Speak Freely for Windows

IDEA encryption

If an IDEA key is specified in the Option/Connections... dialogue, it will be is used to encrypt sound transmitted to that host with the International Data Encryption Algorithm (IDEA). In order to decrypt sound encoded with IDEA, the connection on the receiving machine specify an identical IDEA key. The IDEA key phrase can be as long as 255 characters. The actual IDEA key is created by applying the MD5 algorithm to the given key phrase to create the 128 bit IDEA key.

IDEA encryption is substantially faster and generally considered to be much more secure than DES encryption. However, IDEA is newer, has not been formally adopted by governments, and is patented, restricting its commercial use. If your CPU is fast enough, you can enable any combination of IDEA, DES, and key file encryption. But since PGP uses IDEA to transmit message bodies, if you rely on PGP to exchange keys with other parties, the fundamental security of your voice link rests upon IDEA alone.

Cipher block chaining is used within each sound packet, but not from packet to packet. If that were done, loss of a single packet would render the entire rest of the conversation unintelligible.

Speak Freely will continue to correctly receive unencrypted sound from a given host even if an IDEA key is specified for the connection.

The IDEA encryption algorithm is patented and may not be used commercially without a license; see "Patent issues" for further details.