As a result of the growing interest in biometrics a new field of research has emerged entitled Biometric Cryptosystems. Only a small amount of work, which additionally tends to be custom-built according to the specific application context, has been published in this area. This work provides a systematic treatment of how to construct biometric cryptosystems based on iris biometrics. A cryptographic primitive called Fuzzy Commitment Scheme is adopted to different types of iris recognition algorithms to hide and retrieve a cryptographic key in and out of a biometric template. Experimental results confirm the soundness of the approach.