Convert string to binary then back again using PHP

Question

Is there a way to convert a string to binary then back again in the standard PHP library   To clarify what I m trying to do is store a password on a database  I m going to convert it first using a hash function then eventually store it as binary     I ve found the best way is to use this function  Seems to hash and output in binary at the same time   http   php net manual en function hash-hmac php

User · Answer

I would most definitely recommend using the built in standard password libraries that come with PHP  - Here is a good example on how to use them     For those coming here to figure out how to go from Binary Strings to Decimals and back  there are some good examples below    For converting binary  strings  to decimals chars you can do something like this      echo bindec  00000001       n   echo bindec  00000010       n   echo bindec  00000100       n   echo bindec  00001000       n   echo bindec  00010000       n   echo bindec  00100000       n   echo bindec  01000000       n   echo bindec  10000000       n   echo bindec  01000001       n      big binary string echo bindec  111010110111011110000110001     n     The above outputs   1 2 4 8 16 32 64 128 65 123452465     For converting decimals to char strings you can do this     convert to binary strings  00000001  echo decbin 1      n   echo decbin 2      n   echo decbin 4      n   echo decbin 8      n   echo decbin 16      n   echo decbin 32      n   echo decbin 64      n   echo decbin 128      n      convert a ascii character echo str pad decbin 65   8  0  STR PAD LEFT     n      convert a  char  echo str pad decbin ord  A     8  0  STR PAD LEFT     n      big number    echo str pad decbin 65535   8  0  STR PAD LEFT     n   echo str pad decbin 123452465   8  0  STR PAD LEFT     n     The above outputs   1 10 100 1000 10000 100000 1000000 10000000 01000001 01000001 1111111111111111 111010110111011110000110001

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You want to use pack and base convert      Convert a string into binary    Should output  0101001101110100011000010110001101101011  value   unpack  H     Stack    echo base convert  value 1   16  2       Convert binary into a string    Should output  Stack echo pack  H    base convert  0101001101110100011000010110001101101011   2  16

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easiest way I found was to convert to HEX instead of a string  If it works for you    hex   bin2hex  bin      It will convert a binary data to its hex representation   bin   pack  H      hex      It will convert a hex to binary   OR   bin   hex2bin  hex      Available only on PHP 5 4

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Why you are using PHP for the conversion  Now  there are so many front end languages available  Why you are still including a server  You can convert the password into the binary number in the front-end and send the converted string in the Database  According to my point of view  this would be convenient   var bintext  textresult     binlength      this aaa   this text value      bintext   this aaa replace    01  g               binlength   bintext length- bintext length 8           for var z 0  z lt binlength  z z 8                textresult    String fromCharCode parseInt bintext substr z 8  2                                this ans   textresult    This is a Javascript code which I have found here  http   binarytotext net   they have used this code with Vue js  In the code  this aaa is the v-model dynamic value  To convert the binary into the text values  they have used big numbers  You need to install an additional package and convert it back into the text field  In my point of view  it would be easy

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Anyone who is here in 2021  can use  SteeveDroz answer  but unfortunately  that is only for 1 character  So I put it into a for loop to loop through and change each character of the string  The Functions      function binary encode  str            bin    quot  quot           for  i   0   j   strlen  str    i  lt   j   i     bin    decbin ord  str  i       quot   quot            bin   substr  bin  0  strlen  bin  - 1           return  bin            function binary decode  bin            char   explode       bin            nstr               foreach  char as  ch   nstr    chr bindec  ch            return  nstr         Usage   bin   binary encode  quot String Here quot     str   binary decode  quot 1010011 1110100 1110010 1101001 1101110 1100111 100000 1001000 1100101 1110010 1100101 quot     Live Demo  http   sandbox onlinephpfunctions com code 2553fc9e26c5148fddbb3486091d119aa59ae464

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Yes  sure   There      bin   decbin ord  char          and back again    char   chr bindec  bin

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i was looking for some string bits conversion and got here   If the next case is for you take   it so     if you want to use the bits from a string into different bits  maybe this example would help   string  1001     this would be 2 0 1     0    2 3 1 1 8 9  bit4  string 0    1  bit3  string 1    bit2  string 2    bit1  string 3    1

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That s funny how Stefan Gehrig his answer is actually the correct one  You don t need to convert a string into a  011010101  string to store it in BINARY field in a database  Anyway since this is the first answer that comes up when you google for  php convert string to binary string   Here is my contribution to this problem   The most voted answer by Francois Deschenes goes wrong for long strings  either bytestrings or bitstrings  that is because     base convert   may lose precision on large numbers due to properties related to the internal  double  or  float  type used  Please see the Floating point numbers section in the manual for more specific information and limitations    From  https   secure php net manual en function base-convert php  To work around this limitation you can chop up the input string into chunks  The functions below implement this technique    lt  php  function bytesToBits string  bytestring      if   bytestring         return         bitstring         foreach  str split  bytestring  4  as  chunk         bitstring    str pad base convert unpack  H     chunk  1   16  2   strlen  chunk    8   0   STR PAD LEFT          return  bitstring     function bitsToBytes string  bitstring      if   bitstring         return           We want all bits to be right-aligned    bitstring len   strlen  bitstring     if   bitstring len   8  gt  0         bitstring   str pad  bitstring  intdiv  bitstring len   8  8    8   0   STR PAD LEFT           bytestring         foreach  str split  bitstring  32  as  chunk         bytestring    pack  H    str pad base convert  chunk  2  16   strlen  chunk    4   0   STR PAD LEFT           return  bytestring     for   i   0   i  lt  10000   i         bytestring in   substr hash  sha512   uniqid     true    0  rand 0  128       bits   bytesToBits  bytestring in      bytestring out   bitsToBytes  bits     if   bytestring in      bytestring out        printf  IN     s n    bytestring in       printf  BITS   s n    bits       printf  OUT    s n    bytestring out       var dump  bytestring in   bytestring out      printf   doesn t show some characters        die  Error in functions  1              for   i   0   i  lt  10000   i         len   rand 0  128      bitstring in         for   j   0   j  lt    len   j           bitstring in     string  rand 0 1          bytes   bitsToBytes  bitstring in      bitstring out   bytesToBits  bytes         since converting to byte we always have a multitude of 4  so we need to correct the bitstring in to compare       bitstring in old    bitstring in     bitstring in len   strlen  bitstring in     if   bitstring in len   8  gt  0         bitstring in   str pad  bitstring in  intdiv  bitstring in len   8  8    8   0   STR PAD LEFT          if   bitstring in      bitstring out        printf  IN1     s n    bitstring in old       printf  IN2     s n    bitstring in       printf  BYTES   s n    bytes       printf  OUT     s n    bitstring out       var dump  bytes      printf   doesn t show some characters        die  Error in functions  2             echo  All ok     PHP EOL    Note that if you insert a bitstring that is not a multitude of 8  example   101   you will not be able to recover the original bitstring when you converted to bytestring  From the bytestring converting back  uyou will get  00000101  which is numerically the same  unsigned 8 bit integer  but has a different string length  Therefor if the bitstring length is important to you you should save the length in a separate variable and chop of the first part of the string after converting    bits in    101    bits in len   strlen  bits in       lt -- keep track if input length  bits out   bytesToBits bitsToBytes  101     var dump  bits in   bits out  substr  bits out  -  bits in len       recover original length with substr

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A string is just a sequence of bytes  hence it s actually binary data in PHP  What exactly are you trying to do   EDIT  If you want to store binary data in your database  the problem most often is the column definition in your database  PHP does not  differentiate between binary data and strings  but databases do  In MySQL for example you should store binary data in BINARY  VARBINARY or BLOB columns    Another option would be to base64 encode your PHP string and store it in some VARCHAR or TEXT column in the database  But be aware that the string s length will increase when base64 encode is used

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Strings in PHP are always BLOBs  So you can use a string to hold the value for your database BLOB  All of this stuff base-converting and so on has to do with presenting that BLOB   If you want a nice human-readable representation of your BLOB then it makes sense to show the bytes it contains  and probably to use hex rather than decimal  Hence  the string  41 42 43  is a good way to present the byte array that in C  would be   var bytes   new byte     0x41  0x42  0x43      but it is obviously not a good way to represent those bytes  The string  ABC  is an efficient representation  because it is in fact the same BLOB  only it s not so Large in this case     In practice you will typically get your BLOBs from functions that return string - such as that hashing function  or other built-in functions like fread   In the rare cases  but not so rare when just trying things out prototyping  that you need to just construct a string from some hard-coded bytes I don t know of anything more efficient than converting a  hex string  to what is often called a  binary string  in PHP    myBytes    414243    data   pack  H     myBytes     If you var dump  data   it ll show you string 3   ABC   That s because 0x41   65 decimal    A   in basically all encodings     Since looking at binary data by interpreting it as a string is not exactly intuitive  you may want to make a basic wrapper to make debugging easier  One possible such wrapper is  class blob       function   construct  hexStr                      this- gt appendHex  hexStr              public  value       public function appendHex  hexStr                 this- gt value    pack  H     hexStr              public function getByte  index                return unpack  C    this- gt value  index   1              public function setByte  index   value                 this- gt value  index    pack  C    value              public function toArray                 return unpack  C     this- gt value             This is something I cooked up on the fly  and probably just a starting point for your own wrapper  But the idea is to use a string for storage since this is the most efficient structure available in PHP  while providing methods like toArray   for use in debugger watches evaluations when you want to examine the contents    Of course you may use a perfectly straightforward PHP array instead and pack it to a string when interfacing with something that uses strings for binary data  Depending on the degree to which you are actually going to modify the blob this may prove easier  and although it isn t space efficient I think you d get acceptable performance for many tasks   An example to illustrate the functionality      Construct a blob with 3 bytes  0x41 0x42 0x43   b   new blob  414243        Append 3 more bytes  0x44 0x45 0x46   b- gt appendHex  444546        Change the second byte to 0x41  so we now have 0x41 0x41 0x43 0x44 0x45 0x46    b- gt setByte 1  0x41      or  equivalently  setByte 1  65      Dump the first byte  var dump  b- gt getByte 0        Verify the result  The string  AACDEF   because it s only ASCII characters  will have the same binary representation in basically any encoding   ok    b- gt value     AACDEF

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Your hash is already binary and ready to be used with your database   However you must need to convert it into a format the database column definition expects   Any string in PHP  until 5 3  is a binary string  That means it contains only binary data    However because of backwards compatiblity with PHP 6 you can already cast your string explicitly as binary     string    my binary string     binary   b my binary string     But that is merely for compatibility reasons  in your code you can just do      string    binary      convert  binary string into string    binary    string      convert  string into binary string   Because it s the same  The  convert  is superfluous

[php] Convert string to binary then back again using PHP

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