Partager via

5.1.3 DES-ECB-LM Cipher Definition

  • Article

des_ecb_lm_dec utilizes DES-ECB-LM in cipher-mode decryption.

des_ecb_lm_enc utilizes DES-ECB-LM in cipher-mode encryption.

DES-ECB-LM is defined as follows.

 des_ecb_lm( input:byte[8], encryptionKey: byte[8], 
             output:byte[8])
 InputKey:byte[7]
 OutputKey:byte[8]
 Let InputKey be the first 7 bytes of encryptionKey [0-6]
     OutputKey[0] = InputKey[0] >> 0x01;
     OutputKey[1] = ((InputKey[0]&0x01)<<6) | (InputKey[1]>>2);
     OutputKey[2] = ((InputKey[1]&0x03)<<5) | (InputKey[2]>>3);
     OutputKey[3] = ((InputKey[2]&0x07)<<4) | (InputKey[3]>>4);
     OutputKey[4] = ((InputKey[3]&0x0F)<<3) | (InputKey[4]>>5);
     OutputKey[5] = ((InputKey[4]&0x1F)<<2) | (InputKey[5]>>6);
     OutputKey[6] = ((InputKey[5]&0x3F)<<1) | (InputKey[6]>>7);
     OutputKey[7] = InputKey[6] & 0x7F;
     ((unsigned long*)OutputKey)[0] <<= 1;
     ((unsigned long*)OutputKey)[1] <<= 1;
     ((unsigned long*)OutputKey)[0] &= 0xfefefefe;
     ((unsigned long*)OutputKey)[1] &= 0xfefefefe;
 Let the left-most bit of OutputKey be the parity bit. That is,
 if the sum of the other 7 bits is odd, the parity bit is zero;
 otherwise the parity bit is one. The processing starts at the
 left-most bit of OutputKey.
 des_ecb( input, OutputKey, output )
 END
 

The algorithm des_ecb is the Data Encryption Standard (DES) encryption in Electronic Code Book (ECB) mode, as specified in [FIPS81].