/tmp/pear-apidoc/Xtea.phpJeroen Derks Class that implements the xTEA encryption algorithm.<br /> This enables you to encrypt data without requiring mcrypt. From the C source: ----------------------------------------- The Tiny Encryption Algorithm (TEA) by David Wheeler and Roger Needham of the Cambridge Computer Laboratory. Placed in the Public Domain by David Wheeler and Roger Needham. **** ANSI C VERSION (New Variant) **** Notes: TEA is a Feistel cipher with XOR and and addition as the non-linear mixing functions. Takes 64 bits of data in v[0] and v[1]. Returns 64 bits of data in w[0] and w[1]. Takes 128 bits of key in k[0] - k[3]. TEA can be operated in any of the modes of DES. Cipher Block Chaining is, for example, simple to implement. n is the number of iterations. 32 is ample, 16 is sufficient, as few as eight may be OK. The algorithm achieves good dispersion after six iterations. The iteration count can be made variable if required. Note this is optimised for 32-bit CPUs with fast shift capabilities. It can very easily be ported to assembly language on most CPUs. delta is chosen to be the real part of (the golden ratio Sqrt(5/4) - 1/2 ~ 0.618034 multiplied by 2^32). This version has been amended to foil two weaknesses identified by David A. Wagner (daw@cs.berkeley.edu): 1) effective key length of old-variant TEA was 126 not 128 bits 2) a related key attack was possible although impractical. void encipher(unsigned long *const v,unsigned long *const w, const unsigned long *const k) { register unsigned long y=v[0],z=v[1],sum=0,delta=0x9E3779B9,n=32; while(n-->0) { y+= (z<<4 ^ z>>5) + z ^ sum + k[sum&3]; sum += delta; z+= (y<<4 ^ y>>5) + y ^ sum + k[sum>>11 & 3]; } w[0]=y; w[1]=z; } void decipher(unsigned long *const v,unsigned long *const w, const unsigned long *const k) { register unsigned long y=v[0],z=v[1],sum=0xC6EF3720, delta=0x9E3779B9,n=32; # sum = delta<<5, in general sum = delta * n while(n-->0) { z-= (y<<4 ^ y>>5) + y ^ sum + k[sum>>11 & 3]; sum -= delta; y-= (z<<4 ^ z>>5) + z ^ sum + k[sum&3]; } w[0]=y; w[1]=z; } -----------------------------------------Class that implements the xTEA encryption algorithm.$Revision: 1.13 $Jeroen DerkssetIter()Constructor, sets the number of iterations.Jeroen Derks$n_itergetIter()Number of iterations to use.Set the number of iterations to use.Jeroen Derks$n_itersetIter()Number of iterations to use.Get the number of iterations to use.Jeroen Derksdecrypt()_encipherLong()_resize()_str2long()Data to encrypt.Key to encrypt data with (binary string).Binary encrypted character string.Encrypt a string using a specific key.Jeroen Derks_encipherLong()encrypt()_resize()_str2long()Encrypted data to decrypt.Key to decrypt encrypted data with (binary string).Binary decrypted character string.Decrypt an encrypted string using a specific key.Jeroen Derks$n_iter_add()_rshift()_decipherLong()32 bits of data.32 bits of data.Placeholder for enciphered 64 bits (in w[0] and w[1]).Key 128 bits (in k[0]-k[3]).Encipher a single long (32-bit) value.Jeroen Derks$n_iter_add()_rshift()_decipherLong()32 bits of enciphered data.32 bits of enciphered data.Placeholder for deciphered 64 bits (in w[0] and w[1]).Key 128 bits (in k[0]-k[3]).Decipher a single long (32-bit) value.Jeroen DerksData string to resize to specified size.Size in bytes to align data to.Set to true if padded bytes should not be zero.Length of supplied data string.Resize data string to a multiple of specified size.Jeroen DerksHexadecimal string to convert to binary string.Binary string.Convert a hexadecimal string to a binary string (e.g. convert "616263" to "abc").Jeroen DerksIndex into $data_long for output.Input string.Output array of long.Index from which to optionally continue.Convert string to array of long.Jeroen DerksLong to convert to character string.Character string.Convert long to character string.Jeroen DerksHandle proper unsigned right shift, dealing with PHP's signed shift.2004/Sep/06Jeroen DerksHandle proper unsigned add, dealing with PHP's signed add.2004/Sep/06setIter()getIter()Number of iterations.