StackOverflow2013

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copied!<p>This <strong><em>solution</em></strong> should be pretty straight forward, which includes all the methods to populate the missing information. Tested and functional within the sandbox.</p> <pre><code>// single base64 character conversion static int POS(char c) { if (c>='A' && c<='Z') return c - 'A'; if (c>='a' && c<='z') return c - 'a' + 26; if (c>='0' && c<='9') return c - '0' + 52; if (c == '+') return 62; if (c == '/') return 63; if (c == '=') return -1; [NSException raise:@"invalid BASE64 encoding" format:@"Invalid BASE64 encoding"]; return 0; } - (NSString *)encodeBase64:(const uint8_t *)input length:(NSInteger)length { return [NSString stringWithUTF8String:base64_encode(input, (size_t)length)]; } - (NSString *)decodeBase64:(NSString *)input length:(NSInteger *)length { size_t retLen; uint8_t *retStr = base64_decode([input UTF8String], &retLen); if (length) *length = (NSInteger)retLen; NSString *st = [[[NSString alloc] initWithBytes:retStr length:retLen encoding:NSUTF8StringEncoding] autorelease]; free(retStr); // If base64_decode returns dynamically allocated memory return st; } char* base64_encode(const void* buf, size_t size) { static const char base64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; char* str = (char*) malloc((size+3)*4/3 + 1); char* p = str; unsigned char* q = (unsigned char*) buf; size_t i = 0; while(i < size) { int c = q[i++]; c *= 256; if (i < size) c += q[i]; i++; c *= 256; if (i < size) c += q[i]; i++; *p++ = base64[(c & 0x00fc0000) >> 18]; *p++ = base64[(c & 0x0003f000) >> 12]; if (i > size + 1) *p++ = '='; else *p++ = base64[(c & 0x00000fc0) >> 6]; if (i > size) *p++ = '='; else *p++ = base64[c & 0x0000003f]; } *p = 0; return str; } void* base64_decode(const char* s, size_t* data_len_ptr) { size_t len = strlen(s); if (len % 4) [NSException raise:@"Invalid input in base64_decode" format:@"%d is an invalid length for an input string for BASE64 decoding", len]; unsigned char* data = (unsigned char*) malloc(len/4*3); int n[4]; unsigned char* q = (unsigned char*) data; for(const char*p=s; *p; ) { n[0] = POS(*p++); n[1] = POS(*p++); n[2] = POS(*p++); n[3] = POS(*p++); if (n[0]==-1 || n[1]==-1) [NSException raise:@"Invalid input in base64_decode" format:@"Invalid BASE64 encoding"]; if (n[2]==-1 && n[3]!=-1) [NSException raise:@"Invalid input in base64_decode" format:@"Invalid BASE64 encoding"]; q[0] = (n[0] << 2) + (n[1] >> 4); if (n[2] != -1) q[1] = ((n[1] & 15) << 4) + (n[2] >> 2); if (n[3] != -1) q[2] = ((n[2] & 3) << 6) + n[3]; q += 3; } // make sure that data_len_ptr is not null if (!data_len_ptr) [NSException raise:@"Invalid input in base64_decode" format:@"Invalid destination for output string length"]; *data_len_ptr = q-data - (n[2]==-1) - (n[3]==-1); return data; } </code></pre>

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