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Diffstat (limited to 'src/a53f.c')
| -rw-r--r-- | src/a53f.c | 124 |
1 files changed, 124 insertions, 0 deletions
diff --git a/src/a53f.c b/src/a53f.c new file mode 100644 index 0000000..2932d6d --- /dev/null +++ b/src/a53f.c @@ -0,0 +1,124 @@ +/*--------------------------------------------------------- + * A5/3 + *--------------------------------------------------------- + * + * A sample implementation of A5/3, the functions of the + * A5/3 algorithm set. + * + * This has been coded for clarity, not necessarily for + * efficiency. + * + * This will compile and run correctly on both Intel + * (little endian) and Sparc (big endian) machines. + * + * Version 0.1 13 March 2002 + * + *---------------------------------------------------------*/ +#include "kasumi.h" +#include <stdlib.h> +void KGcore( u8 ca, u8 cb, u32 cc, u8 cd, u8 *ck, u8 *co, int cl ); + +/*--------------------------------------------------------- + * BuildKey() + * The KGcore() function expects a 128-bit key. This + * function builds that key from shorter length keys. + *---------------------------------------------------------*/ +static u8 *BuildKey( u8 *k, int len ) +{ + static u8 ck[16]; /* Where the key is built */ + int i, n, sf; + u8 mask[]={0x1,0x3,0x7,0xF,0x1F,0x3F,0x7F,0xFF}; + i = (len+7)/8; /* Round to nearest byte */ + if (i > 16 ) + i = 16; /* limit to 128 bits */ + for( n=0; n<i; ++n ) /* copy over the key */ + ck[n] = k[n]; + sf = len%8; /* Any odd key length? */ + /* If the key is less than 128-bits we need to replicate * + * it as many times as is necessary to fill the key. */ + if( len < 128 ) + { + n = 0; + if( sf ) /* Doesn't align to byte boundaries */ + { + ck[i-1] &= mask[sf]; + ck[i-1] += ck[0]<<sf; + while( i<16 ) + { + ck[i] = (ck[n]>>(8-sf)) + (ck[n+1]<<sf); + ++n; + ++i; + } + } + else + while( i<16 ) + ck[i++] = ck[n++]; + } + return( ck ); +} + +/*--------------------------------------------------------- + * The basic A5/3 functions. + * These follow a standard layout: + * - From the supplied key build the 128-bit required by + * KGcore() + * - Call the KGcora() function with te appropriate + * parameters + * - Take the generated Keystream and repackage it + * in the required format. + */ +/*--------------------------------------------------------- + * The standard GSM function + *---------------------------------------------------------*/ +void GSM( u8 *key, int klen, int count, u8 *block1, u8 *block2 ) +{ + u8 *ck, data[32]; + int i; + ck=BuildKey( key, klen ); + KGcore( 0x0F, 0, count, 0, ck, data, 228 ); + for( i=0; i<15; ++i ) + { + block1[i] = data[i]; + block2[i] = (data[i+14]<<2) + (data[i+15]>>6); + } + block1[14] &= 0xC0; + block2[14] &= 0xC0; +} + +/*--------------------------------------------------------- + * The standard GSM ECSD function + *---------------------------------------------------------*/ +void ECSD( u8 *key, int klen, int count, u8 *block1, u8 *block2 ) +{ + u8 *ck, data[87]; + int i; + ck=BuildKey( key, klen ); + KGcore( 0xF0, 0, count, 0, ck, data, 696 ); + for( i=0; i<44; ++i ) + { + block1[i] = data[i]; + block2[i] = (data[i+43]<<4) + (data[i+44]>>4); + } + block1[43] &= 0xF0; + block2[43] &= 0xF0; +} + +/*--------------------------------------------------------- + * The standard GEA3 function + *---------------------------------------------------------*/ +void GEA3( u8 *key, int klen, u32 input, u8 direction, u8 *block, int m ) +{ + u8 *ck, *data; + int i; + data = malloc( m ); + ck=BuildKey( key, klen ); + KGcore( 0xFF, 0, input, direction, ck, data, m*8 ); + for( i=0; i<m; ++i ) + block[i] = data[i]; + free( data ); +} + +/*--------------------------------------------------------- + * E n d o f A 5 3 f . c + *---------------------------------------------------------*/ + |