AES PINPROT, PINCALC, and PINPRW variable-length symmetric key token

Header

Token identifier:

Value

Meaning

X'01'

Internal key-token (encrypted key is wrapped with the master key or there is no payload).

X'02'

External key-token (encrypted payload is wrapped with a transport key or there is no payload). A transport key can be a key-encrypting key or an RSA public-key.

All unused values are reserved and undefined.

Reserved, binary zero.

Length in bytes of the overall token structure:

46 + (2 * kuf) + (2 * kmf) + kl + iead + uad + ((pl + 7) / 8)

Key token

Minimum token length

Skeleton

46 + (2 * 3) + (2 * 3) + 0 + 0 + 0 + 0 = 58

Encrypted V1 payload

46 + (2 * 3) + (2 * 3) + 0 + 0 + 0 + ((640 + 7) / 8) = 138

Key token

Maximum token length

External*

46 + (2 * 3) + (2 * 3) + 64 + 0 + 255 + ((8192 + 7) / 8) = 1401

Internal

46 + (2 * 3) + (2 * 3) + 64 + 0 + 255 + ((640 + 7) / 8) = 457

*This assumes a PKOAEP2 key-wrapping method using a 8192-bit RSA transport key.

Token version number (identifies the format of this key token):

Value

Meaning

X'05'

Version 5 format of the key token (variable-length symmetric key-token)

Reserved, binary zero.

End of header

Wrapping information section (all data related to wrapping the key)

Key material state:

Value

Meaning

X'00'

No key is present. This is called a skeleton key-token. The key token is external or internal.

X'02'

Key is wrapped with a transport key. When the encrypted section key-wrapping method is AESKW (value at offset 26 is X'02'), the transport key is an AES key-encrypting key. When it is PKOAEP2 (value at offset 26 is X'03'), the transport key is an RSA public-key. The key token is external.

X'03'

Key is wrapped with the AES master-key. The encrypted section key-wrapping method is AESKW. The key token is internal.

All unused values are reserved and undefined.

Key verification pattern (KVP) type:

Value

Meaning

X'00'

No KVP (no key present or key is wrapped with an RSA public-key). The key token is external or internal.

X'01'

AESMK (8 leftmost bytes of SHA-256 hash: X'01 ∥ clear AES MK). The key token is internal.

X'02'

KEK (8 leftmost bytes of SHA-256 hash: X'01 ∥ clear KEK). The key token is external.

All unused values are reserved and undefined.

KVP (value depends on value of key material state, that is, the value at offset 8):

Value at offset 8

Value of KVP

X'00'

The key-material state is no key present. The field should be filled with binary zeros. The key token is external or internal.

X'02'

The key material state is the key is wrapped with a transport key. The value of the KVP depends on the value of the encrypted section key-wrapping method:

• When the key-wrapping method is AESKW (value at offset 26 is X'02'), the field contains the KVP of the key-encrypting key used to wrap the key. The 8-byte KEK KVP is left-aligned in the field and padded on the right low-order bytes with binary zeros.
• When the key-wrapping method is PKOAEP2 (value at offset 26 is X'03'), the value should be filled with binary zeros. The encoded message, which contains the key, is wrapped with an RSA public-key.

The key token is external.

X'03'

The key-material state is the key is wrapped with the AES master-key. The field contains the MKVP of the AES master-key used to wrap the key. The 8-byte MKVP is left-aligned in the field and padded on the right low-order bytes with binary zeros. The key token is internal.

Encrypted section key-wrapping method (how data in the encrypted section is protected):

Value

Meaning

X'00'

No key-wrapping method (no key present). The key token is external or internal.

X'02'

AESKW (ANS X9.102). The key token is external with a key wrapped by an AES key-encrypting key, or the key token is internal with a key wrapped by the AES master-key.

X'03'

PKOAEP2. Message M, which contains the key, is encoded using the RSAES-OAEP scheme of the RSA PKCS #1 v2.1 standard. The encoded message (EM) is produced using the given hash algorithm by encoding message M using the Bellare and Rogaway Optimal Asymmetric Encryption Padding (OAEP) method for encoding messages. For PKAOEP2, M is defined as follows:

M = [32 bytes: hAD] ∥ [2 bytes: bit length of the clear key] ∥ [clear key]

where hAD is the message digest of the associated data, and is calculated using the SHA-256 algorithm on the data starting at offset 30 for the length in bytes of all the associated data for the key token (length value at offset 32).

EM is wrapped with an RSA public-key. The key token is external.

All unused values are reserved and undefined.

Hash algorithm used for wrapping key or encoding message. Meaning depends on whether the encrypted section key-wrapping method (value at offset 26) is no key-wrapping method, AESKW, or PKOAEP2:

No key-wrapping method (value at offset 26 is X'00')

Hash algorithm used for wrapping key when encrypted section key-wrapping method is no key-wrapping method:

Value

Meaning

X'00'

No hash (no key present)

All unused values are reserved and undefined. The key token is external or internal.

AESKW key-wrapping method (value at offset 26 is X'02')

Hash algorithm used for wrapping key when encrypted section key-wrapping method is AESKW. The value indicates the algorithm used to calculate the message digest of the associated data. The message digest is included in the wrapped payload and is calculated starting at offset 30 for the length in bytes of all the associated data for the key token (length value at offset 32).

Value

Meaning

X'02'

SHA-256

All unused values are reserved and undefined. The key token is external or internal.

PKOAEP2 key-wrapping method (value at offset 26 is X'03')

Hash algorithm used for encoding message when encrypted section key-wrapping method is PKOAEP2. The value indicates the given hash algorithm used for encoding message M using the RSAES-OAEP scheme of the RSA PKCS #1 v2.1 standard.

Value

Meaning

X'01'

SHA-1

X'02'

SHA-256

X'04'

SHA-384

X'08'

SHA-512

All unused values are reserved and undefined. The key token is external.

Payload format version (identifies format of the payload):

Value

Meaning

X'01'

V1 payload (V0PYLD). The payload format depends on the encrypted section key-wrapping method (value at offset 26):

Value at offset 26

Meaning

X'00'

There is no key-wrapping method. When no key is present, there is no payload. The key token is external or internal.

X'02'

The key-wrapping method is AESKW and the payload is fixed length based on the maximum possible key size of the algorithm for the key. The key is padded with random data to the size of the largest key for that algorithm. This helps to deter attacks on keys known to be weaker. The key length cannot be inferred by the size of the payload. The key token is external or internal.

X'03'

The key-wrapping method is PKOAEP2 and the payload length is equal to the modulus size in bits of the RSA transport key used to wrap the encoded message. The key token is external. When the external key is exported, the internal target key will have the same V1 payload format.

All unused values are reserved and undefined.

Reserved, binary zero.

End of wrapping information section

AESKW or PKOAEP2 components: (1) associated data section and (2) optional wrapped AESKW formatted payload or wrapped PKOAEP2 encoded payload (no payload if no key present)

Associated data section

Associated data section version:

Value

Meaning

X'01'

Version 1 format of associated data

Reserved, binary zero.

Length in bytes of all the associated data for the key token: 16 - 347.

Length in bytes of the optional key label (kl): 0 or 64.

Length in bytes of the optional IBM extended associated data (iead): 0.

Length in bytes of the optional user-definable associated data (uad): 0 - 255.

Reserved, binary zero.

Length in bits of the wrapped payload (pl): 0, 512 - 4096.

• For no key-wrapping method (no key present), pl is 0.
• For PKOAEP2 encoded payloads, pl is the length in bits of the modulus size of the RSA key used to wrap the payload. This can be 512 - 4096.
• For an AESKW formatted payload, pl is based on the key size of the algorithm type and the payload format version:

  AES algorithm (value at offset 41 is X'02')

  • An AES key can have a length of 16, 24, or 32 bytes (128, 192, or 256 bits). The following table shows the payload length for a given AES key size and payload format:

                          Bit length of            Bit length of
                          V0 payload (value at     V1 payload (value at
  AES key size            offset 28 is X'00')      offset 28 is X'01')
  16 bytes (128 bits)     Not applicable           640
  24 bytes (192 bits)     Not applicable           640
  32 bytes (256 bits)     Not applicable           640

Reserved, binary zero.

Algorithm type (algorithm for which the key can be used):

Value

Meaning

X'02'

AES

All unused values are reserved and undefined.

Key type (general class of the key):

All unused values are reserved and undefined.

Key usage fields count (kuf): 3. For PINPROT: 3, if value at offset 50 = X’01’ (DK enabled), or 4, if value at offset 50 = X’00’ (no field format specification).

Key-usage field information defines restrictions on the use of the key.

For key type PINPROT, see AES PINPROT Key Token Build2 keywords (Figure 8).

For key type PINCALC, see AES PINCALC Key Token Build2 keywords (Figure 7).

For key type PINPRW, see AES PINPRW Key Token Build2 keywords (Figure 9).

Each key-usage field is 2 bytes in length. The value in this field indicates how many 2-byte key usage fields follow.

Key-usage field 1, high-order byte. The meaning is determined by the key type (value at offset 42). The key type can be PINPROT, PINCALC, or PINPRW:

PINPROT (value at offset 42 is X'0005')

Encryption operation:

Value

Meaning

B'11xx xxxx'

Undefined or not used.

B'10xx xxxx'

Key can be used for encryption; key cannot be used for decryption (ENCRYPT).

B'01xx xxxx'

Key cannot be used for encryption; key can be used for decryption (DECRYPT).

B'00xx xxxx'

Undefined or not used.

All unused bits are reserved and must be zero.

PINCALC (value at offset 42 is X'0006')

MAC operation:

Value

Meaning

B'1xxx xxxx'

Key can only be used for generate (GENONLY).

B'0xxx xxxx'

Undefined or not used.

All unused bits are reserved and must be zero.

PINPRW (value at offset 42 is X'0007')

MAC operation:

Value

Meaning

B'11xx xxxx'

Undefined or not used.

B'10xx xxxx'

Key can be used for generate; key cannot be used for verify (GENONLY).

B'01xx xxxx'

Key cannot be used for generate; key can be used for verify (VERIFY).

B'00xx xxxx'

Undefined or not used.

All unused bits are reserved and must be zero.

Key-usage field 1, low-order byte (user-defined extension control).

Key-usage field 2, high-order byte. The meaning is determined by the key type (value at offset 42). The key type can be PINPROT, PINCALC, or PINPRW:

PINPROT (value at offset 42 is X'0005')

Encryption mode:

Value

Meaning

X'00'

Key can be used for Cipher Block Chaining (CBC).

All unused values are reserved and undefined.

PINCALC (value at offset 42 is X'0006')

Encryption mode:

Value

Meaning

X'00'

Key can be used for Cipher Block Chaining (CBC).

All unused values are reserved and undefined.

PINPRW (value at offset 42 is X'0007')

MAC mode:

Value

Meaning

X'01'

CMAC mode (NIST SP 800-38B)

All unused values are reserved and undefined.

Key-usage field 2, low-order byte. The meaning is determined by the key type (value at offset 42). The key type can be PINPROT, PINCALC, or PINPRW:

PINPROT (value at offset 42 is X'0005'):

Inbound key (value at offset 45 is B'01xx xxxx')

• B’xxx1 xxxx’ Key can be used to verify an encrypted PIN (EPINVER).
• B’xxx0 xxxx’ Key cannot be used to verify an encrypted PIN.
• B’xxxx 1xxx’ Key can be used to generate an alternate clear PIN (CPINGENA).
• B’xxxx 0xxx’ Key cannot be used to generate an alternate clear PIN.
• B’xxxx x1xx’ Key can be used to translate an encrypted PIN (PINXLATE).
• B’xxxx x0xx’ Key cannot be used to translate an encrypted PIN.
• B’xxxx xx1x’ Key can be used to reformat an encrypted PIN (REFORMAT).
• B’xxxx xx0x’ Key cannot be used to reformat an encrypted PIN.
• B’xxxx xxx1’ Key can be used to restrictively reformat an ISO-4 encrypted PIN to an ISO-1 encrypted PIN (RFMT4TO1).
• B’xxxx xxx0’ Key cannot be used to reformat an ISO-4 encrypted PIN to an ISO-1 encrypted PIN.

All unused bits are reserved and must be zero.

Outbound key (value at offset 45 is B'10xx xxxx')

• B’xx1x xxxx’ Key can be used to encrypt a clear PIN (CPINENC).
• B’xx0x xxxx’ Key cannot be used to encrypt a clear PIN.
• B’xxx1 xxxx’ Key can be used to generate an encrypted PIN (EPINGEN).
• B’xxx0 xxxx’ Key cannot be used to generate an encrypted PIN.
• B’xxxx x1xx’ Key can be used to translate an encrypted PIN (PINXLATE).
• B’xxxx x0xx’ Key cannot be used to translate an encrypted PIN.
• B’xxxx xx1x’ Key can be used to reformat an encrypted PIN (REFORMAT).
• B’xxxx xx0x’ Key cannot be used to reformat an encrypted PIN.
• B’xxxx xxx1’ Key can be used to restrictively reformat an ISO-1 encrypted PIN to an ISO-4 encrypted PIN (RFMT1TO4).
• B’xxxx xxx0’ Key cannot be used to restrictively reformat an ISO-1 encrypted PIN to an ISO-4 encrypted PIN.

All unused bits are reserved and must be zero.

PINCALC (value at offset 42 is X'0006')

All bits are reserved and must be zero.

PINPRW (value at offset 42 is X'0007')

All bits are reserved and must be zero.

Key-usage field 3, high-order byte. The meaning is determined by the field format identifier (value at offset 50). Currently the only field format identifier is DK enabled:

DK enabled (value at offset 50 is X'01')

                  Key type (value at offset 42)
Value  Meaning    PINPROT     PINCALC     PINPRW
X'01'  PIN OP     Valid       Valid       Valid
       (DKPINOP)
X'02'  PIN OPP    Valid       Undefined   Undefined
       (DKPINOPP)
X'03'  PIN AD1    Valid       Undefined   Undefined
       (DKPINAD1)

All unused values are reserved and undefined.

Key-usage field 3, low-order byte (field format identifier). Identifies the format of key-usage field 3, high-order byte (value at offset 49):

Value

Meaning

X'01'

DK enabled (set when DKPINOP, DKPINOPP, or DKPINAD1 keyword is used)

All unused values are reserved and undefined.

Key management fields count (kmf): 3. Key-management field information describes how the data is to be managed or helps with management of the key material.

For key type PINPROT, see AES PINPROT Key Token Build2 keywords (Figure 8).

For key type PINCALC, see AES PINCALC Key Token Build2 keywords (Figure 7).

For key type PINPRW, see AES PINPRW Key Token Build2 keywords (Figure 9).

Each key-management field is 2 bytes in length. The value in this field indicates how many 2-byte key management fields follow.

Key-management field 1, high-order byte (symmetric-key export control).

Key-management field 1, low-order byte (export control by algorithm).

Key-management field 2, high-order byte (key completeness).

Key-management field 2, low-order byte (security history).

Key-management field 3, high-order byte (pedigree original).

Key-management field 3, low-order byte (pedigree current).

Optional key label.

Optional IBM extended associated data (unused).

Optional user-defined associated data.

End of associated data section

Optional wrapped AESKW formatted payload or wrapped PKOAEP2 encoded payload (no payload if no key present)

058 + kl + iead + uad

(pl + 7) / 8

Contents of payload (pl is in bits) depending on the encrypted section key-wrapping method (value at offset 26):

M = [32 bytes: hAD] ∥ [2 bytes: bit length of the clear key] ∥ [clear key]

where hAD is the message digest of the associated data, and is calculated using the SHA-256 algorithm starting at offset 30 for the length in bytes of all the associated data for the key token (length value at offset 32). The encoded message is wrapped with an RSA public-key according to the standard. The key token is external.

End of optional wrapped AESKW formatted payload or wrapped PKAOEP2 encoded payload

End of AESKW or PKOAEP2 components