2.2.2.1 PUBLIC_KEY_BLOB
The PUBLIC_KEY_BLOB message is used to store information about RSA key exchange public keys and RSA signature public keys. It is used during secure session negotiation.
The syntax of the PUBLIC_KEY_BLOB message is represented by the following diagram.
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PublicKeyBlobDataLength |
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Reserved0 |
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Reserved |
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AlgID |
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Magic |
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BitLen |
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PubExp |
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Modulus (variable) |
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PublicKeyBlobDataLength (4 bytes): A 32-bit unsigned integer. This field contains the total length of the PUBLIC_KEY_BLOB instance excluding the PublicKeyBlobDataLength and Reserved0 fields.
Reserved0 (4 bytes): A 32-bit unsigned integer. This field MUST be set to 0x0.
Type (1 byte): An 8-bit unsigned integer. This field MUST be set to 0x6. This indicates that the public key is transferred.
Version (1 byte): An 8-bit unsigned integer. This field MUST be set to 0x2.
Reserved (2 bytes): A 16-bit unsigned integer. This field MUST be set to 0x0.
AlgID (4 bytes): A 32-bit unsigned integer. This field is set to the CALG_RSA_KEYX value if the key exchange public key is stored in the BLOB or the CALG_RSA_SIGN value if the signature public key is stored.
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Value
Meaning
CALG_RSA_KEYX
0x0000A400
RSA public key exchange algorithm
CALG_RSA_SIGN
0x00002400
RSA public key signature algorithm
Magic (4 bytes): A 32-bit unsigned integer. This field MUST be set to 0x31415352. The value can be interpreted as the ASCII-encoded string "RSA1".
BitLen (4 bytes): A 32-bit unsigned integer that specifies the size of the public key in bits. This field MUST be set to 0x200 (512) because the 512 (=0x200) bit RSA key is used.
PubExp (4 bytes): A 32-bit unsigned integer that is a public exponent, as specified in [RFC8017].
Modulus (variable): A variable-length array of bytes that stores the RSA public key. The size, in bytes, of the Modulus field is BitLen/8.