wolfssl-examples/pk/enc-through-sign-rsa

An example that takes a simulated aes key (a string of 32-bytes / 256-bits) and encrypts it using RSA SSL Sign in wolfSSL. Keep in mind this is not a TRUE RSA ENCRYPT and will likely not inter-op with other libraries that offer a RSA_PRIVATE_ENCRYPT type API.

This is a true SIGN operation.

However this will achieve, for fixed-length inputs, an encrypt via sign of the input data.

Then using a verify operation you can un-pad and recover the original input using the public key.

This example was created as result of a question asked on our public forums here: https://www.wolfssl.com/forums/topic1117-does-wolfssl-support-using-rsa-private-key-to-encrypt-object-data.html

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BUILDING:

configure wolfSSL library (https://wolfssl.com/download/) (https://github.com/wolfssl/wolfssl.git) with this option:

./configure CFLAGS="-DUSE_CERT_BUFFERS_2048"
make
sudo make install

Once the wolfSSL libraries are configured and installed the from this directory run the build.sh script which will generate the two applications

rsa-private-encrypt-app rsa-public-decrypt-app

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USING:

./rsa-private-encrypt-app

This will output the file "encryptedAesKey" which will contain the RSA "signed" (encrypted and padded) AES KEY that we specified on line 33 of the application "rsa-private-encrypt-app.c".

33     const byte in[] = "Thisismyfakeaeskeythatis32bytes!";

Now run

./rsa-public-decrypt-app

This will open the file specified on line 32 of the application "rsa-public-decrypt-app.c" and "verify" (unpad and decrypt) the file using the public RSA key.

 32     char fName[] = "encryptedAesKey";

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If you have any questions/concerns/feedback please contact wolfSSL at info@wolfssl.com or support@wolfssl.com anytime!