base64 encoder/decoder for objective-c编码及解码，转

base64是广为使用的一种编码及解码方式， 通常用于网络传输和邮件传输中，使用base64可以将标点符号以及多字节文字等特殊字符编码以便传输，以下是base64 编码解码的objective－c代码， 可以用于desktop和iphone程序当中.

/* base64.h */

extern size_t EstimateBas64EncodedDataSize(size_t inDataSize);

extern size_t EstimateBas64DecodedDataSize(size_t inDataSize);

extern bool Base64EncodeData(const void *inInputData, size_t inInputDataSize, char *, size_t *ioOutputDataSize, BOOL wrapped);

extern bool Base64DecodeData(const void *inInputData, size_t , void *ioOutputData, size_t *ioOutputDataSize);

/* base64.m*/

#include "base64.h"

#include <math.h>

const UInt8 kBase64EncodeTable[64] = {

/* 0 */ 'A', /* 1 */ 'B', /* 2 */ 'C', /* 3 */ 'D',

/* 4 */ 'E', /* 5 */ 'F', /* 6 */ 'G', /* 7 */ 'H',

/* 8 */ 'I', /* 9 */ 'J', /* 10 */ 'K', /* 11 */ 'L',

/* 12 */ 'M', /* 13 */ 'N', /* 14 */ 'O', /* 15 */ 'P',

/* 16 */ 'Q', /* 17 */ 'R', /* 18 */ 'S', /* 19 */ 'T',

/* 20 */ 'U', /* 21 */ 'V', /* 22 */ 'W', /* 23 */ 'X',

/* 24 */ 'Y', /* 25 */ 'Z', /* 26 */ 'a', /* 27 */ 'b',

/* 28 */ 'c', /* 29 */ 'd', /* 30 */ 'e', /* 31 */ 'f',

/* 32 */ 'g', /* 33 */ 'h', /* 34 */ 'i', /* 35 */ 'j',

/* 36 */ 'k', /* 37 */ 'l', /* 38 */ 'm', /* 39 */ 'n',

/* 40 */ 'o', /* 41 */ 'p', /* 42 */ 'q', /* 43 */ 'r',

/* 44 */ 's', /* 45 */ 't', /* 46 */ 'u', /* 47 */ 'v',

/* 48 */ 'w', /* 49 */ 'x', /* 50 */ 'y', /* 51 */ 'z',

/* 52 */ '0', /* 53 */ '1', /* 54 */ '2', /* 55 */ '3',

/* 56 */ '4', /* 57 */ '5', /* 58 */ '6', /* 59 */ '7',

/* 60 */ '8', /* 61 */ '9', /* 62 */ '+', /* 63 */ '/'

};

/*

-1 = Base64 end of data marker.

-2 = White space (tabs, cr, lf, space)

-3 = Noise (all non whitespace, non-base64 characters)

-4 = Dangerous noise

-5 = Illegal noise (null byte)

*/

const SInt8 kBase64DecodeTable[128] = {

/* 0x00 */ -5, /* 0x01 */ -3, /* 0x02 */ -3, /* 0x03 */ -3,

/* 0x04 */ -3, /* 0x05 */ -3, /* 0x06 */ -3, /* 0x07 */ -3,

/* 0x08 */ -3, /* 0x09 */ -2, /* 0x0a */ -2, /* 0x0b */ -2,

/* 0x0c */ -2, /* 0x0d */ -2, /* 0x0e */ -3, /* 0x0f */ -3,

/* 0x10 */ -3, /* 0x11 */ -3, /* 0x12 */ -3, /* 0x13 */ -3,

/* 0x14 */ -3, /* 0x15 */ -3, /* 0x16 */ -3, /* 0x17 */ -3,

/* 0x18 */ -3, /* 0x19 */ -3, /* 0x1a */ -3, /* 0x1b */ -3,

/* 0x1c */ -3, /* 0x1d */ -3, /* 0x1e */ -3, /* 0x1f */ -3,

/* ' ' */ -2, /* '!' */ -3, /* '"' */ -3, /* '#' */ -3,

/* '$' */ -3, /* '%' */ -3, /* '&' */ -3, /* ''' */ -3,

/* '(' */ -3, /* ')' */ -3, /* '*' */ -3, /* '+' */ 62,

/* ',' */ -3, /* '-' */ -3, /* '.' */ -3, /* '/' */ 63,

/* '0' */ 52, /* '1' */ 53, /* '2' */ 54, /* '3' */ 55,

/* '4' */ 56, /* '5' */ 57, /* '6' */ 58, /* '7' */ 59,

/* '8' */ 60, /* '9' */ 61, /* ':' */ -3, /* ';' */ -3,

/* '<' */ -3, /* '=' */ -1, /* '>' */ -3, /* '?' */ -3,

/* '@' */ -3, /* 'A' */ 0, /* 'B' */ 1, /* 'C' */ 2,

/* 'D' */ 3, /* 'E' */ 4, /* 'F' */ 5, /* 'G' */ 6,

/* 'H' */ 7, /* 'I' */ 8, /* 'J' */ 9, /* 'K' */ 10,

/* 'L' */ 11, /* 'M' */ 12, /* 'N' */ 13, /* 'O' */ 14,

/* 'P' */ 15, /* 'Q' */ 16, /* 'R' */ 17, /* 'S' */ 18,

/* 'T' */ 19, /* 'U' */ 20, /* 'V' */ 21, /* 'W' */ 22,

/* 'X' */ 23, /* 'Y' */ 24, /* 'Z' */ 25, /* '[' */ -3,

/* '\' */ -3, /* ']' */ -3, /* '^' */ -3, /* '_' */ -3,

/* '`' */ -3, /* 'a' */ 26, /* 'b' */ 27, /* 'c' */ 28,

/* 'd' */ 29, /* 'e' */ 30, /* 'f' */ 31, /* 'g' */ 32,

/* 'h' */ 33, /* 'i' */ 34, /* 'j' */ 35, /* 'k' */ 36,

/* 'l' */ 37, /* 'm' */ 38, /* 'n' */ 39, /* 'o' */ 40,

/* 'p' */ 41, /* 'q' */ 42, /* 'r' */ 43, /* 's' */ 44,

/* 't' */ 45, /* 'u' */ 46, /* 'v' */ 47, /* 'w' */ 48,

/* 'x' */ 49, /* 'y' */ 50, /* 'z' */ 51, /* '{' */ -3,

/* '|' */ -3, /* '}' */ -3, /* '~' */ -3, /* 0x7f */ -3

};

const UInt8 kBits_00000011 = 0x03;

const UInt8 kBits_00001111 = 0x0F;

const UInt8 kBits_00110000 = 0x30;

const UInt8 kBits_00111100 = 0x3C;

const UInt8 kBits_00111111 = 0x3F;

const UInt8 kBits_11000000 = 0xC0;

const UInt8 kBits_11110000 = 0xF0;

const UInt8 kBits_11111100 = 0xFC;

size_t EstimateBas64EncodedDataSize(size_t inDataSize)

{

size_t theEncodedDataSize = (int)ceil(inDataSize / 3.0) * 4;

theEncodedDataSize = theEncodedDataSize / 72 * 74 + theEncodedDataSize % 72;

return(theEncodedDataSize);

}

size_t EstimateBas64DecodedDataSize(size_t inDataSize)

{

size_t theDecodedDataSize = (int)ceil(inDataSize / 4.0) * 3;

//theDecodedDataSize = theDecodedDataSize / 72 * 74 + theDecodedDataSize % 72;

return(theDecodedDataSize);

}

bool Base64EncodeData(const void *inInputData, size_t inInputDataSize, char *outOutputData, size_t *ioOutputDataSize, BOOL wrapped)

{

size_t theEncodedDataSize = EstimateBas64EncodedDataSize(inInputDataSize);

if (*ioOutputDataSize < theEncodedDataSize)

return(false);

*ioOutputDataSize = theEncodedDataSize;

const UInt8 *theInPtr = (const UInt8 *)inInputData;

UInt32 theInIndex = 0, theOutIndex = 0;

for (; theInIndex < (inInputDataSize / 3) * 3; theInIndex += 3)

{

outOutputData[theOutIndex++] = kBase64EncodeTable[(theInPtr[theInIndex] & kBits_11111100) >> 2];

outOutputData[theOutIndex++] = kBase64EncodeTable[(theInPtr[theInIndex] & kBits_00000011) << 4 | (theInPtr[theInIndex + 1] & kBits_11110000) >> 4];

outOutputData[theOutIndex++] = kBase64EncodeTable[(theInPtr[theInIndex + 1] & kBits_00001111) << 2 | (theInPtr[theInIndex + 2] & kBits_11000000) >> 6];

outOutputData[theOutIndex++] = kBase64EncodeTable[(theInPtr[theInIndex + 2] & kBits_00111111) >> 0];

if (wrapped && (theOutIndex % 74 == 72))

{

outOutputData[theOutIndex++] = '\r';

outOutputData[theOutIndex++] = '\n';

}

}

const size_t theRemainingBytes = inInputDataSize - theInIndex;

if (theRemainingBytes == 1)

{

outOutputData[theOutIndex++] = kBase64EncodeTable[(theInPtr[theInIndex] & kBits_11111100) >> 2];

outOutputData[theOutIndex++] = kBase64EncodeTable[(theInPtr[theInIndex] & kBits_00000011) << 4 | (0 & kBits_11110000) >> 4];

outOutputData[theOutIndex++] = '=';

outOutputData[theOutIndex++] = '=';

if (wrapped && (theOutIndex % 74 == 72))

{

outOutputData[theOutIndex++] = '\r';

outOutputData[theOutIndex++] = '\n';

}

}

else if (theRemainingBytes == 2)

{

outOutputData[theOutIndex++] = kBase64EncodeTable[(theInPtr[theInIndex] & kBits_11111100) >> 2];

outOutputData[theOutIndex++] = kBase64EncodeTable[(theInPtr[theInIndex] & kBits_00000011) << 4 | (theInPtr[theInIndex + 1] & kBits_11110000) >> 4];

outOutputData[theOutIndex++] = kBase64EncodeTable[(theInPtr[theInIndex + 1] & kBits_00001111) << 2 | (0 & kBits_11000000) >> 6];

outOutputData[theOutIndex++] = '=';

if (wrapped && (theOutIndex % 74 == 72))

{

outOutputData[theOutIndex++] = '\r';

outOutputData[theOutIndex++] = '\n';

}

}

return(true);

}

bool Base64DecodeData(const void *inInputData, size_t inInputDataSize, void *ioOutputData, size_t *ioOutputDataSize)

{

memset(ioOutputData, '.', *ioOutputDataSize);

size_t theDecodedDataSize = EstimateBas64DecodedDataSize(inInputDataSize);

if (*ioOutputDataSize < theDecodedDataSize)

return(false);

*ioOutputDataSize = 0;

const UInt8 *theInPtr = (const UInt8 *)inInputData;

UInt8 *theOutPtr = (UInt8 *)ioOutputData;

size_t theInIndex = 0, theOutIndex = 0;

UInt8 theOutputOctet;

size_t theSequence = 0;

for (; theInIndex < inInputDataSize; )

{

SInt8 theSextet = 0;

SInt8 theCurrentInputOctet = theInPtr[theInIndex];

theSextet = kBase64DecodeTable[theCurrentInputOctet];

if (theSextet == -1)

break;

while (theSextet == -2)

{

theCurrentInputOctet = theInPtr[++theInIndex];

theSextet = kBase64DecodeTable[theCurrentInputOctet];

}

while (theSextet == -3)

{

theCurrentInputOctet = theInPtr[++theInIndex];

theSextet = kBase64DecodeTable[theCurrentInputOctet];

}

if (theSequence == 0)

{

theOutputOctet = (theSextet >= 0 ? theSextet : 0) << 2 & kBits_11111100;

}

else if (theSequence == 1)

{

theOutputOctet |= (theSextet >- 0 ? theSextet : 0) >> 4 & kBits_00000011;

theOutPtr[theOutIndex++] = theOutputOctet;

}

else if (theSequence == 2)

{

theOutputOctet = (theSextet >= 0 ? theSextet : 0) << 4 & kBits_11110000;

}

else if (theSequence == 3)

{

theOutputOctet |= (theSextet >= 0 ? theSextet : 0) >> 2 & kBits_00001111;

theOutPtr[theOutIndex++] = theOutputOctet;

}

else if (theSequence == 4)

{

theOutputOctet = (theSextet >= 0 ? theSextet : 0) << 6 & kBits_11000000;

}

else if (theSequence == 5)

{

theOutputOctet |= (theSextet >= 0 ? theSextet : 0) >> 0 & kBits_00111111;

theOutPtr[theOutIndex++] = theOutputOctet;

}

theSequence = (theSequence + 1) % 6;

if (theSequence != 2 && theSequence != 4)

theInIndex++;

}

*ioOutputDataSize = theOutIndex;

return(true);

}