Kyle Isom
115f23a3ea
Vendor dependencies and expose control program binaries via nix build. Uses nixpkgs-unstable for Go 1.26 support. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
41 lines
1.3 KiB
Go
41 lines
1.3 KiB
Go
package tpm2
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import (
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"io"
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)
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var (
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labelIdentity = "IDENTITY"
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)
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// CreateCredential creates an encrypted secret that can be recovered using ActivateCredential as part of a key-attestation flow.
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func CreateCredential(rand io.Reader, pub LabeledEncapsulationKey, name []byte, credentialValue []byte) (idObject []byte, encSecret []byte, err error) {
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secret, ciphertext, err := pub.Encapsulate(rand, labelIdentity)
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if err != nil {
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return nil, nil, err
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}
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// Marshal the credentialValue as a TPM2B_DIGEST before encrypting it.
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// See Part 1, "Credential Protection", and Part 2, "TPMS_ID_OBJECT".
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credential2B := Marshal(TPM2BDigest{Buffer: credentialValue})
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// Encrypt the credentialValue as encIdentity.
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encIdentity, err := deriveAndEncrypt(pub, secret, name, credential2B)
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if err != nil {
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return nil, nil, err
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}
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// Compute the HMAC of (encIdentity || name)
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identityHMAC, err := deriveAndHMAC(pub, secret, nil, encIdentity, name)
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if err != nil {
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return nil, nil, err
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}
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// Marshal the virtual TPMS_ID_OBJECT ourselves. We have to do this since encIdentity's size is encrypted.
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idObject = make([]byte, 0, 2+len(identityHMAC)+len(encIdentity))
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idObject = append(idObject, Marshal(TPM2BDigest{Buffer: identityHMAC})...)
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idObject = append(idObject, encIdentity...)
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return idObject, ciphertext, nil
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}
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