RSA private external key token

Read the contained information about the basic structure of RSA private external key tokens.

An RSA private external key token contains the following sections:

a required PKA token header starting with the token identifier X'1E'
a required RSA private key section, one of those shown in Table 1, each starting with a certain section identifiers
a required RSA public key section, starting with the section identifier X'04'
an optional private key name section, starting with the section identifier X'10'.

Table 1 presents the basic record format of an RSA private external key token. All length fields are in binary. All binary fields (exponents, lengths, and so on) are stored with the high-order byte first (big-endian format). All binary fields (exponents, modulus, and so on) in the private sections of tokens are right-aligned and padded with zeros to the left.

Table 1. RSA private external key token basic record format
Offset (decimal)	Length (bytes)	Description
*Token Header* (Required)
000	001	Token identifier. X'1E' indicates an external token. The private key is either in cleartext or enciphered with a transport key-encrypting key.
001	001	Version, X'00'.
002	002	Length of the key token structure.
004	004	Ignored. Should be zero.
*RSA Private Key Section* (Required) See the following sections: RSA private key token, 1024-bit Modulus-Exponent RSA private key token, 1024-bit Modulus-Exponent format with OPK section RSA private key token, 4096-bit Modulus-Exponent RSA private key, 4096-bit Modulus-Exponent format with AES encrypted OPK section RSA private key, 4096-bit Chinese Remainder Theorem with OPK RSA private key, 4096-bit Chinese Remainder Theorem format with AES encrypted OPK section
*RSA Public Key Section* (Required)
000	001	X'04', section identifier, RSA public key.
001	001	X'00', version.
002	002	Section length, 12 + xxx.
004	002	Reserved field.
006	002	RSA public key exponent field length in bytes, xxx.
008	002	Public key modulus length in bits.
010	002	RSA public key modulus field length in bytes, which is zero for a private token. Note: In an RSA private key token, this field should be zero. The RSA private key section contains the modulus.
012	xxx	Public key exponent, e (this is generally a 1, 3, or 64 - 256-byte quantity). e must be odd and 1 < e < n. (Frequently, the value of e is 2¹⁶ + 1 (= 65,537). Note: You can import an RSA public key having an exponent valued to two (2). Such a public key can correctly validate an ISO 9796-1 digital signature. However, the current product implementation does not generate an RSA key with a public exponent valued to two (a Rabin key).
*Private Key Name* (Optional)
000	001	X'10', section identifier, private key name.
001	001	X'00', version.
002	002	Section length, X'0044' (68 decimal).
004	064	Private key name (in ASCII), left-aligned, padded with space characters (X'20'). An access control system can use the private key name to verify the calling application is entitled to use the key. When generating an RSA retained private key, the name supplied in this part of the skeleton key-token is subsequently used in the coprocessor to locate the retained key.