RSA code: Difference between revisions

[[wp:RSA|RSA]] code is used to encode secret messages. It is named after the 3 men who first published it, Rivest, Shamir, and Adleman. The advantage of this type of encryption is that you can distribute the number "n" and "e" (which make up the encryption key) to everyone. The decryption key "d" is kept secret, so only you and a select few can read the encrypted plaintext. The process by which this is done is that a message, for example "Hello World" is converted to numbers (a=01,b=02,...,z=26). This yields a string of numbers, generally referred to as "numerical plaintext", or "P". For this example, "Hello World" with n = 2537, would be [805, 1212, 1523, 1518, 1204]. The plaintext is split into blocks because no one block can be larger than the value of n, else the decryption will fail. The ciphertext, C, is then computed by taking each block of P, and computing C ≡ P^e mod(n). Similarly, to decode, one computes P ≡ C^d mod(n).