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Adding AttestationReport Verification with Certificate only #266

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Adding AttestationReport Verification with Certificate only #266

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84 changes: 78 additions & 6 deletions src/firmware/guest/types/snp.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@
use crate::{certs::snp::ecdsa::Signature, firmware::host::TcbVersion, util::hexdump};

#[cfg(any(feature = "openssl", feature = "crypto_nossl"))]
use crate::certs::snp::{Chain, Verifiable};
use crate::certs::snp::{Certificate, Chain, Verifiable};

use std::fmt::Display;

Expand Down Expand Up @@ -314,7 +314,7 @@ impl Verifiable for (&Chain, &AttestationReport) {
type Output = ();

fn verify(self) -> io::Result<Self::Output> {
let vcek = self.0.verify()?;
let vek = self.0.verify()?;

let sig = EcdsaSig::try_from(&self.1.signature)?;
let measurable_bytes: &[u8] = &bincode::serialize(self.1).map_err(|e| {
Expand All @@ -328,14 +328,46 @@ impl Verifiable for (&Chain, &AttestationReport) {
hasher.update(measurable_bytes);
let base_digest = hasher.finish();

let ec = vcek.public_key()?.ec_key()?;
let ec = vek.public_key()?.ec_key()?;
let signed = sig.verify(&base_digest, &ec)?;

match signed {
true => Ok(()),
false => Err(Error::new(
ErrorKind::Other,
"VCEK does not sign the attestation report",
"VEK does not sign the attestation report",
)),
}
}
}

#[cfg(feature = "openssl")]
impl Verifiable for (&Certificate, &AttestationReport) {
type Output = ();

fn verify(self) -> io::Result<Self::Output> {
let vek = self.0;

let sig = EcdsaSig::try_from(&self.1.signature)?;
let measurable_bytes: &[u8] = &bincode::serialize(self.1).map_err(|e| {
Error::new(
ErrorKind::Other,
format!("Unable to serialize bytes: {}", e),
)
})?[..0x2a0];

let mut hasher = Sha384::new();
hasher.update(measurable_bytes);
let base_digest = hasher.finish();

let ec = vek.public_key()?.ec_key()?;
let signed = sig.verify(&base_digest, &ec)?;

match signed {
true => Ok(()),
false => Err(Error::new(
ErrorKind::Other,
"VEK does not sign the attestation report",
)),
}
}
Expand All @@ -345,13 +377,53 @@ impl Verifiable for (&Chain, &AttestationReport) {
impl Verifiable for (&Chain, &AttestationReport) {
type Output = ();

fn verify(self) -> io::Result<Self::Output> {
// According to Chapter 3 of the Versioned Chip Endorsement Key (VCEK) Certificate and the Versioned Loaded Endorsement Key (VLEK)
// Certificate specifications, both Versioned Endorsement Key certificates certify an ECDSA public key on curve P-384,
// with the signature hash algorithm being SHA-384.
let vek = self.0.verify()?;

let sig = p384::ecdsa::Signature::try_from(&self.1.signature)?;

let measurable_bytes: &[u8] = &bincode::serialize(self.1).map_err(|e| {
Error::new(
ErrorKind::Other,
format!("Unable to serialize bytes: {}", e),
)
})?[..0x2a0];

use sha2::Digest;
let base_digest = sha2::Sha384::new_with_prefix(measurable_bytes);

let verifying_key = p384::ecdsa::VerifyingKey::from_sec1_bytes(vek.public_key_sec1())
.map_err(|e| {
io::Error::new(
ErrorKind::Other,
format!("failed to deserialize public key from sec1 bytes: {e:?}"),
)
})?;

use p384::ecdsa::signature::DigestVerifier;
verifying_key.verify_digest(base_digest, &sig).map_err(|e| {
io::Error::new(
ErrorKind::Other,
format!("VCEK does not sign the attestation report: {e:?}"),
)
})
}
}

#[cfg(feature = "crypto_nossl")]
impl Verifiable for (&Certificate, &AttestationReport) {
type Output = ();

fn verify(self) -> io::Result<Self::Output> {
// According to Chapter 3 of the [Versioned Chip Endorsement Key (VCEK) Certificate and
// KDS Interface Specification][spec], the VCEK certificate certifies an ECDSA public key on curve P-384,
// and the signature hash algorithm is sha384.
// [spec]: https://www.amd.com/content/dam/amd/en/documents/epyc-technical-docs/specifications/57230.pdf

let vcek = self.0.verify()?;
let vek = self.0;

let sig = p384::ecdsa::Signature::try_from(&self.1.signature)?;

Expand All @@ -365,7 +437,7 @@ impl Verifiable for (&Chain, &AttestationReport) {
use sha2::Digest;
let base_digest = sha2::Sha384::new_with_prefix(measurable_bytes);

let verifying_key = p384::ecdsa::VerifyingKey::from_sec1_bytes(vcek.public_key_sec1())
let verifying_key = p384::ecdsa::VerifyingKey::from_sec1_bytes(vek.public_key_sec1())
.map_err(|e| {
io::Error::new(
ErrorKind::Other,
Expand Down
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