Updated ECDSA Signature Representation in the CHIP Certificate.

[emargolis]

Problem

Currently SDK implements ECDSA signature in the CHIP Certificate as a TLV structure of R and S parameters:

ecdsa-signature => STRUCTURE [tag-order]
{
r [1] : OCTET STRING,
s [2] : OCTET STRING,
}

Recently, the spec was updated to represent ECDSA signature as Octet String:

ec-signature => OCTET STRING [ length (CHIP_CRYPTO_GROUP_SIZE_BYTES * 2) ]

Change overview

• Added function to convert ASN.1 DER encoded Integers
• Added functions to convert ASN.1 DER encoded ECDSA signature
• Updated CHIP certificate structure to use new signature encoding
• Updated unit tests

Testing

Unit tests

Ticket #7382

[woody-apple]

@andy31415 @saurabhst @Damian-Nordic @msandstedt ?

[todo]

Consider renaming these values to be closer to definisions in the spec:

connectedhomeip/src/crypto/CHIPCryptoPAL.h

Lines 39 to 48 in 34bdbf0

	// TODO: Consider renaming these values to be closer to definisions in the spec:
	// CHIP_CRYPTO_GROUP_SIZE_BYTES
	// CHIP_CRYPTO_PUBLIC_KEY_SIZE_BYTES
	const size_t kP256_FE_Length = 32;
	const size_t kP256_ECDSA_Signature_Length_Raw = (2 * kP256_FE_Length);
	const size_t kP256_Point_Length = (2 * kP256_FE_Length + 1);
	const size_t kSHA256_Hash_Length = 32;
	const size_t kMax_ECDH_Secret_Length = kP256_FE_Length;
	const size_t kMax_ECDSA_Signature_Length = 72;

---

This comment was generated by todo based on a TODO comment in 34bdbf0 in #7384. cc @emargolis.

[woody-apple]

/rebase

[woody-apple]

@andy31415 ?

[woody-apple]

@saurabhst ?

[todo]

Review and consider replacing some data pointer/len pairs with ByteSpan and FixedByteSpan types.

connectedhomeip/src/credentials/CHIPCert.h

Lines 309 to 312 in 8e21a98

	// TODO: Review and consider replacing some data pointer/len pairs with ByteSpan and FixedByteSpan types.
	ByteSpan mCertificate; /**< Original raw buffer data. */
	ChipDN mSubjectDN; /**< Certificate Subject DN. */
	ChipDN mIssuerDN; /**< Certificate Issuer DN. */

---

This comment was generated by todo based on a TODO comment in 8e21a98 in #7384. cc @emargolis.

[github-actions]

Size increase report for "nrfconnect-example-build" from 2423a26

File	Section	File	VM
chip-lock.elf	device_handles	4	4
chip-lock.elf	text	-20	-20

Full report output

BLOAT REPORT

Files found only in the build output:
    report.csv

Comparing ./master_artifact/chip-shell.elf and ./pull_artifact/chip-shell.elf:

sections,vmsize,filesize
.debug_str,0,37
.debug_abbrev,0,20
.debug_line,0,4
.debug_loc,0,-1
.debug_info,0,-308

Comparing ./master_artifact/chip-lock.elf and ./pull_artifact/chip-lock.elf:

sections,vmsize,filesize
.debug_loc,0,1403
.debug_str,0,433
.debug_ranges,0,216
.strtab,0,199
.debug_frame,0,124
.debug_abbrev,0,109
.symtab,0,96
.debug_line,0,43
.debug_aranges,0,32
device_handles,4,4
.shstrtab,0,1
text,-20,-20
.debug_info,0,-104

[github-actions]

Size increase report for "esp32-example-build" from 2423a26

File	Section	File	VM
chip-all-clusters-app.elf	.flash.text	-8	-8

Full report output

BLOAT REPORT

Files found only in the build output:
    report.csv

Comparing ./master_artifact/chip-all-clusters-app.elf and ./pull_artifact/chip-all-clusters-app.elf:

sections,vmsize,filesize
.debug_loc,0,465
.debug_str,0,433
.debug_line,0,311
.debug_ranges,0,232
.strtab,0,199
.debug_frame,0,96
.symtab,0,48
.debug_aranges,0,32
.shstrtab,0,1
.flash.text,-8,-8
.debug_info,0,-585
.debug_abbrev,0,-800

Comparing ./master_artifact/chip-pigweed-app.elf and ./pull_artifact/chip-pigweed-app.elf:

sections,vmsize,filesize

[github-actions]

Size increase report for "gn_qpg6100-example-build" from 2423a26

File	Section	File	VM
chip-qpg6100-lighting-example.out	.text	-16	-16

Full report output

BLOAT REPORT

Files found only in the build output:
    report.csv

Comparing ./master_artifact/chip-qpg6100-lighting-example.out and ./pull_artifact/chip-qpg6100-lighting-example.out:

sections,vmsize,filesize
.debug_loc,0,1407
.debug_str,0,433
.debug_ranges,0,208
.strtab,0,199
.symtab,0,144
.debug_frame,0,120
.debug_line,0,57
.debug_aranges,0,32
[Unmapped],0,16
.shstrtab,0,1
.text,-16,-16
.debug_info,0,-26
.debug_abbrev,0,-503

Comparing ./master_artifact/chip-qpg6100-lighting-example.out.map and ./pull_artifact/chip-qpg6100-lighting-example.out.map:

BLOAT EXECUTION FAILED WITH CODE 1:
bloaty: unknown file type for file './pull_artifact/chip-qpg6100-lighting-example.out.map'