Base64 can transcode binary characters into visible characters for HTTP transmission, but Base64 transcoding will generate "+", "/", "=" and other special characters transcoded by the URL, resulting in inconsistency between the two aspects.
We can replace "+", "/", and "=" with characters that do not transcode URLs before sending, and then replace these characters back after receiving the data and then decode them.
PHP：
/**
* URL base64 decoding
* '-' -> '+'
* '_' -> '/'
* The remainder of string length %4, complement '='
* @param unknown $string
*/
public static function urlsafe_b64decode($string) {
$data = str_replace(array('-','_'),array('+','/'),$string);
$mod4 = strlen($data) % 4;
if ($mod4) {
$data .= substr('====', $mod4);
}
return base64_decode($data);
}
/**
* URL base64 encoded
* '+' -> '-'
* '/' -> '_'
* '=' -> ''
* @param unknown $string
*/
function urlsafe_b64encode($string) {
$data = base64_encode($string);
$data = str_replace(array('+','/','='),array('-','_',''),$data);
return $data;
}
OC:
#pragma - Convert the strings "-", "_" in saveBase64 encoding to "+", "/", and the bit complement with 4 times the length of the string "="
+(NSData*)safeUrlBase64Decode:(NSString*)safeUrlbase64Str
{
// '-' -> '+'
// '_' -> '/'
If it is less than 4 times the length, make up for '='
NSMutableString * base64Str = [[NSMutableString alloc]initWithString:safeUrlbase64Str];
base64Str = (NSMutableString * )[base64Str stringByReplacingOccurrencesOfString:@"-" withString:@"+"];
base64Str = (NSMutableString * )[base64Str stringByReplacingOccurrencesOfString:@"_" withString:@"/"];
NSInteger mod4 = base64Str.length % 4;
if(mod4 > 0)
[base64Str appendString:[@"====" substringToIndex:(4-mod4)]];
NSLog(@"Base64 original: %@", base64Str);
return [GTMBase64 decodeData:[base64Str dataUsingEncoding:NSUTF8StringEncoding]];
}
#pragma - Base64 encoding contains +, /, = these insecure URL strings, so change characters
+(NSString*)safeUrlBase64Encode:(NSData*)data
{
// '+' -> '-'
// '/' -> '_'
// '=' -> ''
NSString * base64Str = [GTMBase64 stringByEncodingData:data];
NSMutableString * safeBase64Str = [[NSMutableString alloc]initWithString:base64Str];
safeBase64Str = (NSMutableString * )[safeBase64Str stringByReplacingOccurrencesOfString:@"+" withString:@"-"];
safeBase64Str = (NSMutableString * )[safeBase64Str stringByReplacingOccurrencesOfString:@"/" withString:@"_"];
safeBase64Str = (NSMutableString * )[safeBase64Str stringByReplacingOccurrencesOfString:@"=" withString:@""];
NSLog(@"safeBase64encoded:%@", safeBase64Str);
return safeBase64Str;
}
Java：
public static String safeUrlBase64Encode(byte[] data){
String encodeBase64 = new BASE64Encoder().encode(data);
String safeBase64Str = encodeBase64.replace('+', '-');
safeBase64Str = safeBase64Str.replace('/', '_');
safeBase64Str = safeBase64Str.replaceAll("=", "");
return safeBase64Str;
}
public static byte[] safeUrlBase64Decode(final String safeBase64Str){
String base64Str = safeBase64Str.replace('-', '+');
base64Str = base64Str.replace('_', '/');
int mod4 = base64Str.length()%4;
if(mod4 > 0){
base64Str = base64Str + "====".substring(mod4);
}
return new BASE64Decoder().decodeBuffer(base64Str);
}
For Android, android.utils.Base64 comes with this feature:
Base64.encodeToString(encrypted, Base64.URL_SAFE| Base64.NO_WRAP);
Base64.decode(data, Base64.URL_SAFE); |
Posted on 11/15/2019 2:10:48 PM
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