Patent ID: 8165289

Claim:
An encryption and decryption method comprising configuring at least one processor to perform the functions of: generating a code from a set of biometric samples, each sample in the form of a pattern, the code generating comprising: analysing a plurality of samples and obtaining feature values for the samples, each sample being interpreted as a plurality of features of a previously defined feature set obtained during an initial calibration; normalising the feature values by adapting the feature values such that they may each take only a predetermined range of values, each with substantially equal likelihood; obtaining mean, variance and covariance values for the different feature values from the plurality of samples; setting quantization levels for each feature using the obtained mean and variance values, the quantization levels determining the range of feature values to be considered as equivalent; de-correlating the feature values using de-correlating coefficients obtained from the covariance values; and deriving a single code from a combination of the de-correlated feature values, wherein the single code comprises a sub-set of the bits derived from the combination of feature values; using the code to form a private encryption key; using the private encryption key to encrypt data; decrypting the encrypted data by taking a further biometric sample to generate the required private key, wherein the method is template-free having no physical record of the private key or any form of information regarding the biometric itself; wherein the initial calibration phase for determining said previously defined feature set comprises: obtaining multiple calibration samples from multiple users; analysing the calibration samples and obtaining feature values for the samples; and obtaining mean, variance, and covariance values for the different features from the plurality of samples, wherein those mean and variance values are used in setting static quantization intervals used to re-create each time dynamically said mean and variance values of said code generating phase.