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ek,ak abstraction: align with TCG EK Credential Profile
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Signed-off-by: Thore Sommer <[email protected]>
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@THS-on
THS-on committed Oct 21, 2024
1 parent 2baa4d3 commit 2176c29
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99 changes: 88 additions & 11 deletions tss-esapi/src/abstraction/ak.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,9 +2,7 @@
// SPDX-License-Identifier: Apache-2.0

use crate::{
abstraction::{
cipher::Cipher, AsymmetricAlgorithmSelection, IntoKeyCustomization, KeyCustomization,
},
abstraction::{AsymmetricAlgorithmSelection, IntoKeyCustomization, KeyCustomization},
attributes::{ObjectAttributesBuilder, SessionAttributesBuilder},
constants::{AlgorithmIdentifier, SessionType},
handles::{AuthHandle, KeyHandle, SessionHandle},
Expand All @@ -16,13 +14,46 @@ use crate::{
session_handles::PolicySession,
},
structures::{
Auth, CreateKeyResult, EccPoint, EccScheme, KeyDerivationFunctionScheme, Private, Public,
PublicBuilder, PublicEccParametersBuilder, PublicKeyRsa, PublicRsaParametersBuilder,
RsaExponent, RsaScheme, SymmetricDefinitionObject,
Auth, CreateKeyResult, DigestList, EccPoint, EccScheme, KeyDerivationFunctionScheme,
Private, Public, PublicBuilder, PublicEccParametersBuilder, PublicKeyRsa,
PublicRsaParametersBuilder, RsaExponent, RsaScheme, SymmetricDefinitionObject,
},
Context, Error, Result, WrapperErrorKind,
};
use std::convert::{TryFrom, TryInto};
use std::convert::TryFrom;

// Source: TCG EK Credential Profile for TPM Family 2.0; Level 0 Version 2.5 Revision 2
// Section B.6
const POLICY_A_SHA384: [u8; 48] = [
0x8b, 0xbf, 0x22, 0x66, 0x53, 0x7c, 0x17, 0x1c, 0xb5, 0x6e, 0x40, 0x3c, 0x4d, 0xc1, 0xd4, 0xb6,
0x4f, 0x43, 0x26, 0x11, 0xdc, 0x38, 0x6e, 0x6f, 0x53, 0x20, 0x50, 0xc3, 0x27, 0x8c, 0x93, 0x0e,
0x14, 0x3e, 0x8b, 0xb1, 0x13, 0x38, 0x24, 0xcc, 0xb4, 0x31, 0x05, 0x38, 0x71, 0xc6, 0xdb, 0x53,
];
const POLICY_A_SHA512: [u8; 64] = [
0x1e, 0x3b, 0x76, 0x50, 0x2c, 0x8a, 0x14, 0x25, 0xaa, 0x0b, 0x7b, 0x3f, 0xc6, 0x46, 0xa1, 0xb0,
0xfa, 0xe0, 0x63, 0xb0, 0x3b, 0x53, 0x68, 0xf9, 0xc4, 0xcd, 0xde, 0xca, 0xff, 0x08, 0x91, 0xdd,
0x68, 0x2b, 0xac, 0x1a, 0x85, 0xd4, 0xd8, 0x32, 0xb7, 0x81, 0xea, 0x45, 0x19, 0x15, 0xde, 0x5f,
0xc5, 0xbf, 0x0d, 0xc4, 0xa1, 0x91, 0x7c, 0xd4, 0x2f, 0xa0, 0x41, 0xe3, 0xf9, 0x98, 0xe0, 0xee,
];
const POLICY_A_SM3_256: [u8; 32] = [
0xc6, 0x7f, 0x7d, 0x35, 0xf6, 0x6f, 0x3b, 0xec, 0x13, 0xc8, 0x9f, 0xe8, 0x98, 0x92, 0x1c, 0x65,
0x1b, 0x0c, 0xb5, 0xa3, 0x8a, 0x92, 0x69, 0x0a, 0x62, 0xa4, 0x3c, 0x00, 0x12, 0xe4, 0xfb, 0x8b,
];
const POLICY_C_SHA384: [u8; 48] = [
0xd6, 0x03, 0x2c, 0xe6, 0x1f, 0x2f, 0xb3, 0xc2, 0x40, 0xeb, 0x3c, 0xf6, 0xa3, 0x32, 0x37, 0xef,
0x2b, 0x6a, 0x16, 0xf4, 0x29, 0x3c, 0x22, 0xb4, 0x55, 0xe2, 0x61, 0xcf, 0xfd, 0x21, 0x7a, 0xd5,
0xb4, 0x94, 0x7c, 0x2d, 0x73, 0xe6, 0x30, 0x05, 0xee, 0xd2, 0xdc, 0x2b, 0x35, 0x93, 0xd1, 0x65,
];
const POLICY_C_SHA512: [u8; 64] = [
0x58, 0x9e, 0xe1, 0xe1, 0x46, 0x54, 0x47, 0x16, 0xe8, 0xde, 0xaf, 0xe6, 0xdb, 0x24, 0x7b, 0x01,
0xb8, 0x1e, 0x9f, 0x9c, 0x7d, 0xd1, 0x6b, 0x81, 0x4a, 0xa1, 0x59, 0x13, 0x87, 0x49, 0x10, 0x5f,
0xba, 0x53, 0x88, 0xdd, 0x1d, 0xea, 0x70, 0x2f, 0x35, 0x24, 0x0c, 0x18, 0x49, 0x33, 0x12, 0x1e,
0x2c, 0x61, 0xb8, 0xf5, 0x0d, 0x3e, 0xf9, 0x13, 0x93, 0xa4, 0x9a, 0x38, 0xc3, 0xf7, 0x3f, 0xc8,
];
const POLICY_C_SM3_256: [u8; 32] = [
0x2d, 0x4e, 0x81, 0x57, 0x8c, 0x35, 0x31, 0xd9, 0xbd, 0x1c, 0xdd, 0x7d, 0x02, 0xba, 0x29, 0x8d,
0x56, 0x99, 0xa3, 0xe3, 0x9f, 0xc3, 0x55, 0x1b, 0xfe, 0xff, 0xcf, 0x13, 0x2b, 0x49, 0xe1, 0x1d,
];

fn create_ak_public<IKC: IntoKeyCustomization>(
key_alg: AsymmetricAlgorithmSelection,
Expand Down Expand Up @@ -99,6 +130,35 @@ fn create_ak_public<IKC: IntoKeyCustomization>(
key_builder.build()
}

// extracts the hashing and sysmmetric algorithm from parent and constructs the correct DigestList for OR policy
fn session_config(
context: &mut Context,
parent: KeyHandle,
) -> Result<(HashingAlgorithm, SymmetricDefinitionObject, DigestList)> {
let parent_hash_alg = context.read_public(parent)?.0.name_hashing_algorithm();
let parent_symmetric = context.read_public(parent)?.0.symmetric_algorithm()?;

let mut policy_digests = DigestList::new();

match parent_hash_alg {
HashingAlgorithm::Sha384 => {
policy_digests.add(POLICY_A_SHA384.into())?;
policy_digests.add(POLICY_C_SHA384.into())?
}
HashingAlgorithm::Sha512 => {
policy_digests.add(POLICY_A_SHA512.into())?;
policy_digests.add(POLICY_C_SHA512.into())?
}
HashingAlgorithm::Sm3_256 => {
policy_digests.add(POLICY_A_SM3_256.into())?;
policy_digests.add(POLICY_C_SM3_256.into())?
}
_ => (),
};

Ok((parent_hash_alg, parent_symmetric, policy_digests))
}

/// This loads an Attestation Key previously generated under the Endorsement hierarchy
pub fn load_ak(
context: &mut Context,
Expand All @@ -107,14 +167,16 @@ pub fn load_ak(
private: Private,
public: Public,
) -> Result<KeyHandle> {
let (parent_hash_alg, parent_symmetric, policy_digests) = session_config(context, parent)?;

let policy_auth_session = context
.start_auth_session(
None,
None,
None,
SessionType::Policy,
Cipher::aes_128_cfb().try_into()?,
HashingAlgorithm::Sha256,
parent_symmetric.into(),
parent_hash_alg,
)?
.ok_or_else(|| Error::local_error(WrapperErrorKind::WrongValueFromTpm))?;

Expand Down Expand Up @@ -147,6 +209,13 @@ pub fn load_ak(
)
})?;

if !policy_digests.is_empty() {
ctx.policy_or(
PolicySession::try_from(policy_auth_session)?,
policy_digests,
)?
}

ctx.execute_with_session(Some(policy_auth_session), |ctx| {
ctx.load(parent, private, public)
})
Expand All @@ -171,15 +240,16 @@ pub fn create_ak<IKC: IntoKeyCustomization>(
key_customization: IKC,
) -> Result<CreateKeyResult> {
let ak_pub = create_ak_public(key_alg, hash_alg, sign_alg, key_customization)?;
let (parent_hash_alg, parent_symmetric, policy_digests) = session_config(context, parent)?;

let policy_auth_session = context
.start_auth_session(
None,
None,
None,
SessionType::Policy,
Cipher::aes_128_cfb().try_into()?,
HashingAlgorithm::Sha256,
parent_symmetric.into(),
parent_hash_alg,
)?
.ok_or_else(|| Error::local_error(WrapperErrorKind::WrongValueFromTpm))?;

Expand Down Expand Up @@ -212,6 +282,13 @@ pub fn create_ak<IKC: IntoKeyCustomization>(
)
})?;

if !policy_digests.is_empty() {
ctx.policy_or(
PolicySession::try_from(policy_auth_session)?,
policy_digests,
)?
};

ctx.execute_with_session(Some(policy_auth_session), |ctx| {
ctx.create(parent, ak_pub, ak_auth_value, None, None, None)
})
Expand Down
172 changes: 121 additions & 51 deletions tss-esapi/src/abstraction/ek.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -12,9 +12,9 @@ use crate::{
reserved_handles::{Hierarchy, NvAuth},
},
structures::{
Digest, EccParameter, EccPoint, EccScheme, KeyDerivationFunctionScheme, Public,
PublicBuilder, PublicEccParametersBuilder, PublicKeyRsa, PublicRsaParametersBuilder,
RsaExponent, RsaScheme, SymmetricDefinitionObject,
EccParameter, EccPoint, EccScheme, KeyDerivationFunctionScheme, Public, PublicBuilder,
PublicEccParametersBuilder, PublicKeyRsa, PublicRsaParametersBuilder, RsaExponent,
RsaScheme, SymmetricDefinitionObject,
},
Context, Error, Result, WrapperErrorKind,
};
Expand All @@ -32,8 +32,32 @@ const ECC_P256_SM2_EK_CERTIFICATE_NV_INDEX: u32 = 0x01c0001a;
const RSA_3072_EK_CERTIFICATE_NV_INDEX: u32 = 0x01c0001c;
const RSA_4096_EK_CERTIFICATE_NV_INDEX: u32 = 0x01c0001e;

// Source: TCG EK Credential Profile for TPM Family 2.0; Level 0 Version 2.5 Revision 2
// Section B.3 and B.4
const AUTHPOLICY_A_SHA256: [u8; 32] = [
0x83, 0x71, 0x97, 0x67, 0x44, 0x84, 0xb3, 0xf8, 0x1a, 0x90, 0xcc, 0x8d, 0x46, 0xa5, 0xd7, 0x24,
0xfd, 0x52, 0xd7, 0x6e, 0x06, 0x52, 0x0b, 0x64, 0xf2, 0xa1, 0xda, 0x1b, 0x33, 0x14, 0x69, 0xaa,
];
const AUTHPOLICY_B_SHA384: [u8; 48] = [
0xb2, 0x6e, 0x7d, 0x28, 0xd1, 0x1a, 0x50, 0xbc, 0x53, 0xd8, 0x82, 0xbc, 0xf5, 0xfd, 0x3a, 0x1a,
0x07, 0x41, 0x48, 0xbb, 0x35, 0xd3, 0xb4, 0xe4, 0xcb, 0x1c, 0x0a, 0xd9, 0xbd, 0xe4, 0x19, 0xca,
0xcb, 0x47, 0xba, 0x09, 0x69, 0x96, 0x46, 0x15, 0x0f, 0x9f, 0xc0, 0x00, 0xf3, 0xf8, 0x0e, 0x12,
];
const AUTHPOLICY_B_SHA512: [u8; 64] = [
0xb8, 0x22, 0x1c, 0xa6, 0x9e, 0x85, 0x50, 0xa4, 0x91, 0x4d, 0xe3, 0xfa, 0xa6, 0xa1, 0x8c, 0x07,
0x2c, 0xc0, 0x12, 0x08, 0x07, 0x3a, 0x92, 0x8d, 0x5d, 0x66, 0xd5, 0x9e, 0xf7, 0x9e, 0x49, 0xa4,
0x29, 0xc4, 0x1a, 0x6b, 0x26, 0x95, 0x71, 0xd5, 0x7e, 0xdb, 0x25, 0xfb, 0xdb, 0x18, 0x38, 0x42,
0x56, 0x08, 0xb4, 0x13, 0xcd, 0x61, 0x6a, 0x5f, 0x6d, 0xb5, 0xb6, 0x07, 0x1a, 0xf9, 0x9b, 0xea,
];
const AUTHPOLICY_B_SM3_256: [u8; 32] = [
0x16, 0x78, 0x60, 0xa3, 0x5f, 0x2c, 0x5c, 0x35, 0x67, 0xf9, 0xc9, 0x27, 0xac, 0x56, 0xc0, 0x32,
0xf3, 0xb3, 0xa6, 0x46, 0x2f, 0x8d, 0x03, 0x79, 0x98, 0xe7, 0xa1, 0x0f, 0x77, 0xfa, 0x45, 0x4a,
];

/// Get the [`Public`] representing a default Endorsement Key
///
/// **Note**: This only works for key algorithms specified in TCG EK Credential Profile for TPM Family 2.0.
///
/// Source: TCG EK Credential Profile for TPM Family 2.0; Level 0 Version 2.3 Revision 2
/// Appendix B.3.3 and B.3.4
pub fn create_ek_public_from_default_template<IKC: IntoKeyCustomization>(
Expand All @@ -42,12 +66,19 @@ pub fn create_ek_public_from_default_template<IKC: IntoKeyCustomization>(
) -> Result<Public> {
let key_customization = key_customization.into_key_customization();

// user_with_auth is not set for the lower profiles (RSA 20248 and ECC P256)
let user_with_auth = !matches!(
alg,
AsymmetricAlgorithmSelection::Rsa(RsaKeyBits::Rsa2048)
| AsymmetricAlgorithmSelection::Ecc(EccCurve::NistP256)
);

let obj_attrs_builder = ObjectAttributesBuilder::new()
.with_fixed_tpm(true)
.with_st_clear(false)
.with_fixed_parent(true)
.with_sensitive_data_origin(true)
.with_user_with_auth(false)
.with_user_with_auth(user_with_auth)
.with_admin_with_policy(true)
.with_no_da(false)
.with_encrypted_duplication(false)
Expand All @@ -62,54 +93,93 @@ pub fn create_ek_public_from_default_template<IKC: IntoKeyCustomization>(
}
.build()?;

// TPM2_PolicySecret(TPM_RH_ENDORSEMENT)
// With 32 null-bytes attached, because of the type of with_auth_policy
let authpolicy: [u8; 64] = [
0x83, 0x71, 0x97, 0x67, 0x44, 0x84, 0xb3, 0xf8, 0x1a, 0x90, 0xcc, 0x8d, 0x46, 0xa5, 0xd7,
0x24, 0xfd, 0x52, 0xd7, 0x6e, 0x06, 0x52, 0x0b, 0x64, 0xf2, 0xa1, 0xda, 0x1b, 0x33, 0x14,
0x69, 0xaa, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00,
];

let key_builder = match alg {
AsymmetricAlgorithmSelection::Rsa(key_bits) => PublicBuilder::new()
.with_public_algorithm(PublicAlgorithm::Rsa)
.with_name_hashing_algorithm(HashingAlgorithm::Sha256)
.with_object_attributes(obj_attrs)
.with_auth_policy(Digest::try_from(authpolicy[0..32].to_vec())?)
.with_rsa_parameters(
PublicRsaParametersBuilder::new()
.with_symmetric(SymmetricDefinitionObject::AES_128_CFB)
.with_scheme(RsaScheme::Null)
.with_key_bits(key_bits)
.with_exponent(RsaExponent::default())
.with_is_signing_key(obj_attrs.sign_encrypt())
.with_is_decryption_key(obj_attrs.decrypt())
.with_restricted(obj_attrs.decrypt())
.build()?,
)
.with_rsa_unique_identifier(PublicKeyRsa::new_empty_with_size(RsaKeyBits::Rsa2048)),
AsymmetricAlgorithmSelection::Ecc(ecc_curve) => PublicBuilder::new()
.with_public_algorithm(PublicAlgorithm::Ecc)
.with_name_hashing_algorithm(HashingAlgorithm::Sha256)
.with_object_attributes(obj_attrs)
.with_auth_policy(Digest::try_from(authpolicy[0..32].to_vec())?)
.with_ecc_parameters(
PublicEccParametersBuilder::new()
.with_symmetric(SymmetricDefinitionObject::AES_128_CFB)
.with_ecc_scheme(EccScheme::Null)
.with_curve(ecc_curve)
.with_key_derivation_function_scheme(KeyDerivationFunctionScheme::Null)
.with_is_signing_key(obj_attrs.sign_encrypt())
.with_is_decryption_key(obj_attrs.decrypt())
.with_restricted(obj_attrs.decrypt())
.build()?,
)
.with_ecc_unique_identifier(EccPoint::new(
EccParameter::try_from(vec![0u8; 32])?,
EccParameter::try_from(vec![0u8; 32])?,
)),
AsymmetricAlgorithmSelection::Rsa(key_bits) => {
let (hash_alg, authpolicy, symmetric, unique) = match key_bits {
RsaKeyBits::Rsa2048 => (
HashingAlgorithm::Sha256,
AUTHPOLICY_A_SHA256.into(),
SymmetricDefinitionObject::AES_128_CFB,
PublicKeyRsa::new_empty_with_size(RsaKeyBits::Rsa2048),
),
RsaKeyBits::Rsa3072 | RsaKeyBits::Rsa4096 => (
HashingAlgorithm::Sha384,
AUTHPOLICY_B_SHA384.into(),
SymmetricDefinitionObject::AES_256_CFB,
PublicKeyRsa::new_empty(),
),
// Other key sizes are not supported in the spec, so return a error
_ => return Err(Error::local_error(WrapperErrorKind::UnsupportedParam)),
};

PublicBuilder::new()
.with_public_algorithm(PublicAlgorithm::Rsa)
.with_name_hashing_algorithm(hash_alg)
.with_object_attributes(obj_attrs)
.with_auth_policy(authpolicy)
.with_rsa_parameters(
PublicRsaParametersBuilder::new()
.with_symmetric(symmetric)
.with_scheme(RsaScheme::Null)
.with_key_bits(key_bits)
.with_exponent(RsaExponent::default())
.with_is_signing_key(obj_attrs.sign_encrypt())
.with_is_decryption_key(obj_attrs.decrypt())
.with_restricted(obj_attrs.decrypt())
.build()?,
)
.with_rsa_unique_identifier(unique)
}
AsymmetricAlgorithmSelection::Ecc(ecc_curve) => {
let (hash_alg, authpolicy, symmetric, xy_size) = match ecc_curve {
EccCurve::NistP256 => (
HashingAlgorithm::Sha256,
AUTHPOLICY_A_SHA256.into(),
SymmetricDefinitionObject::AES_128_CFB,
32,
),
EccCurve::NistP384 => (
HashingAlgorithm::Sha384,
AUTHPOLICY_B_SHA384.into(),
SymmetricDefinitionObject::AES_256_CFB,
0,
),
EccCurve::NistP521 => (
HashingAlgorithm::Sha512,
AUTHPOLICY_B_SHA512.into(),
SymmetricDefinitionObject::AES_256_CFB,
0,
),
EccCurve::Sm2P256 => (
HashingAlgorithm::Sm3_256,
AUTHPOLICY_B_SM3_256.into(),
SymmetricDefinitionObject::SM4_128_CFB,
0,
),
// Other curves are not supported in the spec, so return a error
_ => return Err(Error::local_error(WrapperErrorKind::UnsupportedParam)),
};
PublicBuilder::new()
.with_public_algorithm(PublicAlgorithm::Ecc)
.with_name_hashing_algorithm(hash_alg)
.with_object_attributes(obj_attrs)
.with_auth_policy(authpolicy)
.with_ecc_parameters(
PublicEccParametersBuilder::new()
.with_symmetric(symmetric)
.with_ecc_scheme(EccScheme::Null)
.with_curve(ecc_curve)
.with_key_derivation_function_scheme(KeyDerivationFunctionScheme::Null)
.with_is_signing_key(obj_attrs.sign_encrypt())
.with_is_decryption_key(obj_attrs.decrypt())
.with_restricted(obj_attrs.decrypt())
.build()?,
)
.with_ecc_unique_identifier(EccPoint::new(
EccParameter::try_from(vec![0u8; xy_size])?,
EccParameter::try_from(vec![0u8; xy_size])?,
))
}
};

let key_builder = if let Some(ref k) = key_customization {
Expand Down
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