2-openssl/blob/master/test/selftest.c
 
 
Then, to load EVP_PKEY from the TPM you need the OSSL_STORE* functions and the shipplet from here
https://github.com/tpm2-software/tpm2-openssl/issues/26#issuecomment-1057929799
 
 
Finally, I believe the OpenSSL routines to use for file encrypting are EVP_Seal* and EVP_Open*
https://wiki.openssl.org/index.php/EVP_Asymmetric_Encryption_and_Decryption_of_an_Envelope
these work exactly like Steven suggested.
 
I you face any troubles, just let me know.
 
 
Petr
 
______________________________________________________________
> Od: dawn.howe(a)alten.com
> Komu: tpm2(a)lists.01.org
> Datum: 15.06.2022 21:29
> Předmět: [tpm2] Re: Ecrypting and decrypting a file using a TPM2
>
Petr:
 Thanks so much for the suggestion.  I was able to encrypt and decrypt my files based on the pattern in https://github.com/tpm2-software/tpm2-openssl/blob/master/test/cipher_aes128_cbc.sh <https://github.com/tpm2-software/tpm2-openssl/blob/master/test/cipher_aes128_cbc.sh>.  I think I can accomplish what I want with some system calls to openssl.
 
 The code I'm writing is in C++. Is there a way to replace the system call to openssl with a c++ library call (perhaps that takes a provider parameter)?
 
 i.e. Replace the following with a C++ library call 
 openssl enc -provider tpm2 -aes128 -e -K $KEY -iv $IV -in testdata -out testdata.enc
 
 I'd love to see a code sample if you have one.
 
 thanks,
 Dawn
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