nx_argon2_block_test.nx

nx_argon2_block_test.nx -- algebraic-property smoke for G(X, Y). expect_exit: 0 Tests: 1. G(0, 0) = 0 -- all-zero in, all-zero out (R = 0 XOR 0 = 0; GB(0,0,0,0) = (0,0,0,0); final XOR yields 0). 2. G(X, X) = 0 -- self-XOR makes R = 0; same as test 1. 3. G(X, Y) symmetric: G(X, Y) == G(Y, X). R = X XOR Y is symmetric, P operates on R, final XOR R is symmetric. 4. G(X, Y) deterministic: two runs yield same output. 5. G(X, Y) sensitive to a single-bit flip in X (avalanche check): flipping one bit of X must change at least 256 bits of output (4x SHA-256-style avalanche; Argon2's G empirically has very strong avalanche due to multiplications). license_tier: ORIGINAL