Resumen
This article reports that digital multimedia is exposed to a broad spectrum of security problems. From the standpoint of the media provider, protection of materials from unauthorized distribution or modification is a primary concern. At the delivery end, recipients want to ensure that downloads are virus-free and legitimately obtained. Ironically, encryption and digital branding tools can be employed both for securing multimedia as well as for circumventing laws pertaining to content and use. The most popular of these techniques are steganography and watermarking or the addition of an unremovable identifier to tag the content, indicating ownership. One popular method used for data encoding in digital audio files is Least Significant Bit, where the low bit of each sound sample is successively replaced by digits from a binary string. Another is phase coding, where the phase of an audio signal is replaced by a reference phase used to modulate a data signal. Echoes can even be altered in order to conceal information. All these techniques rely on the fact that the perception of sound is rather inaccurate.