A method for processing data comprising: receiving a first biometric data and a first personal key; a first processing step for processing the first biometric data and the first personal key through an irreversible cryptographic algorithm to form a first processed data; receiving a second biometric data and a second personal key; a second processing step for processing the second biometric data and the second personal key through the irreversible cryptographic algorithm to form a second processed data; generating a first variant from the first biometric data prior to processing the first biometric data and the first personal key through the irreversible cryptographic algorithm, wherein the first processing step uses the first variant as the first biometric data; generating a second variant from the second biometric data prior to processing the second biometric data and the second personal key through the irreversible cryptographic algorithm, wherein the second processing step uses the second variant as the second biometric data; comparing the second processed data to the first processed data; and generating a signal indicating the result of the comparison of the second processed data to the first processed data, the method being characterized in that it further comprises: processing the first biometric data through a secondary irreversible cryptographic algorithm prior to processing the first biometric data and the first personal key through the irreversible cryptographic algorithm; and processing the second biometric data through the secondary irreversible cryptographic algorithm prior to processing the second biometric data and the second personal key through the irreversible cryptographic algorithm. receiving a first biometric data and a first personal key; a first processing step for processing the first biometric data and the first personal key through an irreversible cryptographic algorithm to form a first processed data; receiving a second biometric data and a second personal key; a second processing step for processing the second biometric data and the second personal key through the irreversible cryptographic algorithm to form a second processed data; generating a first variant from the first biometric data prior to processing the first biometric data and the first personal key through the irreversible cryptographic algorithm, wherein the first processing step uses the first variant as the first biometric data; generating a second variant from the second biometric data prior to processing the second biometric data and the second personal key through the irreversible cryptographic algorithm, wherein the second processing step uses the second variant as the second biometric data; comparing the second processed data to the first processed data; and generating a signal indicating the result of the comparison of the second processed data to the first processed data, the method being characterized in that it further comprises: processing the first biometric data through a secondary irreversible cryptographic algorithm prior to processing the first biometric data and the first personal key through the irreversible cryptographic algorithm; and processing the second biometric data through the secondary irreversible cryptographic algorithm prior to processing the second biometric data and the second personal key through the irreversible cryptographic algorithm. processing the first biometric data through a secondary irreversible cryptographic algorithm prior to processing the first biometric data and the first personal key through the irreversible cryptographic algorithm; and processing the second biometric data through the secondary irreversible cryptographic algorithm prior to processing the second biometric data and the second personal key through the irreversible cryptographic algorithm.