[linux.git] / lib / base64.c

// SPDX-License-Identifier: GPL-2.0
/*
 * base64.c - RFC4648-compliant base64 encoding
 *
 * Copyright (c) 2020 Hannes Reinecke, SUSE
 *
 * Based on the base64url routines from fs/crypto/fname.c
 * (which are using the URL-safe base64 encoding),
 * modified to use the standard coding table from RFC4648 section 4.
 */

#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/export.h>
#include <linux/string.h>
#include <linux/base64.h>

static const char base64_table[65] =
	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

/**
 * base64_encode() - base64-encode some binary data
 * @src: the binary data to encode
 * @srclen: the length of @src in bytes
 * @dst: (output) the base64-encoded string.  Not NUL-terminated.
 *
 * Encodes data using base64 encoding, i.e. the "Base 64 Encoding" specified
 * by RFC 4648, including the  '='-padding.
 *
 * Return: the length of the resulting base64-encoded string in bytes.
 */
int base64_encode(const u8 *src, int srclen, char *dst)
{
	u32 ac = 0;
	int bits = 0;
	int i;
	char *cp = dst;

	for (i = 0; i < srclen; i++) {
		ac = (ac << 8) | src[i];
		bits += 8;
		do {
			bits -= 6;
			*cp++ = base64_table[(ac >> bits) & 0x3f];
		} while (bits >= 6);
	}
	if (bits) {
		*cp++ = base64_table[(ac << (6 - bits)) & 0x3f];
		bits -= 6;
	}
	while (bits < 0) {
		*cp++ = '=';
		bits += 2;
	}
	return cp - dst;
}
EXPORT_SYMBOL_GPL(base64_encode);

/**
 * base64_decode() - base64-decode a string
 * @src: the string to decode.  Doesn't need to be NUL-terminated.
 * @srclen: the length of @src in bytes
 * @dst: (output) the decoded binary data
 *
 * Decodes a string using base64 encoding, i.e. the "Base 64 Encoding"
 * specified by RFC 4648, including the  '='-padding.
 *
 * This implementation hasn't been optimized for performance.
 *
 * Return: the length of the resulting decoded binary data in bytes,
 *	   or -1 if the string isn't a valid base64 string.
 */
int base64_decode(const char *src, int srclen, u8 *dst)
{
	u32 ac = 0;
	int bits = 0;
	int i;
	u8 *bp = dst;

	for (i = 0; i < srclen; i++) {
		const char *p = strchr(base64_table, src[i]);

		if (src[i] == '=') {
			ac = (ac << 6);
			bits += 6;
			if (bits >= 8)
				bits -= 8;
			continue;
		}
		if (p == NULL || src[i] == 0)
			return -1;
		ac = (ac << 6) | (p - base64_table);
		bits += 6;
		if (bits >= 8) {
			bits -= 8;
			*bp++ = (u8)(ac >> bits);
		}
	}
	if (ac & ((1 << bits) - 1))
		return -1;
	return bp - dst;
}
EXPORT_SYMBOL_GPL(base64_decode);
Commit	Line	Data
a116e1cd HR	1	// SPDX-License-Identifier: GPL-2.0
	2	/*
	3	* base64.c - RFC4648-compliant base64 encoding
	4	*
	5	* Copyright (c) 2020 Hannes Reinecke, SUSE
	6	*
	7	* Based on the base64url routines from fs/crypto/fname.c
	8	* (which are using the URL-safe base64 encoding),
	9	* modified to use the standard coding table from RFC4648 section 4.
	10	*/
	11
	12	#include <linux/kernel.h>
	13	#include <linux/types.h>
	14	#include <linux/export.h>
	15	#include <linux/string.h>
	16	#include <linux/base64.h>
	17
	18	static const char base64_table[65] =
	19	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
	20
	21	/**
	22	* base64_encode() - base64-encode some binary data
	23	* @src: the binary data to encode
	24	* @srclen: the length of @src in bytes
	25	* @dst: (output) the base64-encoded string. Not NUL-terminated.
	26	*
	27	* Encodes data using base64 encoding, i.e. the "Base 64 Encoding" specified
	28	* by RFC 4648, including the '='-padding.
	29	*
	30	* Return: the length of the resulting base64-encoded string in bytes.
	31	*/
	32	int base64_encode(const u8 src, int srclen, char dst)
	33	{
	34	u32 ac = 0;
	35	int bits = 0;
	36	int i;
	37	char *cp = dst;
	38
	39	for (i = 0; i < srclen; i++) {
	40	ac = (ac << 8) \| src[i];
	41	bits += 8;
	42	do {
	43	bits -= 6;
	44	*cp++ = base64_table[(ac >> bits) & 0x3f];
	45	} while (bits >= 6);
	46	}
	47	if (bits) {
	48	*cp++ = base64_table[(ac << (6 - bits)) & 0x3f];
	49	bits -= 6;
	50	}
	51	while (bits < 0) {
	52	*cp++ = '=';
	53	bits += 2;
	54	}
	55	return cp - dst;
	56	}
	57	EXPORT_SYMBOL_GPL(base64_encode);
	58
	59	/**
	60	* base64_decode() - base64-decode a string
	61	* @src: the string to decode. Doesn't need to be NUL-terminated.
	62	* @srclen: the length of @src in bytes
	63	* @dst: (output) the decoded binary data
	64	*
65	* Decodes a string using base64 encoding, i.e. the "Base 64 Encoding"
66	* specified by RFC 4648, including the '='-padding.
67	*
68	* This implementation hasn't been optimized for performance.
69	*
70	* Return: the length of the resulting decoded binary data in bytes,
71	* or -1 if the string isn't a valid base64 string.
72	*/
73	int base64_decode(const char src, int srclen, u8 dst)
74	{
75	u32 ac = 0;
76	int bits = 0;
77	int i;
78	u8 *bp = dst;
79
80	for (i = 0; i < srclen; i++) {
81	const char *p = strchr(base64_table, src[i]);
82
83	if (src[i] == '=') {
84	ac = (ac << 6);
85	bits += 6;
86	if (bits >= 8)
87	bits -= 8;
88	continue;
89	}
90	if (p == NULL \|\| src[i] == 0)
91	return -1;
92	ac = (ac << 6) \| (p - base64_table);
93	bits += 6;
94	if (bits >= 8) {
95	bits -= 8;
96	*bp++ = (u8)(ac >> bits);
97	}
98	}
99	if (ac & ((1 << bits) - 1))
100	return -1;
101	return bp - dst;
102	}
103	EXPORT_SYMBOL_GPL(base64_decode);