This document proposes an adaptive steganography technique for hiding secret data in digital images. The technique uses variable bit length embedding based on wavelet coefficients of the cover image. A logistic map is used to generate a secret key, which determines the RGB color planes and blocks used for data hiding. Wavelet coefficients are classified into ranges, and the number of bits hidden corresponds to the coefficient value range. Extraction involves selecting the same coefficients based on the key and calculating the hidden bits. The technique aims to improve security, capacity and imperceptibility compared to existing constant bit length methods. Evaluation shows the proposed method provides good security since variable bits are hidden randomly using the secret key.