Key type vectors

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The values of the keys that are calculated while diversification depend on their intended key usage. Therefore, a DK key type vector (KTV) is being introduced to define how to generate or derive (Diversify Directed Key) the intended AES variable-length symmetric key. The KTV is a parameter that defines the rules for the key to be generated or derived. It also contains information that is needed by the HSM to restrict the usage of the key to be generated or derived.

Table 1 defines the layout of the KTV.
Table 1. Key type vector format

Key type vector format in three table columns: offset, length, and description. The final table row contains notes across the table columns.
Offset (bytes) Length (bytes) Description
0 2 Structure version number:
Value
Meaning
X'0000'
Version 0 structure format
2 2 Key type of the key to be derived or generated:
Value
Meaning
X'0000'
MAC
X'0001'
Data encryption (cipher)
X'0003'
PIN encryption
X'0004'
Key wrapping
All other values are reserved and undefined.
4 2 Underlying algorithm:
Value
Meaning
X'0002'
AES
X'0003'
HMAC (only valid with key type indicator MAC, that is, value at offset 2 = X’0000’) – currently not supported.
All other values are reserved and undefined.
6 2 Length of key in bits to be derived or generated:
Value
Meaning
X'0080'
128 (for example, AES-128) – currently not supported.
X'00C0'
192 (for example, AES-192) – currently not supported.
X'0100'
256 (for example, AES-256)
All other values are reserved and undefined.
8 2 Key usage restriction 1 of the key to be derived or generated, based on the key type field (value at offset 2).
For MAC key type (value at offset 2 = X'0000'):
Value
Meaning
X'0001'
Key can derive or generate a CMAC mode key only.
X'0002'
Key can derive or generate an HMAC mode key only – currently not supported.
All other values are reserved and undefined.
For data encryption (cipher) key type (value at offset 2 = X'0001'):
Value
Meaning
X'0000'
Key can derive or generate any mode key – currently not supported.
X'0001'
Key can derive or generate an ECB mode key only – currently not supported.
X'0002'
Key can derive or generate a CBC mode key only.
X'0003'
Key can derive or generate a CTR mode key only – currently not supported.
All other values are reserved and undefined.
For PIN encryption key type (value at offset 2 = X'0003'):
Value
Meaning
X'0000' or X'0002'
Key can derive or generate an ISO-4 format PIN block.
All other values are reserved and undefined.
For key wrap key type (value at offset 2 = X'0004'):
Value
Meaning
X'0001'
Key can derive or generate a VARDRV-D key only, where "D" stands for DK Key Block Protection according to ISO TC 68/SC 2 Nxxxx, 2016-08-17, ISO DIS 20038 to wrap AES and TDES keys in CBC mode.
For all other key types not listed above:
Value
Meaning
X'0000'
No key usage restriction 1.
All other values are reserved and undefined.
10 2 Key usage restriction 2 of the key to be derived or generated, depending on the key type (offset 2) and key usage restriction 1 (offset 8):
For MAC key type and HMAC mode (value at offset 2 = X'0000' and offset 8 = X'0001'):
Value
Meaning
X'0002'
SHA-256
X'0003'
SHA-384
X'0004'
SHA-512
All other values are reserved and undefined.
Key-wrap key type and VARDRV-D mode (value at offset 2 = X'0004' and offset 8 = X'0001'):
Value
Meaning
X'0080'
Maximum key length of the protected keys is 128 bits – currently not supported.
X'00C0'
Maximum key length of the protected keys is 192 bits – currently not supported.
X'0100'
Maximum key length of the protected keys is 256 bits.
All other values are reserved and undefined.
For all other values at offset 2 and offset 8:
Value
Meaning
X'0000'
Undefined.
All other values are reserved and undefined.
For all other key types and key usage restriction 1 combinations that are not listed above:
Value
Meaning
X'0000'
No key usage restriction 2.
All other values are reserved and undefined.
12 3 Reserved, must be binary zeros.
15 1 Key direction variant indicator.

Diversifies the key to be derived or generated depending on the permitted use of direction.

The HSM has to restrict the usage of the key depending on this value and the type of entity (A or B) which is an additional parameter in the process of deriving or generating the key.

Thus this value affects a key usage attribute of the key to be derived or generated.
Value
Meaning
X'00'
A↔B (undirected use of key). This is defined but unsupported.
X'01'
A→B (A active, B passive use of key).
X'10'
A←B or equivalent (A passive, B active use of key).
X'FF'
System is to determine key direction from entity usage of the KDKGENKY and rule array keywords.
KDK-A + GENERATE rule array keyword
Direction set to X'01' (A→B).
KDK-B + GENERATE rule array keyword
Direction set to X'10' (A←B).
KDK-A + DERIVE rule array keyword
Direction set to X'10' (A←B).
KDK-B + DERIVE rule array keyword
Direction set to X'01' (A→B).
All other values are reserved and undefined.
Note:
  1. All numbers are in big endian format.
  2. In addition to a key type that can be requested, there is also the option to return the key wrapped using the key wrapping method specified in ISO 20038. ISO 20038 defines a key-wrapping method for banking and related financial services.

For each of the four key types that are defined at KTV offset 2 (MAC, data encryption, PIN encryption, and key wrapping), two KTVs are defined. The only difference between them is the key direction variant indicator (KTV offset 15). Either entity Type A is active and Type B is passive (A→B), or Type B is active and Type A is passive (A←B).

Table 2. Summary of KTV tables

The second and third header column of this table are subdivided into two columns each: KTM vector and reference to table with details.
Key type of key to be derived A→B (A active) A←B (B active)
MAC (generate/verify) KTVM1 See Table 3. KTVM2 See Table 4.
Data encryption (encipher/decipher) KTVC1 See Table 5. KTVC2 See Table 6.
PIN encryption (encipher/decipher) KTVP1 See Table 9. KTVP2 See Table 10.
Key wrapping (wrap/unwrap) KTVW1 See Table 11. KTVW2 See Table 12.
Table 3. KTV for MAC generate/verify, Type A active and Type B passive

The final table row extends across the table columns and specifies the KTV.
Version (offset 0) Key type indicator (offset 2) Algorithm indicator (offset 4) Key length (offset 6) Key usage indicator 1 (offset 8) Key usage restriction 2 (offset 10) RFU (offset 12) Key direction variant indicator (offset 15)
0 MAC AES AES-256 CMAC 'else' - A→B
00 00 00 00 00 02 01 00 00 01 00 00 00 00 00 01
KTVM1 = X'00 00 00 00 00 02 01 00 00 01 00 00 00 00 00 01'
Table 4. KTV for MAC generate/verify, Type B active and Type A passive

The final table row extends across the table columns and specifies the KTV.
Version (offset 0) Key type indicator (offset 2) Algorithm indicator (offset 4) Key length (offset 6) Key usage indicator 1 (offset 8) Key usage restriction 2 (offset 10) RFU (offset 12) Key direction variant indicator (offset 15)
0 MAC AES AES-256 CMAC 'else' - A←B
00 00 00 00 00 02 01 00 00 01 00 00 00 00 00 10
KTVM2 = X'00 00 00 00 00 02 01 00 00 01 00 00 00 00 00 10'
Table 5. KTV for data encryption (cipher), Type A active and Type B passive

The final table row extends across the table columns and specifies the KTV.
Version (offset 0) Key type indicator (offset 2) Algorithm indicator (offset 4) Key length (offset 6) Key usage indicator 1 (offset 8) Key usage restriction 2 (offset 10) RFU (offset 12) Key direction variant indicator (offset 15)
0 Cipher AES AES-256 CBC 'else' - A→B
00 00 00 01 00 02 01 00 00 02 00 00 00 00 00 01
KTVC1 = X'00 00 00 01 00 02 01 00 00 02 00 00 00 00 00 01'
Table 6. KTV for data encryption (cipher), Type B active and Type A passive

The final table row extends across the table columns and specifies the KTV.
Version (offset 0) Key type indicator (offset 2) Algorithm indicator (offset 4) Key length (offset 6) Key usage indicator 1 (offset 8) Key usage restriction 2 (offset 10) RFU (offset 12) Key direction variant indicator (offset 15)
0 Cipher AES AES-256 CBC 'else' - A←B
00 00 00 01 00 02 01 00 00 02 00 00 00 00 00 10
KTVC2 = X'00 00 00 01 00 02 01 00 00 02 00 00 00 00 00 10'

For PIN encryption key type, the key usage indicator 1 (offset 8) for ISO-4 format can have the value of '0000' or '0002' for a pair of KTVs. The caller is not allowed to mix pairs of KTVs because the KTV is used as the IV in the key creating process. This is the responsibility of the caller of the service.

KTV pair for PIN encryption key type with key usage indicator 1 with '0000' value.

Table 7. KTV for PIN encryption, Type A active and Type B passive - with key usage indicator 1 with '0000' value.

The final table row extends across the table columns and specifies the KTV.
Version (offset 0) Key type indicator (offset 2) Algorithm indicator (offset 4) Key length (offset 6) Key usage indicator 1 (offset 8) Key usage restriction 2 (offset 10) RFU (offset 12) Key direction variant indicator (offset 15)
0 PIN-Enc AES AES-256 ISO-4 'else' - A→B
00 00 00 03 00 02 01 00 00 00 00 00 00 00 00 01
KTVP1 = X'X'00 00 00 03 00 02 01 00 00 00 00 00 00 00 00 01''
Table 8. KTV for PIN encryption, Type B active and Type A passive - with key usage indicator 1 with '0000' value.

The final table row extends across the table columns and specifies the KTV.
Version (offset 0) Key type indicator (offset 2) Algorithm indicator (offset 4) Key length (offset 6) Key usage indicator 1 (offset 8) Key usage restriction 2 (offset 10) RFU (offset 12) Key direction variant indicator (offset 15)
0 PIN-Enc AES AES-256 ISO-4 'else' - A←B
00 00 00 03 00 02 01 00 00 00 00 00 00 00 00 10
KTVP2 = X'00 00 00 03 00 02 01 00 00 00 00 00 00 00 00 10'

KTV pair for PIN encryption key type with key usage indicator 1 with '0002' value.

Table 9. KTV for PIN encryption, Type A active and Type B passive - with key usage indicator 1 with '0002' value.

The final table row extends across the table columns and specifies the KTV.
Version (offset 0) Key type indicator (offset 2) Algorithm indicator (offset 4) Key length (offset 6) Key usage indicator 1 (offset 8) Key usage restriction 2 (offset 10) RFU (offset 12) Key direction variant indicator (offset 15)
0 PIN-Enc AES AES-256 ISO-4 'else' - A→B
00 00 00 03 00 02 01 00 00 02 00 00 00 00 00 01
KTVP3 = X'00 00 00 03 00 02 01 00 00 02 00 00 00 00 00 01'
Table 10. KTV for PIN encryption, Type B active and Type A passive - with key usage indicator 1 with '0002' value.

The final table row extends across the table columns and specifies the KTV.
Version (offset 0) Key type indicator (offset 2) Algorithm indicator (offset 4) Key length (offset 6) Key usage indicator 1 (offset 8) Key usage restriction 2 (offset 10) RFU (offset 12) Key direction variant indicator (offset 15)
0 PIN-Enc AES AES-256 ISO-4 'else' - A←B
00 00 00 03 00 02 01 00 00 02 00 00 00 00 00 10
KTVP4 = X'00 00 00 03 00 02 01 00 00 02 00 00 00 00 00 10'
Entity Type A must use an AES EXPORTER key with usage of EXPTT31D. Entity Type B must use an IMPORTER key with usage of IMPTT31D. Key wrapping with key block protection (ISO TC 68/SC 2 Nxxxx, 2016-08-17, ISO DIS 20038).
Table 11. KTV for key wrapping, Type A active and Type B passive

The final table row extends across the table columns and specifies the KTV.
Version (offset 0) Key type indicator (offset 2) Algorithm indicator (offset 4) Key length (offset 6) Key usage indicator 1 (offset 8) Key usage restriction 2 (offset 10) RFU (offset 12) Key direction variant indicator (offset 15)
0 Key wrap AES AES-256 VARDRV-D Maximum bit length of the protected keys - A→B
00 00 00 04 00 02 01 00 00 01 01 00 00 00 00 01
KTVW1 = X'00 00 00 04 00 02 01 00 00 01 01 00 00 00 00 01'
Entity Type B must use an AES EXPORTER key with usage of EXPTT31D. Entity Type A must use an IMPORTER key with usage of IMPTT31D.
Table 12. KTV for key wrapping, Type B active and Type A passive

The final table row extends across the table columns and specifies the KTV.
Version (offset 0) Key type indicator (offset 2) Algorithm indicator (offset 4) Key length (offset 6) Key usage indicator 1 (offset 8) Key usage restriction 2 (offset 10) RFU (offset 12) Key direction variant indicator (offset 15)
0 Key wrap AES AES-256 VARDRV-D Maximum bit length of the protected keys - A←B
00 00 00 04 00 02 01 00 00 01 01 00 00 00 00 10
KTVW2 = X'00 00 00 04 00 02 01 00 00 01 01 00 00 00 00 10'
Table 13 shows the key usage mapping of the output key from Diversify Directed Key, based on the KTV input to that verb.
Table 13. KTV to CCA key type and usage mapping

This table contains eight columns: KTV key type, KTV key direction variant indicator, Algorithm (offset 4 = X’0002’), KDKGENKY KUF1 HOB (entity type), CCA AES key type, KUF1 HOB, KUF2 HOB. Entries in the first column span 4 rows, entries in the 3rd, forth, and eighth column span 2 rows.
KTV key type KTV KTV key direction variant indicator Algorithm (offset 4 = X’0002’) KDKGENKY KUF1 HOB (entity type) CCA AES key type KUF1 HOB KUF2 HOB
MAC (offset 2 = X’0000’) KTVM1

A→B
(offset 15
= X'01')

 AES A MAC GENONLY CMAC
KTVM2 B MAC VERIFY
KTVM2

A←B
(offset 15
= X'10')

 AES A MAC VERIFY CMAC
KTVM1 B MAC GENONLY
Cipher (offset 2 = X’0001’) KTVC1

A→B
(offset 15
= X'01')

 AES A CIPHER ENCRYPT CBC
KTVC2 B CIPHER DECRYPT
KTVC2

A←B
(offset 15
= X'10')

 AES A CIPHER DECRYPT CBC
KTVC1 B CIPHER ENCRYPT
PIN encryption (offset 2 = X'0003') KTVP1

A→B
(offset 15
= X’01’)

 AES A PINPROT ENCRYPT CBC
KTVP2 B PINPROT DECRYPT
KTVP2

A←B
(offset 15
= X’10’)

 AES A PINPROT DECRYPT CBC
KTVP1 B PINPROT ENCRYPT
Key wrapping (offset 2 = X’0004’) KTVW1

A→B
(offset 15
= X’01’)

 AES A EXPORTER EXPTT31D N/A
KTVW2 B IMPORTER IMPTT31D
KTVW2

A←B
(KTV offset
15 = X’10’)

 AES A IMPORTER IMPTT31D N/A
KTVW1 B EXPORTER EXPTT31D