Skip to content

Commit da19580

Browse files
zhalvorsenzhalvorsen
committed
dpe: Resolve feedback items from #66
Fixes #86 * Adds maximum certificate size for ML-DSA * Adds a remaining field to GetCertificateChain to fix the corner case where GetCertificateChainResponse.size == the size of the certificate * Adds detail about ML-DSA private key derivation Signed-off-by: Zach Halvorsen <zhalvorsen@google.com>
1 parent 918b100 commit da19580

1 file changed

Lines changed: 41 additions & 36 deletions

File tree

‎specifications/dpe-irot-profile/spec.ocp‎

Lines changed: 41 additions & 36 deletions
Original file line numberDiff line numberDiff line change
@@ -204,6 +204,19 @@ in the command-specific "ABI" sections in @sec:abi-structure-definitions.
204204

205205
Full structure definitions are provided at the end of this document.
206206

207+
## Multi-part Operations
208+
209+
This profile supports multi-part operations for commands that return large
210+
amounts of data. This functionality is currently limited to the response data of
211+
`CertifyKey`, `GetCertificateChain`, and `DeriveContext` when exporting a CDI.
212+
Unlike the DPE specification [@{tcg-dpe}], which uses a `more-data` flag, this
213+
profile uses the `OP_HANDLE` field to indicate availability of additional data.
214+
When an operation has more data to return, the `OP_HANDLE` in the response will
215+
be non-zero. To retrieve the remaining data, the caller SHALL issue a subsequent
216+
request with the `OP_HANDLE` set to the value received in the preceding
217+
response, while keeping all other input parameters identical to the initial
218+
request. The operation is complete when the returned `OP_HANDLE` is all zeros.
219+
207220
## Supported Commands
208221

209222
This section describes commands supported by this profile.
@@ -499,18 +512,6 @@ The CDI derivation scheme “ocp.derive.kdf-cdi-384” is defined as follows:
499512
* Outputs
500513
* 48-byte key
501514

502-
### ocp.derive.kdf-cdi-512
503-
504-
The CDI derivation scheme “ocp.derive.kdf-cdi-512” is defined as follows:
505-
506-
* This derivation scheme SHALL use a cryptographically secure KDF or DRBG.
507-
* Inputs
508-
* CDI
509-
* `MEASUREMENT_DATA`
510-
* ASCII Bytes "DPE"
511-
* Outputs
512-
* 64-byte key
513-
514515
## CDI Export
515516

516517
### ocp.export-cdi.raw-256
@@ -525,12 +526,6 @@ The CDI export scheme "ocp.export-cdi.raw" is a raw 384-bit secret
525526

526527
To generate exported keypair, use asymmetric-derivation for the relevant profile.
527528

528-
### ocp.export-cdi.raw-512
529-
530-
The CDI export scheme "ocp.export-cdi.raw" is a raw 512-bit secret
531-
532-
To generate exported keypair, use asymmetric-derivation for the relevant profile.
533-
534529
## Key Derivation
535530

536531
* `LABEL`: LABEL parameter passed to Sign and CertifyKey
@@ -573,13 +568,19 @@ follows:
573568

574569
* The asymmetric key type is ML-DSA-87
575570
* Signature scheme is ML-DSA
576-
* This derivation scheme SHALL use a cryptographically secure KDF or DRBG.
571+
* This derivation scheme SHALL use the following sequence.
572+
* Use a cryptographically secure KDF or DRBG to derive 32-byte seed 𝜉 (xi).
577573
* Inputs
578574
* CDI
579575
* `LABEL`
580576
* ASCII Bytes "MLDSA"
581577
* Outputs
582-
* 64-byte key
578+
* 32-byte xi
579+
* Use ML-DSA.KeyGen_internal (Algorithm 6) to derive the private key [@{fips204}].
580+
* Inputs
581+
* 32-byte xi
582+
* Outputs
583+
* 4,896-byte key
583584

584585
### ocp.key-format.p384.raw
585586

@@ -852,7 +853,7 @@ The format “ocp.certificate.irot-eca.mldsa87” is defined as follows:
852853

853854
* SHALL follow all "Requirements for ECA Certificates" in @sec:eca-cert-requirements
854855
* For FWID hashAlg fields provided by DeriveContext, DPE SHALL use the
855-
SHA2-512 OID.
856+
SHA2-384 OID.
856857
* For the SubjectPublicKeyInfo field, DPE SHALL use the ML-DSA-87 OID.
857858
* For the Signature field, DPE SHALL use the ML-DSA-87 OID.
858859

@@ -886,7 +887,7 @@ The format “ocp.certificate.irot-eca.mldsa87” is defined as follows:
886887

887888
* SHALL follow all "Requirements for ECA Certificates" in @sec:eca-cert-requirements
888889
* For FWID hashAlg fields provided by DeriveContext, DPE SHALL use the
889-
SHA2-512 OID.
890+
SHA2-384 OID.
890891
* For the SubjectPublicKeyInfo field, DPE SHALL use the ML-DSA-87 OID.
891892
* For the Signature field, DPE SHALL use the ML-DSA-87 OID.
892893

@@ -920,7 +921,7 @@ The format “ocp.csr.irot-eca.mldsa87” is defined as follows:
920921

921922
* SHALL follow all "Requirements for CSRs" in @sec:csr-requirements
922923
* For FWID hashAlg fields provided by DeriveContext, DPE SHALL use the
923-
SHA2-512 OID.
924+
SHA2-384 OID.
924925
* For the SubjectPublicKeyInfo field, DPE SHALL use the ML-DSA-87 OID.
925926
* For the Signature of both the CMS message and the CertificationRequest, DPE SHALL
926927
use the ML-DSA-87 OID.
@@ -942,7 +943,7 @@ The format “ocp.csr.irot-eca.mldsa87” is defined as follows:
942943
+-------------------------------+------------------------------------------------------------------+
943944
| max-message-size | 6144 |
944945
+-------------------------------+------------------------------------------------------------------+
945-
| uses-multi-part-messages | False |
946+
| uses-multi-part-messages | True. See @sec:multi-part-operations for more information. |
946947
+-------------------------------+------------------------------------------------------------------+
947948
| supports-concurrent-operation | False |
948949
+-------------------------------+------------------------------------------------------------------+
@@ -1286,7 +1287,7 @@ The format “ocp.csr.irot-eca.mldsa87” is defined as follows:
12861287
+-------------------------------+------------------------------------------------------------------+
12871288
| ========================================= Derivation =========================================== |
12881289
+-------------------------------+------------------------------------------------------------------+
1289-
| dice-derivation | ocp.derive.kdf-cdi-512 |
1290+
| dice-derivation | ocp.derive.kdf-cdi-384 |
12901291
+-------------------------------+------------------------------------------------------------------+
12911292
| asymmetric-derivation | ocp.derive.kdf-asymmetric-mldsa87 |
12921293
+-------------------------------+------------------------------------------------------------------+
@@ -1306,7 +1307,7 @@ The format “ocp.csr.irot-eca.mldsa87” is defined as follows:
13061307
+-------------------------------+------------------------------------------------------------------+
13071308
| =========================================== Export ============================================= |
13081309
+-------------------------------+------------------------------------------------------------------+
1309-
| export-cdi-format | ocp.export-cdi.raw-512 |
1310+
| export-cdi-format | ocp.export-cdi.raw-384 |
13101311
+-------------------------------+------------------------------------------------------------------+
13111312

13121313
## ABI Structure Definitions {#sec:abi-structure-definitions}
@@ -1433,10 +1434,10 @@ Table: Profile-dependant ABI constants for `DPE_PROFILE_IROT_MLDSA87_SHA384`
14331434

14341435
**Name** | **Description** | **Value**
14351436
------------ | --------------------- | --------
1436-
`H` | Hash Size | 64
1437+
`H` | Hash Size | 48
14371438
`P` | Public Key Size | 2592
14381439
`S` | Signature Size | 4697
1439-
`C` | Certificate Size | TODO
1440+
`C` | Certificate Size | 17408
14401441

14411442
### Types
14421443

@@ -1548,6 +1549,7 @@ Table: `DERIVE_CONTEXT_INPUT_ARGS` struct
15481549
| 0x20 + H | `BYTES` | 31:0 | `INPUT_TYPE` | 4-byte measurement type field
15491550
| 0x24 + H | `U32` | 31:0 | `TARGET_LOCALITY` | Locality in which `NEW_CONTEXT_HANDLE` will be created if `CHANGE_LOCALITY` is set.
15501551
| 0x28 + H | `U32` | 31:0 | `INPUT_SVN` | SVN added to TCI node. Callers SHOULD set this field to `0` when SVN is unused.
1552+
| 0x2C + H | `BYTES` | 127:0 | `OP_HANDLE` | A handle if continuing a multi-part operation, otherwise 0.
15511553

15521554
Table: `DERIVE_CONTEXT_OUTPUT_ARGS` struct if `EXPORT_CDI` is **not** set
15531555

@@ -1569,8 +1571,9 @@ Table: `DERIVE_CONTEXT_OUTPUT_ARGS` struct if `EXPORT_CDI` is set
15691571
| 0x0C | `BYTES` | 127:0 | `NEW_CONTEXT_HANDLE` | The handle for the created child context, or rotated context in case RECURSIVE is set.
15701572
| 0x1C | `BYTES` | 127:0 | `PARENT_CONTEXT_HANDLE` | The handle for the parent context if `RETAIN_PARENT_CONTEXT` is set.
15711573
| 0x2C | `EXPORTED_CDI` | 255:0 | `EXPORTED_CDI` | If EXPORT_CDI is true, holds exported CDI. Else, value is ignored.
1572-
| 0x4C | `U32` | 31:0 | `CERTIFICATE_SIZE` | Number of bytes used in `NEW_CERTIFICATE`.
1573-
| 0x50 | `BYTES` | | `NEW_CERTIFICATE` | If CREATE_CERTIFICATE is set, holds the new ECA certificate. Else, value is ignored.
1574+
| 0x4C | `BYTES` | 127:0 | `OP_HANDLE` | Contains a handle if more data remains in the certificate, otherwise 0.
1575+
| 0x5C | `U32` | 31:0 | `CERTIFICATE_SIZE` | Number of bytes used in `NEW_CERTIFICATE`.
1576+
| 0x60 | `BYTES` | | `NEW_CERTIFICATE` | If CREATE_CERTIFICATE is set, holds the new ECA certificate. Else, value is ignored.
15741577

15751578
#### CertifyKey ABI
15761579

@@ -1585,6 +1588,7 @@ Table: `CERTIFY_KEY_INPUT_ARGS` struct
15851588
| 0x1C | `BITFIELD` | 31:0 | `RESERVED` | Reserved
15861589
| 0x20 | `U32` | 31:0 | `ADD_FORMAT` | Output format of `CERTIFICATE`
15871590
| 0x24 | `HASH` | | `LABEL` | Public digest used in key derivation.
1591+
| 0x24 + H | `BYTES` | 127:0 | `OP_HANDLE` | A handle if continuing a multi-part operation, otherwise 0.
15881592

15891593
Table: `CERTIFY_KEY_OUTPUT_ARGS` struct
15901594

@@ -1595,8 +1599,9 @@ Table: `CERTIFY_KEY_OUTPUT_ARGS` struct
15951599
| 0x08 | `U32` | 31:0 | `PROFILE` | One of `DPE_PROFILE_*`.
15961600
| 0x0C | `BYTES` | 127:0 | `NEW_CONTEXT_HANDLE` | Numeric handle referring to the updated context.
15971601
| 0x1C | `PUBKEY` | | `DERIVED_PUBLIC_KEY` | Derived public key. This is the same public key as the Subject of the returned certificate.
1598-
| 0x1C + P | `U32` | 31:0 | `CERTIFICATE_SIZE` | Number of bytes used in `CERTIFICATE_CHAIN`.
1599-
| 0x20 + P | `CERTIFICATE` | | `CERTIFICATE` | Returned leaf certificate.
1602+
| 0x1C + P | `BYTES` | 127:0 | `OP_HANDLE` | Contains a handle if more data remains in the certificate, otherwise 0.
1603+
| 0x2C + P | `U32` | 31:0 | `CERTIFICATE_SIZE` | Number of bytes used in `CERTIFICATE_CHAIN`.
1604+
| 0x30 + P | `CERTIFICATE` | | `CERTIFICATE` | Returned leaf certificate.
16001605

16011606
#### Sign ABI
16021607

@@ -1673,8 +1678,7 @@ Table: `GET_CERTIFICATE_CHAIN_INPUT_ARGS` struct
16731678
| 0x00 | `U32` | 31:0 | `MAGIC` | Magic number `DPE_COMMAND_MAGIC`.
16741679
| 0x04 | `U32` | 31:0 | `COMMAND_ID` | `DPE_COMMAND_GET_CERTIFICATE_CHAIN`.
16751680
| 0x08 | `U32` | 31:0 | `PROFILE` | One of `DPE_PROFILE_*`.
1676-
| 0x0C | `U32` | 31:0 | `OFFSET` | Offset of certificate chain to retrieve.
1677-
| 0x10 | `U32` | 31:0 | `SIZE` | Max number of bytes to return, starting at `OFFSET`.
1681+
| 0x0C | `BYTES` | 127:0 | `OP_HANDLE` | A handle if continuing a multi-part operation, otherwise 0.
16781682

16791683
Table: `GET_CERTIFICATE_CHAIN_OUTPUT_ARGS` struct
16801684

@@ -1683,5 +1687,6 @@ Table: `GET_CERTIFICATE_CHAIN_OUTPUT_ARGS` struct
16831687
| 0x00 | `U32` | 31:0 | `MAGIC` | Magic number `DPE_RESPONSE_MAGIC`.
16841688
| 0x04 | `U32` | 31:0 | `STATUS` | One of `DPE_STATUS_*`.
16851689
| 0x08 | `U32` | 31:0 | `PROFILE` | One of `DPE_PROFILE_*`.
1686-
| 0x0C | `U32` | 31:0 | `CERTIFICATE_SIZE` | Number of bytes used in `CERTIFICATE_CHAIN`. Can be smaller than requested if no bytes are left to read.
1687-
| 0x10 | `BYTES` | 16383:0 | `CERTIFICATE_CHAIN` | Returned certificate chain. This may be a partial certificate chain.
1690+
| 0x0C | `BYTES` | 127:0 | `OP_HANDLE` | Contains a handle if more data remains in the certificate chain, otherwise 0.
1691+
| 0x10 | `U32` | 31:0 | `CERTIFICATE_SIZE` | Number of bytes used in `CERTIFICATE_CHAIN`. Can be smaller than requested if no bytes are left to read.
1692+
| 0x14 | `BYTES` | | `CERTIFICATE_CHAIN` | Returned certificate chain. This may be a partial certificate chain.

0 commit comments

Comments
 (0)