include/mbedtls/base64.h

/**
 * \file base64.h
 *
 * \brief RFC 1521 base64 encoding/decoding
 */
/*
 *  Copyright The Mbed TLS Contributors
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
 *  not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
#ifndef MBEDTLS_BASE64_H
#define MBEDTLS_BASE64_H

#include "mbedtls/build_info.h"

#include <stddef.h>

/** Output buffer too small. */
#define MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL               -0x002A
/** Invalid character in input. */
#define MBEDTLS_ERR_BASE64_INVALID_CHARACTER              -0x002C

#ifdef __cplusplus
extern "C" {
#endif

/**
 * \brief          Encode a buffer into base64 format
 *
 * \param dst      destination buffer
 * \param dlen     size of the destination buffer
 * \param olen     number of bytes written
 * \param src      source buffer
 * \param slen     amount of data to be encoded
 *
 * \return         0 if successful, or MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL.
 *                 *olen is always updated to reflect the amount
 *                 of data that has (or would have) been written.
 *                 If that length cannot be represented, then no data is
 *                 written to the buffer and *olen is set to the maximum
 *                 length representable as a size_t.
 *
 * \note           Call this function with dlen = 0 to obtain the
 *                 required buffer size in *olen
 */
int mbedtls_base64_encode(unsigned char *dst, size_t dlen, size_t *olen,
                          const unsigned char *src, size_t slen);

/**
 * \brief          Decode a base64-formatted buffer
 *
 * \param dst      destination buffer (can be NULL for checking size)
 * \param dlen     size of the destination buffer
 * \param olen     number of bytes written
 * \param src      source buffer
 * \param slen     amount of data to be decoded
 *
 * \return         0 if successful, MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL, or
 *                 MBEDTLS_ERR_BASE64_INVALID_CHARACTER if the input data is
 *                 not correct. *olen is always updated to reflect the amount
 *                 of data that has (or would have) been written.
 *
 * \note           Call this function with *dst = NULL or dlen = 0 to obtain
 *                 the required buffer size in *olen
 */
int mbedtls_base64_decode(unsigned char *dst, size_t dlen, size_t *olen,
                          const unsigned char *src, size_t slen);

#if defined(MBEDTLS_SELF_TEST)
/**
 * \brief          Checkup routine
 *
 * \return         0 if successful, or 1 if the test failed
 */
int mbedtls_base64_self_test(int verbose);

#endif /* MBEDTLS_SELF_TEST */

#if defined(MBEDTLS_TEST_HOOKS)

/** Given a value in the range 0..63, return the corresponding Base64 digit.
 *
 * The implementation assumes that letters are consecutive (e.g. ASCII
 * but not EBCDIC).
 *
 * \param value     A value in the range 0..63.
 *
 * \return          A base64 digit converted from \p value.
 */
unsigned char mbedtls_ct_base64_enc_char(unsigned char value);

/** Given a Base64 digit, return its value.
 *
 * If c is not a Base64 digit ('A'..'Z', 'a'..'z', '0'..'9', '+' or '/'),
 * return -1.
 *
 * The implementation assumes that letters are consecutive (e.g. ASCII
 * but not EBCDIC).
 *
 * \param c     A base64 digit.
 *
 * \return      The value of the base64 digit \p c.
 */
signed char mbedtls_ct_base64_dec_value(unsigned char c);

#endif /* MBEDTLS_TEST_HOOKS */

#ifdef __cplusplus
}
#endif

#endif /* base64.h */