encryption

Encryption is the technique of transforming a value by means of a cipher in order to order to conceal its meaning.

See Also

cipher
Everything related to ciphers themselves.
hash functions
Cryptkit
A Tcl binding to the well-known Cryptlib cryptography toolkit.
PGP
tls
SSL
Huffman coding, part 2
A step towards compressing encryption, if you don't transmit the map.
Molebox encrypted Windows exe
NaCl - Networking and Cryptography library (pronounced "salt")
tcllib
Includes pure-Tcl implementations of the des, aes, blowfish and rc4 ciphers. It also has implementations of the md4, md5, sha1, sha2 and ripemd message digest algorithms.
Tcl binding to libmcrypt.
Tcl binding to SEED encryption library.
CryptoVe
Tcl binding to MIRACL (Multiprecision Integer and Rational Arithmetic C Library) library. MIRACL is self-described as "a C software library that is widely regarded by developers as the gold standard open source SDK for elliptic curve cryptography".

Description

Protocols like SSH and SSL work by using an asymmetric cipher to establish a symmetric key, and then using the symmetric key, which is more performant, for the remainer of the session.