module Meshchat::Encryption::DEFAULT_ENCRYPTOR
Using AES266-CBC with RSA
Docs on AES ruby-doc.org/stdlib-2.0.0/libdoc/openssl/rdoc/OpenSSL/Cipher.html
Constants
- AES_MODE
Use Cipher Block Chaining en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Cipher_Block_Chaining_.28CBC.29
Public Instance Methods
decrypt(msg, private_key)
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Split the string in to the AES key and the encrypted message
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Decrypt the AES key using the private key
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Decrypt the message using the AES key
# File lib/meshchat/encryption/aes_rsa.rb, line 45 def decrypt(msg, private_key) # 1 rsa_encrypted_aes_key = msg[0..255] # 256 bits rsa_encrypted_aes_iv = msg[256..511] # next 256 bits aes_encrypted_message = msg[512..msg.length] # 2 rsa_decryptor = OpenSSL::PKey::RSA.new private_key aes_key = rsa_decryptor.private_decrypt rsa_encrypted_aes_key aes_iv = rsa_decryptor.private_decrypt rsa_encrypted_aes_iv # 3 decipher = OpenSSL::Cipher::AES256.new(AES_MODE) decipher.decrypt decipher.key = aes_key decipher.iv = aes_iv decipher.update(aes_encrypted_message) + decipher.final end
encrypt(msg, public_key)
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Generate random AES key to encrypt message
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Use Public Key to encrypt AES Key
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Prepend encrypted AES key to the encrypted message
Output message format will look like the following:
{RSA Encrypted AES Key}{RSA Encrypted IV}{AES Encrypted Message}
# File lib/meshchat/encryption/aes_rsa.rb, line 22 def encrypt(msg, public_key) # 1 cipher = OpenSSL::Cipher::AES256.new(AES_MODE) cipher.encrypt aes_key = cipher.random_key aes_iv = cipher.random_iv aes_encrypted_message = cipher.update(msg) # pad, because of how CBC works padding = cipher.final encrypted = aes_encrypted_message + padding # 2 rsa_encryptor = OpenSSL::PKey::RSA.new public_key rsa_encrypted_aes_key = rsa_encryptor.public_encrypt(aes_key) rsa_encrypted_aes_iv = rsa_encryptor.public_encrypt(aes_iv) # 3 rsa_encrypted_aes_key + rsa_encrypted_aes_iv + encrypted end