CipherText format

This section defines the wire format for M_CipherText and its descendant types.

In a key attestation bundle as described in Key attestation bundle construction, the following fields will use this format:

  • modstatesig

  • kcsig

  • CertKMaKMCbKNSO

  • CertKMaKMCaKFIPSbKNSO

  • CertKREaKRAbKNSO

M_CipherText

This represents a structure with the following fields:

Field Size Format

mech

4 bytes

Little-endian unsigned integer. See M_Mech

data

variable

Depends on field mech. See below.

iv

variable

Depends on field mech. See below.

M_CipherText.data representations

This depends on the value of the mech field, as follows:

Name of mech Value of mech Format of data

Mech_DSAhSHA256

170

M_Mech_DSA_Cipher

Mech_ECDSAhSHA512

187

M_Mech_ECDSA_Cipher

Any supported values of mech not present in the table correspond to an empty (zero-length) data field.

M_CipherText.iv representations

All of the supported values of mech correspond to an empty (zero-length) iv field.

M_Mech_DSA_Cipher

This represents a structure with the following fields:

Field Size Format

r

variable

See M_Bignum

s

variable

See M_Bignum

M_Mech_ECDSA_Cipher

This represents a structure with the following fields:

Field Size Format

r

variable

See M_Bignum

s

variable

See M_Bignum