Source
pub fn parseDer(pub_key: []const u8) ParseDerError!struct { modulus: []const u8, exponent: []const u8 } {
const pub_key_seq = try der.Element.parse(pub_key, 0);
if (pub_key_seq.identifier.tag != .sequence) return error.CertificateFieldHasWrongDataType;
const modulus_elem = try der.Element.parse(pub_key, pub_key_seq.slice.start);
if (modulus_elem.identifier.tag != .integer) return error.CertificateFieldHasWrongDataType;
const exponent_elem = try der.Element.parse(pub_key, modulus_elem.slice.end);
if (exponent_elem.identifier.tag != .integer) return error.CertificateFieldHasWrongDataType;
// Skip over meaningless zeroes in the modulus.
const modulus_raw = pub_key[modulus_elem.slice.start..modulus_elem.slice.end];
const modulus_offset = for (modulus_raw, 0..) |byte, i| {
if (byte != 0) break i;
} else modulus_raw.len;
return .{
.modulus = modulus_raw[modulus_offset..],
.exponent = pub_key[exponent_elem.slice.start..exponent_elem.slice.end],
};
}