PHP实现AES256加密算法实例_PHP教程

1

2

立即学习“PHP免费学习笔记（深入）”；

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

61

62

63

64

65

66

67

68

69

70

71

72

73

74

75

76

77

78

79

80

81

82

83

84

85

86

87

88

89

90

91

92

93

94

95

96

97

98

99

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

152

153

154

155

156

157

158

159

160

161

162

163

164

165

166

167

168

169

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */ 

/* AES counter (CTR) mode implementation in PHP (c) Chris Veness 2005-2011. Right of free use is */ 

/*  granted for all commercial or non-commercial use under CC-BY licence. No warranty of any  */ 

/*  form is offered.                                      */ 

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */ 

class AesCtr extends Aes { 

 /** 

  * Encrypt a text using AES encryption in Counter mode of operation 

  * - see http://csrc.nist.gov/publications/nistpubs/800-38a/sp800-38a.pdf 

  * 

  * Unicode multi-byte character safe 

  * 

  * @param plaintext source text to be encrypted 

  * @param password the password to use to generate a key 

  * @param nBits   number of bits to be used in the key (128, 192, or 256) 

  * @param keep   keep 1:each not change 0:each change(default) 

  * @return     encrypted text 

  */ 

 public static function encrypt($plaintext, $password, $nBits, $keep=0) { 

  $blockSize = 16; // block size fixed at 16 bytes / 128 bits (Nb=4) for AES 

  if (!($nBits==128 || $nBits==192 || $nBits==256)) return ''; // standard allows 128/192/256 bit keys 

  // note PHP (5) gives us plaintext and password in UTF8 encoding! 

  // use AES itself to encrypt password to get cipher key (using plain password as source for  

  // key expansion) - gives us well encrypted key 

  $nBytes = $nBits/8; // no bytes in key 

  $pwBytes = array(); 

  for ($i=0; $i

  $key = Aes::cipher($pwBytes, Aes::keyExpansion($pwBytes)); 

  $key = array_merge($key, array_slice($key, 0, $nBytes-16)); // expand key to 16/24/32 bytes long  

  // initialise 1st 8 bytes of counter block with nonce (NIST SP800-38A §B.2): [0-1] = millisec,  

  // [2-3] = random, [4-7] = seconds, giving guaranteed sub-ms uniqueness up to Feb 2106 

  $counterBlock = array(); 

  if($keep==0){ 

    $nonce = floor(microtime(true)*1000);  // timestamp: milliseconds since 1-Jan-1970 

    $nonceMs = $nonce%1000; 

    $nonceSec = floor($nonce/1000); 

    $nonceRnd = floor(rand(0, 0xffff)); 

  }else{ 

    $nonce = 10000; 

    $nonceMs = $nonce%1000; 

    $nonceSec = floor($nonce/1000); 

    $nonceRnd = 10000; 

  }   

  for ($i=0; $i

  for ($i=0; $i

  for ($i=0; $i

  // and convert it to a string to go on the front of the ciphertext 

  $ctrTxt = ''; 

  for ($i=0; $i

  // generate key schedule - an expansion of the key into distinct Key Rounds for each round 

  $keySchedule = Aes::keyExpansion($key); 

  //print_r($keySchedule); 

  $blockCount = ceil(strlen($plaintext)/$blockSize); 

  $ciphertxt = array(); // ciphertext as array of strings 

  for ($b=0; $b

   // set counter (block #) in last 8 bytes of counter block (leaving nonce in 1st 8 bytes) 

   // done in two stages for 32-bit ops: using two words allows us to go past 2^32 blocks (68GB) 

   for ($c=0; $c

   for ($c=0; $c

   $cipherCntr = Aes::cipher($counterBlock, $keySchedule); // -- encrypt counter block -- 

   // block size is reduced on final block 

   $blockLength = $b

   $cipherByte = array(); 

   for ($i=0; $i

    $cipherByte[$i] = $cipherCntr[$i] ^ ord(substr($plaintext, $b*$blockSize+$i, 1)); 

    $cipherByte[$i] = chr($cipherByte[$i]); 

   } 

   $ciphertxt[$b] = implode('', $cipherByte); // escape troublesome characters in ciphertext 

  } 

  // implode is more efficient than repeated string concatenation 

  $ciphertext = $ctrTxt . implode('', $ciphertxt); 

  $ciphertext = base64_encode($ciphertext); 

  return $ciphertext; 

 } 

 /** 

  * Decrypt a text encrypted by AES in counter mode of operation 

  * 

  * @param ciphertext source text to be decrypted 

  * @param password  the password to use to generate a key 

  * @param nBits   number of bits to be used in the key (128, 192, or 256) 

  * @return      decrypted text 

  */ 

 public static function decrypt($ciphertext, $password, $nBits) { 

  $blockSize = 16; // block size fixed at 16 bytes / 128 bits (Nb=4) for AES 

  if (!($nBits==128 || $nBits==192 || $nBits==256)) return ''; // standard allows 128/192/256 bit keys 

  $ciphertext = base64_decode($ciphertext); 

  // use AES to encrypt password (mirroring encrypt routine) 

  $nBytes = $nBits/8; // no bytes in key 

  $pwBytes = array(); 

  for ($i=0; $i

  $key = Aes::cipher($pwBytes, Aes::keyExpansion($pwBytes)); 

  $key = array_merge($key, array_slice($key, 0, $nBytes-16)); // expand key to 16/24/32 bytes long 

  // recover nonce from 1st element of ciphertext 

  $counterBlock = array(); 

  $ctrTxt = substr($ciphertext, 0, 8); 

  for ($i=0; $i

  // generate key schedule 

  $keySchedule = Aes::keyExpansion($key); 

  // separate ciphertext into blocks (skipping past initial 8 bytes) 

  $nBlocks = ceil((strlen($ciphertext)-8) / $blockSize); 

  $ct = array(); 

  for ($b=0; $b

  $ciphertext = $ct; // ciphertext is now array of block-length strings 

  // plaintext will get generated block-by-block into array of block-length strings 

  $plaintxt = array(); 

  for ($b=0; $b

   // set counter (block #) in last 8 bytes of counter block (leaving nonce in 1st 8 bytes) 

   for ($c=0; $c

   for ($c=0; $c

   $cipherCntr = Aes::cipher($counterBlock, $keySchedule); // encrypt counter block 

   $plaintxtByte = array(); 

   for ($i=0; $i

    // -- xor plaintext with ciphered counter byte-by-byte -- 

    $plaintxtByte[$i] = $cipherCntr[$i] ^ ord(substr($ciphertext[$b],$i,1)); 

    $plaintxtByte[$i] = chr($plaintxtByte[$i]); 

   } 

   $plaintxt[$b] = implode('', $plaintxtByte);  

  } 

  // join array of blocks into single plaintext string 

  $plaintext = implode('',$plaintxt); 

  return $plaintext; 

 } 

 /* 

  * Unsigned right shift function, since PHP has neither >>> operator nor unsigned ints 

  * 

  * @param a number to be shifted (32-bit integer) 

  * @param b number of bits to shift a to the right (0..31) 

  * @return  a right-shifted and zero-filled by b bits 

  */ 

 private static function urs($a, $b) { 

  $a &= 0xffffffff; $b &= 0x1f; // (bounds check) 

  if ($a&0x80000000 && $b>0) {  // if left-most bit set 

   $a = ($a>>1) & 0x7fffffff;  //  right-shift one bit & clear left-most bit 

   $a = $a >> ($b-1);      //  remaining right-shifts 

  } else {            // otherwise 

   $a = ($a>>$b);        //  use normal right-shift 

  }  

  return $a;  

 } 

}  

?>