Multi-biometric systems have several advantages over uni-biometrics based systems, such as, better verification accuracy, larger feature space to accommodate more subjects, and higher security against spoofing. Unfortunately, as in case of uni-biometric systems, multi-biometric systems also face the problems of nonrevocability, lack of template diversity, and possibility of privacy compromise. A combination of biometrics and cryptography is a good solution eliminate these limitations. In this chapter we present a multi-biometric cryptosystem based on the fuzzy commitment scheme, in which, a crypto-biometric key is derived from multi-biometric data. An idea (recently proposed by the authors) denoted as FeaLingECc (Feature Level Fusion through Weighted Error Correction) is used for the multi-biometric fusion. The FeaLingECc allows fusion of different biometric modalities having variation in performances (e.g., face+iris). This scheme is adapted for a multi-unit system based on two-irises and a multi-modal system using a combination of iris and face. The difficulty in obtaining the crypto-biometric key locked in the system (and in turn the reference biometric data) is 189 bits for the two-iris system while 183 bits for the iris-face system using brute force attack. In addition to the strong keys, these systems possess revocability and template diversity and protect user privacy.