Like most free software, Speak Freely exists in large part because I was able to stand on the shoulders of other authors of generally available software. The following software components, either incorporated into Speak Freely or providing a model for how to develop similar software, tremendously reduced the blood, sweat, toil, and tears, not to mention man-months required to complete this software. Any restrictions on the use and distribution of these software components are noted below.
The GSM compression and decompression code was developed by Jutta Degener and Carsten Bormann of the Communications and Operating Systems Research Group, Technische Universität Berlin: Fax: +49.30.31425156, Phone: +49.30.31424315. They note that THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE. Please see the README and COPYRITE files in the gsm directory of the source code distribution for further details.
The ADPCM compression and decompression code was developed by Jack Jansen of the Centre for Mathematics and Computer Science, Amsterdam, The Netherlands. Please see the README and COPYRITE files in the adpcm directory of the source code distribution for further details.
The DES encryption code used with Speak Freely protocol was developed by Phil Karn, KA9Q. Please see the README file in the des directory of the source code distribution for further details.
The DES encryption library used for encrypting and decrypting VAT and RTP protocol packets was developed by Eric Young. Please see the README and COPYRITE files in the libdes directory of the source code distribution for further details.
The Blowfish encryption library was also developed by Eric Young. Please see the README and COPYRITE files in the blowfish directory of the source code distribution for further details. The Blowfish algorithm was invented by Bruce Schneier and placed by him into the public domain.
The IDEA algorithm was developed by Xuejia Lai and James L. Massey, of ETH Zürich. The implementation used in Speak Freely was modified and derived from original C code developed by Xuejia Lai and optimized for speed by Colin Plumb. The IDEA encryption algorithm is patented and may not be used commercially without a license; see "Patent issues" for further details.
The public domain implementation of the Advanced Encryption System (AES) was developed by Brian Gladman. For details, please visit his Web page.
The MD5 message-digest algorithm implementation is based on a public domain version written by Colin Plumb in 1993. The algorithm is due to Ron Rivest.
The experimental Linear Predictive Coding (LPC) compression code was developed by Ron Frederick of Xerox PARC.
The public domain implementation of U.S. Federal Standard 1015 LPC-10 compression algorithm was developed by the United States Department of Defense, National Security Agency (NSA). Please see the README and FAQ files in the lpc10 directory of the source code distribution for additional details.
The U.S. Federal Standard 1016 CELP code-excited linear prediction algorithm and software were developed by Joseph P. Campbell Jr., Vanoy C. Welch and Thomas E. Tremain of the U.S. Department of Defense. Craig F. Reese of the IDA/Supercomputing Research Center adapted the original implementation for use on general-purpose computers. Please see the COVERLETTER and README files in the celp directory of the source code distribution for additional details.
The Voice Activation code, remote Break-in feature, the ability to open additional connections by clicking .SFX files while Speak Freely is already running, and a work-around for Speak Freely hanging the machine when the user has selected compression and encryption modes which overload the CPU were contributed by Dave Hawkes, who also discovered an elegant way to get Windows to do most of the work in jitter compensation.
The initial 32-bit version of Speak Freely for Windows was created by Aleksander Nemirovsky.