Abstract: Some embodiments are directed to a computer-implemented method (1200) of performing a computation on LWE-encrypted values. The invention relates to the TFHE setting in which the encryption supports a programmable bootstrapping operation that evaluates an LWE decryption in an exponent of a GLWE-encrypted monomial. In this setting, a LWE-encrypted product value is computed based on one or more LWE-encrypted input values by applying a cryptographic key switching operation to convert the LWE-encrypted input values to GLWE-encrypted polynomials, wherein a coefficient of an polynomial is a linear combination of the set of input values; applying an encrypted polynomial multiplication in the GLWE domain, and applying a cryptographic sample extraction operation to the resulting GLWE-encrypted polynomial to obtain the LWE-encrypted product value as an encryption of one of its coefficients.

Abstract: Some embodiments are directed to a computer-implemented method (1200) of performing a computation on LWE-encrypted values. The invention relates to the TFHE setting in which the encryption supports a programmable bootstrapping operation that evaluates an LWE decryption in an exponent of a GLWE-encrypted monomial. In this setting, a LWE-encrypted product value is computed based on one or more LWE-encrypted input values by applying a cryptographic key switching operation to convert the LWE-encrypted input values to GLWE-encrypted polynomials, wherein a coefficient of an polynomial is a linear combination of the set of input values; applying an encrypted polynomial multiplication in the GLWE domain, and applying a cryptographic sample extraction operation to the resulting GLWE-encrypted polynomial to obtain the LWE-encrypted product value as an encryption of one of its coefficients.