@ -1,51 +1,104 @@
// SPDX-License-Identifier: AGPL-3.0-only
/ * *
* Digital Voice Modem - D VM Console
* Digital Voice Modem - D esktop Dispatch Console
* AGPLv3 Open Source . Use is subject to license terms .
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER .
*
* @package DVM / D VM Console
* @package DVM / D esktop Dispatch Console
* @license AGPLv3 License ( https : //opensource.org/licenses/AGPL-3.0)
*
* Copyright ( C ) 2025 Caleb , K4PHP
*
* /
// TODO: Move to fnecore
using System ;
using System.Collections.Generic ;
using System.Security.Cryptography ;
using System.Linq ;
namespace DVMConsole
using fnecore.P25 ;
namespace dvmconsole
{
/// <summary>
///
/// </summary>
public class P25Crypto
{
private ProtocolType protocol ;
public const int IMBE_BUF_LEN = 11 ;
private byte algId ;
private ushort keyId ;
private byte [ ] messageIndicator = new byte [ 9 ] ;
private Dictionary < ushort , KeyInfo > keys = new Dictionary < ushort , KeyInfo > ( ) ;
private byte [ ] aesKeystream = new byte [ 240 ] ; // AES buffer
private byte [ ] adpKeystream = new byte [ 469 ] ; // ADP buffer
private int aesPosition ;
private int adpPosition ;
private int ksPosition ;
/ *
* * Class
* /
/// <summary>
///
/// </summary>
private class KeyInfo
{
/ *
* * Properties
* /
/// <summary>
///
/// </summary>
public byte AlgId { get ; }
/// <summary>
///
/// </summary>
public byte [ ] Key { get ; }
/// <summary>
/// Initializes a new instance of the <see cref="KeyInfo"/> class.
/// </summary>
/// <param name="algid"></param>
/// <param name="key"></param>
public KeyInfo ( byte algid , byte [ ] key )
{
AlgId = algid ;
Key = key ;
}
} // private class KeyInfo
/ *
* * Methods
* /
/// <summary>
/// Initializes a new instance of the <see cref="P25Crypto"/> class.
/// </summary>
public P25Crypto ( )
{
this . protocol = ProtocolType . Unknown ;
this . algId = 0x80 ;
this . algId = P25Defines . P25_ALGO_UNENCRYPT ;
this . keyId = 0 ;
this . aesPosition = 0 ;
this . adpPosition = 0 ;
this . ks Position = 0 ;
}
/// <summary>
///
/// </summary>
public void Reset ( )
{
keys . Clear ( ) ;
}
/// <summary>
///
/// </summary>
/// <param name="keyid"></param>
/// <param name="algid"></param>
/// <param name="key"></param>
public void AddKey ( ushort keyid , byte algid , byte [ ] key )
{
if ( keyid = = 0 | | algid = = 0x80 )
@ -54,58 +107,90 @@ namespace DVMConsole
keys [ keyid ] = new KeyInfo ( algid , key ) ;
}
/// <summary>
///
/// </summary>
/// <param name="keyId"></param>
/// <returns></returns>
public bool HasKey ( ushort keyId )
{
return keys . ContainsKey ( keyId ) ;
}
public bool Prepare ( byte algid , ushort keyid , ProtocolType protocol , byte [ ] MI )
/// <summary>
///
/// </summary>
/// <param name="algid"></param>
/// <param name="keyid"></param>
/// <param name="protocol"></param>
/// <param name="MI"></param>
/// <returns></returns>
public bool Prepare ( byte algid , ushort keyid , byte [ ] MI )
{
this . algId = algid ;
this . keyId = keyid ;
this . protocol = protocol ;
Array . Copy ( MI , this . messageIndicator , Math . Min ( MI . Length , this . messageIndicator . Length ) ) ;
if ( ! keys . ContainsKey ( keyid ) )
return false ;
if ( algid = = 0x84 ) // AES-256
this . ksPosition = 0 ;
if ( algid = = P25Defines . P25_ALGO_AES )
{
this . aesPosition = 0 ;
GenerateAesKeystream ( ) ;
GenerateAESKeystream ( ) ;
return true ;
}
else if ( algid = = 0xAA ) // ADP (RC4
else if ( algid = = P25Defines . P25_ALGO_ARC4
{
this . adpPosition = 0 ;
GenerateAdpKeystream ( ) ;
GenerateARC4Keystream ( ) ;
return true ;
}
return false ;
}
public bool Process ( byte [ ] PCW , FrameType frameType , int voiceSubframe )
/// <summary>
///
/// </summary>
/// <param name="imbe"></param>
/// <param name="duid"></param>
/// <returns></returns>
public bool Process ( byte [ ] imbe , P25DUID duid )
{
if ( ! keys . ContainsKey ( keyId ) )
return false ;
return algId switch
{
0x84 = > AesProcess ( PCW , frameType , voiceSubframe ) ,
0xAA = > AdpProcess ( PCW , frameType , voiceSubframe ) ,
P25Defines . P25_ALGO_AES = > AESProcess ( imbe , duid ) ,
P25Defines . P25_ALGO_ARC4 = > ARC4Process ( imbe , duid ) ,
_ = > false
} ;
}
/// <summary>
/// Create ADP key stream
///
/// </summary>
/// <param name="a"></param>
/// <param name="i1"></param>
/// <param name="i2"></param>
private void Swap ( byte [ ] a , int i1 , int i2 )
{
byte temp = a [ i1 ] ;
a [ i1 ] = a [ i2 ] ;
a [ i2 ] = temp ;
}
/// <summary>
/// Create ARC4 keystream.
/// </summary>
private void GenerateAdpKeystream ( )
private void GenerateA RC4 Keystream( )
{
byte [ ] adpKey = new byte [ 13 ] ;
byte [ ] S = new byte [ 256 ] ;
byte [ ] K = new byte [ 256 ] ;
byte [ ] permutation = new byte [ 256 ] ;
byte [ ] key = new byte [ 256 ] ;
if ( ! keys . ContainsKey ( keyId ) )
return ;
@ -127,141 +212,46 @@ namespace DVMConsole
adpKey [ i ] = messageIndicator [ i - 5 ] ;
}
// generate ARC4 keystream
// initialize state variable
for ( i = 0 ; i < 256 ; + + i )
{
K [ i ] = adpKey [ i % 13 ] ;
S [ i ] = ( byte ) i ;
key [ i ] = adpKey [ i % 13 ] ;
permutation [ i ] = ( byte ) i ;
}
// randomize, using key
for ( i = 0 ; i < 256 ; + + i )
{
j = ( j + S[ i ] + K [ i ] ) & 0xFF ;
Swap ( S , i , j ) ;
j = ( j + permutation[ i ] + key [ i ] ) & 0xFF ;
Swap ( permutation , i , j ) ;
}
// perform RC4 transformation
i = j = 0 ;
for ( k = 0 ; k < 469 ; + + k )
{
i = ( i + 1 ) & 0xFF ;
j = ( j + S [ i ] ) & 0xFF ;
Swap ( S , i , j ) ;
adpKeystream [ k ] = S [ ( S [ i ] + S [ j ] ) & 0xFF ] ;
}
}
/// <summary>
/// Preform a swap
/// </summary>
/// <param name="S"></param>
/// <param name="i"></param>
/// <param name="j"></param>
private void Swap ( byte [ ] S , int i , int j )
{
byte temp = S [ i ] ;
S [ i ] = S [ j ] ;
S [ j ] = temp ;
}
/// <summary>
/// Process AES256
/// </summary>
/// <param name="PCW"></param>
/// <param name="frameType"></param>
/// <param name="voiceSubframe"></param>
/// <returns></returns>
private bool AesProcess ( byte [ ] PCW , FrameType frameType , int voiceSubframe )
{
int offset = 16 ;
switch ( frameType )
{
case FrameType . LDU1 : offset + = 0 ; break ;
case FrameType . LDU2 : offset + = 101 ; break ;
case FrameType . V4_0 : offset + = 7 * voiceSubframe ; break ;
case FrameType . V4_1 : offset + = 7 * ( voiceSubframe + 4 ) ; break ;
case FrameType . V4_2 : offset + = 7 * ( voiceSubframe + 8 ) ; break ;
case FrameType . V4_3 : offset + = 7 * ( voiceSubframe + 12 ) ; break ;
case FrameType . V2 : offset + = 7 * ( voiceSubframe + 16 ) ; break ;
default : return false ;
}
if ( protocol = = ProtocolType . P25Phase1 )
{
offset + = ( aesPosition * 11 ) + 11 + ( aesPosition < 8 ? 0 : 2 ) ;
aesPosition = ( aesPosition + 1 ) % 9 ;
for ( int j = 0 ; j < 11 ; + + j )
{
PCW [ j ] ^ = aesKeystream [ j + offset ] ;
}
}
else if ( protocol = = ProtocolType . P25Phase2 )
{
for ( int j = 0 ; j < 7 ; + + j )
{
PCW [ j ] ^ = aesKeystream [ j + offset ] ;
}
PCW [ 6 ] & = 0x80 ;
}
return true ;
}
/// <summary>
/// Process ADP
/// </summary>
/// <param name="PCW"></param>
/// <param name="frameType"></param>
/// <param name="voiceSubframe"></param>
/// <returns></returns>
private bool AdpProcess ( byte [ ] PCW , FrameType frameType , int voiceSubframe )
{
int offset = 256 ;
j = ( j + permutation [ i ] ) & 0xFF ;
switch ( frameType )
{
case FrameType . LDU1 : offset = 0 ; break ;
case FrameType . LDU2 : offset = 101 ; break ;
case FrameType . V4_0 : offset + = 7 * voiceSubframe ; break ;
case FrameType . V4_1 : offset + = 7 * ( voiceSubframe + 4 ) ; break ;
case FrameType . V4_2 : offset + = 7 * ( voiceSubframe + 8 ) ; break ;
case FrameType . V4_3 : offset + = 7 * ( voiceSubframe + 12 ) ; break ;
case FrameType . V2 : offset + = 7 * ( voiceSubframe + 16 ) ; break ;
default : return false ;
}
// swap permutation[i] and permutation[j]
Swap ( permutation , i , j ) ;
if ( protocol = = ProtocolType . P25Phase1 )
{
offset + = ( adpPosition * 11 ) + 267 + ( adpPosition < 8 ? 0 : 2 ) ;
adpPosition = ( adpPosition + 1 ) % 9 ;
for ( int j = 0 ; j < 11 ; + + j )
{
PCW [ j ] ^ = adpKeystream [ j + offset ] ;
}
// transform byte
adpKeystream [ k ] = permutation [ ( permutation [ i ] + permutation [ j ] ) & 0xFF ] ;
}
else if ( protocol = = ProtocolType . P25Phase2 )
{
for ( int j = 0 ; j < 7 ; + + j )
{
PCW [ j ] ^ = adpKeystream [ j + offset ] ;
}
PCW [ 6 ] & = 0x80 ;
}
return true ;
}
/// <summary>
/// Create AES key stream
/// Create AES keystream.
/// </summary>
private void GenerateA es Keystream( )
private void GenerateAESKeystream ( )
{
if ( ! keys . ContainsKey ( keyId ) )
return ;
byte [ ] key = keys [ keyId ] . Key ;
byte [ ] iv = ExpandM iTo128 ( messageIndicator ) ;
byte [ ] iv = ExpandMIToIV ( messageIndicator ) ;
using ( var aes = Aes . Create ( ) )
{
@ -287,6 +277,48 @@ namespace DVMConsole
}
}
/// <summary>
/// Helper to process IMBE audio using AES-256.
/// </summary>
/// <param name="imbe"></param>
/// <param name="duid"></param>
/// <returns></returns>
private bool AESProcess ( byte [ ] imbe , P25DUID duid )
{
int offset = 16 ;
if ( duid = = P25DUID . LDU2 )
offset + = 101 ;
offset + = ( ksPosition * IMBE_BUF_LEN ) + IMBE_BUF_LEN + ( ksPosition < 8 ? 0 : 2 ) ;
ksPosition = ( ksPosition + 1 ) % 9 ;
for ( int j = 0 ; j < IMBE_BUF_LEN ; + + j )
imbe [ j ] ^ = aesKeystream [ j + offset ] ;
return true ;
}
/// <summary>
/// Helper to process IMBE audio using ARC4.
/// </summary>
/// <param name="imbe"></param>
/// <param name="duid"></param>
/// <returns></returns>
private bool ARC4Process ( byte [ ] imbe , P25DUID duid )
{
int offset = 256 ;
if ( duid ! = P25DUID . LDU2 )
offset + = 101 ;
offset + = ( ksPosition * IMBE_BUF_LEN ) + 267 + ( ksPosition < 8 ? 0 : 2 ) ;
ksPosition = ( ksPosition + 1 ) % 9 ;
for ( int j = 0 ; j < IMBE_BUF_LEN ; + + j )
imbe [ j ] ^ = adpKeystream [ j + offset ] ;
return true ;
}
/// <summary>
/// Cycle P25 LFSR
/// </summary>
@ -350,7 +382,7 @@ namespace DVMConsole
/// <param name="mi"></param>
/// <returns></returns>
/// <exception cref="ArgumentException"></exception>
private static byte [ ] ExpandM iTo128 ( byte [ ] mi )
private static byte [ ] ExpandM IToIV ( byte [ ] mi )
{
if ( mi = = null | | mi . Length < 8 )
throw new ArgumentException ( "MI must be at least 8 bytes long." ) ;
@ -360,16 +392,12 @@ namespace DVMConsole
// Copy first 64 bits of MI into LFSR
ulong lfsr = 0 ;
for ( int i = 0 ; i < 8 ; i + + )
{
lfsr = ( lfsr < < 8 ) | mi [ i ] ;
}
// Use LFSR routine to compute the expansion
ulong overflow = 0 ;
for ( int i = 0 ; i < 64 ; i + + )
{
overflow = ( overflow < < 1 ) | StepP25Lfsr ( ref lfsr ) ;
}
// Copy expansion and LFSR to IV
for ( int i = 7 ; i > = 0 ; i - - )
@ -377,6 +405,7 @@ namespace DVMConsole
iv [ i ] = ( byte ) ( overflow & 0xFF ) ;
overflow > > = 8 ;
}
for ( int i = 15 ; i > = 8 ; i - - )
{
iv [ i ] = ( byte ) ( lfsr & 0xFF ) ;
@ -385,37 +414,5 @@ namespace DVMConsole
return iv ;
}
private class KeyInfo
{
public byte AlgId { get ; }
public byte [ ] Key { get ; }
public KeyInfo ( byte algid , byte [ ] key )
{
AlgId = algid ;
Key = key ;
}
}
public enum ProtocolType
{
Unknown = 0 ,
P25Phase1 ,
P25Phase2
}
public enum FrameType
{
Unknown = 0 ,
LDU1 ,
LDU2 ,
V2 ,
V4_0 ,
V4_1 ,
V4_2 ,
V4_3
}
}
}
} // public class P25Crypto
} // namespace dvmconsole
Bryan Biedenkapp
11 months ago
