---
-- OpenSSL bindings.
--
-- This module is a wrapper for OpenSSL functions that provide encryption and
-- decryption, hashing, and multiprecision integers.
--
-- The <code>openssl</code> module may not always be available. It depends on
-- whether OpenSSL support was enabled at compile time. Scripts using the
-- module should be made to fail gracefully using code like the following:
-- <code>
-- if not pcall(require, "openssl") then
--   action = function(host, port)
--     stdnse.debug2("Skipping \"%s\" because OpenSSL is missing.", id)
--   end
-- end
-- action = action or function(host, port)
--   ...
-- end
-- </code>
-- @author Sven Klemm <sven@c3d2.de>
-- @copyright Same as Nmap--See https://nmap.org/book/man-legal.html

module "openssl"

--- Returns the size of <code>bignum</code> in bits.
-- @param bignum bignum to operate on.
-- @return Size of <code>bignum</code>.
function bignum_num_bits(bignum)

--- Returns the size of <code>bignum</code> in bytes.
-- @param bignum bignum to operate on.
-- @return Size of <code>bignum</code>.
function bignum_num_bytes(bignum)

--- Sets the bit at <code>position</code> in <code>bignum</code>.
-- @param bignum bignum to operate on.
-- @param position Bit position.
function bignum_set_bit(bignum, position)

--- Clears the bit at <code>position</code> in <code>bignum</code>.
-- @param bignum bignum to operate on.
-- @param position Bit position.
function bignum_clear_bit(bignum, position)

--- Gets the state of the bit at <code>position</code> in <code>bignum</code>.
-- @param bignum bignum to operate on.
-- @param position Bit position.
-- @return True if the selected bit is set, false otherwise.
function bignum_is_bit_set(bignum, position)

--- Checks whether <code>bignum</code> is probably prime.
--
-- Performs Miller-Rabin probabilistic primality tests.
-- @param bignum bignum to check for primality
-- @param nchecks Number of checks to perform. Default: number of checks dependent on bitsize of bignum, with a false positive rate of at most 2^-80
-- @return True if the number is probably prime, false if it is composite.
function bignum_is_prime(bignum, nchecks)

--- Checks whether <code>bignum</code> is a safe prime.
--
-- A safe prime is defined as a prime p so that (p-1)/2 is also prime. Using
-- non-safe primes in discrete logarithm cryptography like Diffie-Hellman can
-- result in weak, easily broken key exchanges.
-- @param bignum bignum to check for primality
-- @param nchecks Number of checks to perform. Default: number of checks dependent on bitsize of bignum, with a false positive rate of at most 2^-80
-- @return True if the number is a safe prime, false if it is not.
-- @return True if the number is probably prime, false if it is composite.
function bignum_is_safe_prime(bignum, nchecks)

--- Converts a binary-encoded string into a bignum.
-- @param string Binary string.
-- @return bignum.
function bignum_bin2bn(string)

--- Converts a decimal-encoded string into a bignum.
-- @param string Decimal string.
-- @return bignum.
function bignum_dec2bn(string)

--- Converts a hex-encoded string into a bignum.
-- @param string Hex string.
-- @return bignum.
function bignum_hex2bn(string)

--- Converts <code>bignum</code> into a binary-encoded string.
-- @param bignum bignum to operate on.
-- @return Binary string.
function bignum_bn2bin(bignum)

--- Converts <code>bignum</code> into a decimal-encoded string.
-- @param bignum bignum to operate on.
-- @return Decimal string.
function bignum_bn2dec(bignum)

--- Converts <code>bignum</code> into a hex-encoded string.
-- @param bignum bignum to operate on.
-- @return Hex string.
function bignum_bn2hex(bignum)

--- Returns a random bignum.
-- @param bits Size of the returned bignum in bits.
-- @return Random bignum.
function bignum_rand(bits)

--- Returns a pseudorandom bignum.
-- @param bits Size of the returned bignum in bits.
-- @return Pseudorandom bignum.
function bignum_pseudo_rand(bits)

--- Returns the bignum which is the result of <code>a</code>^<code>p</code> mod
-- <code>m</code>.
-- @param a Base.
-- @param p Exponent.
-- @param m Modulus.
-- @return bignum.
function bignum_mod_exp(a, p, m)

--- Returns the bignums which are the result and remainder of <code>a/b</code>
-- @param a bignum
-- @param b bignum
-- @return bignum quotient
-- @return bignum remainder (modulo)
function bignum_div(a, b)

--- Returns the bignum which is the result of <code>a+b</code>
-- @param a bignum
-- @param b bignum
-- @return bignum
function bignum_add(a, b)

--- Returns a string containing cryptographically-strong random data.
--
-- If the PRNG has not been seeded with enough randomness, this function throws an error.
-- @param bytes Length of the returned string in bytes.
-- @return Random string.
function rand_bytes(bytes)

--- Returns a string containing pseudorandom data.
--
-- No indication is given whether or not the contents of the string are
-- cryptographically strong.
-- @param bytes Length of the returned string in bytes.
-- @return Pseudorandom string.
function rand_pseudo_bytes(bytes)

--- Returns the MD4 digest of a string.
-- @param message String to digest.
-- @return MD4 digest.
function md4(message)

--- Returns the MD5 digest of a string.
-- @param message String to digest.
-- @return MD5 digest.
function md5(message)

--- Returns the SHA-1 digest of a string.
-- @param message String to digest.
-- @return SHA-1 digest.
function sha1(message)

--- Returns the RIPEMD-160 digest of a string.
-- @param message String to digest.
-- @return RIPEMD-160 digest.
function ripemd160(message)

--- Returns the digest of a string using a named algorithm.
-- @param algorithm Any of the strings returned by
-- <code>openssl.supported_digests</code>.
-- @param message String to digest.
function digest(algorithm, message)

--- Returns the message authentication code of a string using a named algorithm.
-- @param algorithm Any of the strings returned by
-- <code>openssl.supported_digests</code>.
-- @param key Key.
-- @param message String.
function hmac(algorithm, key, message)

--- Encrypt data with a given algorithm, key, and initialization vector.
-- @param algorithm Any of the strings returned by
-- <code>openssl.supported_ciphers</code>.
-- @param key Key.
-- @param iv Initialization vector.
-- @param data Data to encrypt.
-- @param padding If true, then a partial final block will be padded and
-- encrypted (default false).
function encrypt(algorithm, key, iv, data, padding)

--- Decrypt data with a given algorithm, key, and initialization vector.
-- @param algorithm Any of the strings returned by
-- <code>openssl.supported_ciphers</code>.
-- @param key Key.
-- @param iv Initialization vector.
-- @param data Data to decrypt.
-- @param padding If true, then the final block must be padded correctly
-- (default false).
function decrypt(algorithm, key, iv, data, padding)

--- Returns a table with the names of the supported cipher algorithms.
-- @return Array containing cipher names as strings.
function supported_ciphers()

--- Returns a table with the names of the supported digest algorithms.
-- @return Array containing digest names as strings.
function supported_digests()

--- Converts a 56-bit DES key into a 64-bit key with the correct parity.
-- @param data A 7-byte string.
-- @return An 8-byte string.
function DES_string_to_key(data)

--- Returns options for RC4.
-- @return Option string.
function rc4_options()

--- Function which generates an RC4 cipher function with the given key.
-- @param key_data The key for the cipher.
-- @return A function which performs the RC4 stream cipher on an input string and returns the result.
function rc4(key_data)
