-with either key and only the counterpart of that key can decrypt
-the message. While RSA can be used for both signing and encrypting
-a message, paraslash uses RSA only for the latter purpose. The
-RSA public key encryption and signatures algorithms are defined in
-detail in RFC 2437.
-
-RC4 is a stream cipher, i.e. the input is XORed with a pseudo-random
-key stream to produce the output. Decryption uses the same function
-calls as encryption. While RC4 supports variable key lengths,
-paraslash uses a fixed length of 256 bits, which is considered a
-strong encryption by today's standards. Since the same key must never
-be used twice, a different, randomly-generated key is used for every
-new connection.
+with either key and only the counterpart of that key can decrypt the
+message. Asymmetric block ciphers can be used for both signing and
+encrypting a message.
+
+RSA is an asymmetric block cipher which is used in many applications,
+including ssh and gpg. The RSA public key encryption and signatures
+algorithms are defined in detail in RFC 2437. Paraslash relies on
+RSA for authentication.
+
+Stream ciphers XOR the input with a pseudo-random key stream to produce
+the output. Decryption uses the same function calls as encryption.
+Any block cipher can be turned into a stream cipher by generating the
+pseudo-random key stream by encrypting successive values of a counter
+(counter mode).