nx_rsa2048_mod_exp.nx

nx_rsa2048_mod_exp.nx -- RSA mod-exp s^e mod n for 2048-bit modulus. For RSA-PKCS#1 v1.5 signature verification, the public exponent e is small (commonly 65537 = 2^16 + 1). We implement square-and- multiply MSB-first over the bits of e expressed as an i64 (up to 64-bit exponent supported). For e = 65537 = 0x10001, bits 16 and 0 are set; the loop runs max(bit_length(e)) iterations. API: rsa2048_mod_exp(out, s, e: i64, n) -- out = s^e mod n Caller responsibilities: - s < n (range-checked here; returns nonzero verdict if s >= n) - n is 2048-bit with top bit set - e fits in i64 (true for all Web PKI: e is either 3, 17, 65537) license_tier: INDEPENDENT_REDERIVE genealogy_id: international-research-sources/ietf/rfc_8017 lineage_id: nishi_rsa2048_mod_exp_q10