Abstract: There are provided a reflective photomask and a reflective photomask blank having a high contrast of a minute pattern to an inspection light and capable of minimizing the shadowing effect in EUV exposure. A reflective photomask blank (100) of this embodiment includes: a substrate (11); a reflective part (17); and a low reflective part (18), in which the low reflective part (18) is a multi-layer structural body having at least two or more layers including an absorption layer (14) and an outermost layer (15), an extinction coefficient k to a wavelength of 13.5 nm of the absorption layer (14) is k>0.041, and the film thickness of the low reflective part (18) is a film thickness satisfying 0.5×da+dc?21.5 nm or a film thickness satisfying 0.5×da+dc?27.5 nm, wherein the film thickness of the absorption layer (14) is da and the film thickness of the outermost layer (15) is dc.

Abstract: There is provided a reflective photomask blank capable of suppressing or reducing the shadowing effect of a reflective photomask for patterning transfer using a light having a wavelength in the extreme ultraviolet region as a light source and sufficiently having heat resistance in exposure. The reflective photomask blank is configured to have a substrate 1, a reflective layer 2 including a multi-layer film formed on the substrate 1, and an absorption layer 4 formed on the reflective layer 2. The absorption layer 4 contains a total of 50 at % or more of indium (In) and nitrogen (N). The atomic number ratio (N/In) of nitrogen (N) to indium (In) in the absorption layer 4 is set to 0.5 or more and 1.5 or less. The layer thickness of the absorption layer 4 is set to 17 nm or more and 45 nm or less.

Abstract: A non-linear processor, which subjects an input value from a feedback shift register storing an internal state of a stream cipher to non-linear processing to output a key stream, is connected to internal registers, which store output values from a non-linear substitution circuit which subjects the input value to non-linear substitution processing. The non-linear processor is provided with an exclusive-OR unit, which is at an input end of each of the internal registers and carries out an operation of a random number generated from part of values stored in the feedback shift register and the output value of the non-linear substitution circuit to mask the output value of the non-linear substitution circuit, and another exclusive-OR unit, which is provided at an output end of the internal register and performs an operation to unmask the value stored in the internal register.

Abstract: A stream-cipher encrypting method includes first step of expanding an initial key in advance to generate an expanded key by a key expanding unit, a second step of inputting the generated expanded key and an initial value in the initialization processing by an initialization processing unit to carry out the initialization processing, a third step by a key-sequence generating unit of inputting a feedback value from a non-linear unit after the initialization processing is finished, parallelly processing non-linear processing, and maintaining and processing rearranging processing and a multiplication result, which is for obtaining the feedback value, as a data table to generate a key sequence by a non-linear function, and a fourth step of carrying out an exclusive-OR operation of the generated key sequence and a plaintext to generate an encrypted text by an encrypted-text generating unit.

Abstract: A non-linear processor, which subjects an input value from a feedback shift register storing an internal state of a stream cipher to non-linear processing to output a key stream, is connected to internal registers, which store output values from a non-linear substitution circuit which subjects the input value to non-linear substitution processing. The non-linear processor is provided with an exclusive-OR unit, which is at an input end of each of the internal registers and carries out an operation of a random number generated from part of values stored in the feedback shift register and the output value of the non-linear substitution circuit to mask the output value of the non-linear substitution circuit, and another exclusive-OR unit, which is provided at an output end of the internal register and performs an operation to unmask the value stored in the internal register.