Audio frequency camouflage and recovery method that combines secret key with random unit orthogonal basis

The invention discloses an audio frequency camouflage and recovery method that combines a secret key with random unit orthogonal basis; the method comprises the following steps: firstly dividing a secret audio frequency and a public audio frequency into small segment sequences of the same quantity, and using the secret key to build the random unit orthogonal basis; secondarily, solving the projection of the secret audio frequency small segment sequence on the random unit orthogonal basis so as to fully, effectively and linearly express the secret audio frequency small segment sequence, selecting first k projection factors with large amplitude and energy and recording index positions, and thus forming an index sequence; finely adjusting the public audio frequency and using a high capacity built-in secret writing method to embed the selected projection factors and a line sequence into the corresponding public audio frequency small segment sequence, thus forming a channel public transmission audio frequency; usi