6.4.4 TCDUGeneration function for key change tokens 用于密钥更改令牌的TCDU生成函数
This is the transfer function from the APDU to the TCDU (see Figure 8) and is applicable to all key change tokens.
这是从APDU到TCDU的传输函数（参见图8），适用于所有的密钥更改令牌。
A separate TCDU is produced for each key change token in the set.
为集合中的每个密钥更改令牌生成一个单独的TCDU。
Note that the APDU has to present two sets of data for the PANBlock and CONTROLBlock:one set with the new data for the new DecoderKey and a second set with the current data for the current DecoderKey. The DKGA value is the same for both sets.
注意，APDU必须为PANBlock和CONTROLBlock提供两组数据：一组是用于新解码器键的新数据，另一组是用于当前解码器键的当前数据。两个集合的DKGA值相同。
NOTE 1 The data elements in the APDU are defined in 6.1 .1 .
注1:APDU中的数据元素定义在6.1 .1中。
NOTE 2 The data elements in the TCDU are defined in each part of the IEC 62055-5x series physical layer protocol standard relevant to the specific TCT of interest.
注2:TCDU中的数据元素定义在与具体TCT相关的IEC 62055-5x系列物理层协议标准的每个部分中。
The transfer function is outlined as follows:传递函数如下：
• the new DecoderKey is generated using the new values of SGC, KRN, KT, TI, IIN, DRN,DKGA, EA and BDT. The specific algorithm to use is in accordance with the value of DKGA in the APDU;
使用SGC、KRN、KT、TI、IIN、DRN、DKGA、EA和BDT的新值生成新的解码器密钥。具体使用的算法按照APDU中的DKGA值；
• the resultant new DecoderKey value 32-bit portion is then used to replace the NKHO,NKMO1 , NKMO2 or NKLO field of the key change token (see 6.2.7 and 6.2.8) as presented by the APDU;
生成的新DecoderKey值的32位部分然后用于替换密钥更改令牌的NKHO、NKMO1、NKMO2或NKLO字段（见APDU提供的6.2.7和6.2.8）；
• the 2 Class bits are removed from the 66-bit token to yield a 64-bit result, which is then presented to the encryption algorithm as its DataBlock input. The specific encryption algorithm to use is in accordance with the EA code in the APDU;
从66位的令牌中去掉2个类别位，得到64位的结果，然后将其作为数据块的输入提供给加密算法。具体使用的加密算法按照APDU中的EA代码；
• the KeyBlock input for the encryption algorithm is obtained from the decoder key generation algorithm, which generates the current DecoderKey using the current values of SGC, KRN, KT, TI, IIN, DRN DKGA, EA and BDT from the APDU as indicated. The specific decoder key generation algorithm to use is in accordance with the value of DKGA in the APDU;
加密算法的密钥块输入由解码器密钥生成算法得到，解码器密钥生成算法使用APDU中SGC、KRN、KT、TI、IIN、DRN DKGA、EA和BDT的当前值生成当前解码器密钥。具体使用的解码器密钥生成算法根据APDU中的DKGA值；
• after encryption, the 2 Class bits are again re-inserted into the 64-bit number in accordance with the method defined in 6.4.2 to yield a 66-bit result, which is populated into the TokenData field of the TCDU in accordance with the particular definition in the relevant physical layer protocol standard;
加密后，按照6.4.2中定义的方法将这2类比特重新插入到64位数字中，得到66位结果，并按照相关物理层协议标准的特定定义填充到TCDU的TokenData字段中；
• similarly the TCT, IDRecord and PRNRecord data elements from the APDU are transferred to the TCDU as indicated, into the appropriate fields of the TCDU in accordance with the particular definition in the relevant physical layer protocol standard.
类似地，APDU的TCT、IDRecord和PRNRecord数据元素根据相关物理层协议标准的特定定义，按指示传输到TCDU的适当字段。
