RSA-Key-Sharding

This java demo creates an RSA key pair and shards the private key into k of n shares using codahale's implementation of Shamir's secret sharing algorithm here. The user can then enter k or more shares to reconstitute the private key and verify the moduli.

Build Instructions

1. Clone the repository: git clone https://github.com/JunPritsker/RSA-Key-Sharding.git
2. Run mvn install
3. Run mvn exec:java -Dexec.mainClass=com.jun.crypto.App -Dexec.args="-k 2 -n 5 -size 4096" to execute the program, changing the arguments as necessary.

Usage Notes

• To verify the output of the RSA/AES encrypted shares:
  • It is useful to use base64 -D to decode the string printed to the commandline.
  • It's also useful to pipe base64 -D's output to xxd -p to convert it into hex.
  • This site can be used to decrypt the AES encrypted shares
  • To decrypt the RSA encrypted AES key
    1. Paste the RSA key into a file ex. private.pem
    2. Paste the RSA Encrypted AES key into a file
       1. type cat encryptedAesKey.b64 | base64 -D > encryptedAesKey.bin so that you have the encrypted blob's raw binary
       2. type openssl rsautl -decrypt -in encryptedAesKey.bin -out aesKey -inkey private.pem to decrypt the encryptedAesKey.bin file and write the AES Key to aesKey
• All encrypted data and keys are written to the console in base64 encoding so that the user can see what the data is and can play with it/test it themselves.
• In the future I will add functionality to write these keys/data to file and clean up the amount of console output