COCOS-560 - EAT (#561)

* feat: Implement EAT (Evidence Attestation Token) generation and verification for attestation responses, replacing raw quotes with EAT tokens in the attestation service and protobuf.

Signed-off-by: Sammy Oina <sammyoina@gmail.com>

* style: standardize comment formatting and fix a debug log format specifier.

Signed-off-by: Sammy Oina <sammyoina@gmail.com>

* fix pkg test

Signed-off-by: Sammy Oina <sammyoina@gmail.com>

* feat: Introduce named constants for OEM IDs and use them in attestation claim extraction.

Signed-off-by: SammyOina <sammyoina@gmail.com>

* feat: Implement and test minimum length validation for EAT nonce in `NewEATClaims`.

Signed-off-by: SammyOina <sammyoina@gmail.com>

* feat: Add EATClaims.Sanitize method and integrate it into the validator to enforce claim dependencies.

Signed-off-by: SammyOina <sammyoina@gmail.com>

* feat: Add Signature field to SNPExtensions and TDXExtensions for enhanced claim validation

Signed-off-by: Sammy Oina <sammyoina@gmail.com>

* feat: Update dependencies and improve code structure in attestation package

Signed-off-by: Sammy Oina <sammyoina@gmail.com>

* feat: Introduce comprehensive test suites for EAT, ATLS, TDX, Azure SNP, and vTPM attestation, and improve EAT decoder robustness.

Signed-off-by: Sammy Oina <sammyoina@gmail.com>

* feat: Add encryption and admin keys, an encrypted algorithm file, and update go.mod to use go-jose/v4.

Signed-off-by: Sammy Oina <sammyoina@gmail.com>

* feat: add new encryption and KBS admin keys while improving TDX attestation test error handling.

Signed-off-by: Sammy Oina <sammyoina@gmail.com>

* feat: Add new KBS admin and encryption keys, an encrypted linear regression algorithm, and refactor TDX test error message checks.

Signed-off-by: Sammy Oina <sammyoina@gmail.com>

* feat: Implement Azure SNP attestation policy, update certificate verification, and add key management.

Signed-off-by: Sammy Oina <sammyoina@gmail.com>

* refactor: replace hardcoded string literals with variables in Azure SNP attestation tests.

Signed-off-by: Sammy Oina <sammyoina@gmail.com>

* feat: Refactor TDX EAT claims to use individual RTMR fields with `tdx_` prefixes and add an `IntUse` field.

Signed-off-by: Sammy Oina <sammyoina@gmail.com>

---------

Signed-off-by: Sammy Oina <sammyoina@gmail.com>
Signed-off-by: SammyOina <sammyoina@gmail.com>

pkg/clients/grpc/attestation/client.go

@@ -68,7 +68,7 @@ func (c *client) GetAttestation(ctx context.Context, reportData [64]byte, nonce
 		return nil, err
 	}
 
-	return resp.Quote, nil
+	return resp.EatToken, nil
 }
 
 func (c *client) GetAzureToken(ctx context.Context, nonce [32]byte) ([]byte, error) {