crypto_mod_exp() function

crypto_mod_exp - Modular exponentiation of large integers @base: Base integer (big endian byte array) @base_len: Length of base integer in bytes @power: Power integer (big endian byte array) @power_len: Length of power integer in bytes @modulus: Modulus integer (big endian byte array) @modulus_len: Length of modulus integer in bytes @result: Buffer for the result @result_len: Result length (max buffer size on input, real len on output) Returns: 0 on success, -1 on failure This function calculates result = base ^ power mod modulus. modules_len is used as the maximum size of modulus buffer. It is set to the used size on success. This function is only used with internal TLSv1 implementation (CONFIG_TLS=internal). If that is not used, the crypto wrapper does not need to implement this.