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+/*
+ * Copyright (c) 2017 Cisco and/or its affiliates.
+ * 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.
+ */
+
+/**
+ * @file parc_Base64.h
+ * @ingroup inputoutput
+ * @brief Encode/decode base64
+ *
+ * Encoding goes to one long line, no line breaks.
+ * Decoding will accept CRLF linebreaks in the data and skip them.
+ *
+ * Following the language of RFC 4648, encoding proceeds in a "quantum" of
+ * 3 bytes of plaintext to 4 bytes of encoded data.  Decoding goes in
+ * a 4-byte quantum to 3-byte decoded data.
+ *
+ * If decoding fails (e.g. there's a non-base64 character), then the output
+ * buffer is rewound to the starting position and a failure is indicated.
+ *
+ * Decoding using a 256 byte table.  Each byte of the 4-byte quantum is looked
+ * up and if its a valid character -- it resolves to a value 0..63, then that
+ * value is shifted to the right position in the output.  Values CR and LF have
+ * the special token "_" in the table, which means "skip".  That token has value
+ * ascii value 95, is we can detect it as outside base64.  Similarly, all the
+ * invalid characters have the symbol "~", which is ascii 127.
+ *
+ */
+#ifndef libparc_parc_Base64_h
+#define libparc_parc_Base64_h
+
+#include <parc/algol/parc_Buffer.h>
+#include <parc/algol/parc_BufferComposer.h>
+
+/**
+ * Encode the plaintext buffer to base64, as per RFC 4648, Section 4.
+ *
+ * The base64 encoding is appended to `output` at the current position, and `output` is returned.
+ *
+ * @param [in,out] output The instance of {@link PARCBufferComposer} to which the encoded @plainText is appended
+ * @param [in] plainText The text to encode and append to @p output
+ *
+ * @return  A pointer to the @p output
+ *
+ * Example:
+ * @code
+ * {
+ *     <#example#>
+ * }
+ * @endcode
+ *
+ */
+PARCBufferComposer *parcBase64_Encode(PARCBufferComposer *output, PARCBuffer *plainText);
+
+/**
+ * Encode the array to base64.
+ *
+ * @param [in,out] output The instance of {@link PARCBufferComposer} to which the encoded @p array is appended
+ * @param [in] length The length of the Array to be encoded
+ * @param array The array to be encoded and appended to @p output
+ *
+ * @return  A pointer to the @p output
+ *
+ * Example:
+ * @code
+ * <#example#>
+ * @endcode
+ */
+PARCBufferComposer *parcBase64_EncodeArray(PARCBufferComposer *output, size_t length, const uint8_t *array);
+
+/**
+ * Base64 decode the @p encodedText and append the result to @p output,
+ * which is returned by the function.
+ *
+ * If the @p encodedText cannot be base64 decoded,
+ * @p output is reset to the starting position and the function returns NULL.
+ *
+ * @param [in,out] output The instance of {@link PARCBufferComposer} to which the decoded @p encodedText is appended
+ * @param [in] encodedText The array to be decoded and appended to @p output
+ *
+ * @return  A pointer to the @p output, or NULL if the @p encodedText cannot be base64 decoded
+ *
+ * Example:
+ * @code
+ * <#example#>
+ * @endcode
+ */
+PARCBufferComposer *parcBase64_Decode(PARCBufferComposer *output, PARCBuffer *encodedText);
+
+/**
+ * Base64 decode the string, using strlen() to get the length.
+ *
+ * @param [in,out] output The instance of {@link PARCBufferComposer} to which the decoded @p encodedText is appended
+ * @param [in] encodedString The string to be decoded and appended to @p output
+ *
+ * @return  A pointer to the @p output, or NULL if the @p encodedString cannot be base64 decoded
+ * Example:
+ * @code
+ * <#example#>
+ * @endcode
+ */
+PARCBufferComposer *parcBase64_DecodeString(PARCBufferComposer *output, const char *encodedString);
+
+/**
+ * Base64 decode the array.
+ *
+ * @param [in,out] output The instance of {@link PARCBufferComposer} to which the decoded @p array is appended
+ * @param [in] length The size of the array.
+ * @param [in] array The array to be decoded and appended to @p output
+ *
+ * @return  A pointer to the @p output, or NULL if the @p encodedString cannot be base64 decoded
+ *
+ * Example:
+ * @code
+ * <#example#>
+ * @endcode
+ */
+PARCBufferComposer *parcBase64_DecodeArray(PARCBufferComposer *output, size_t length, const uint8_t *array);
+#endif // libparc_parc_Base64_h