diff options
Diffstat (limited to 'packages/server/src')
3 files changed, 35 insertions, 65 deletions
diff --git a/packages/server/src/attestation/verifications/tpm/parseCertInfo.ts b/packages/server/src/attestation/verifications/tpm/parseCertInfo.ts index e7c9225..1ac391e 100644 --- a/packages/server/src/attestation/verifications/tpm/parseCertInfo.ts +++ b/packages/server/src/attestation/verifications/tpm/parseCertInfo.ts @@ -4,32 +4,25 @@ import { TPM_ST, TPM_ALG } from './constants'; * Cut up a TPM attestation's certInfo into intelligible chunks */ export default function parseCertInfo(certInfo: Buffer): ParsedCertInfo { - let certBuffer = certInfo; + let pointer = 0; // Get a magic constant - const magic = certBuffer.slice(0, 4).readUInt32BE(0); - certBuffer = certBuffer.slice(4); + const magic = certInfo.slice(pointer, (pointer += 4)).readUInt32BE(0); // Determine the algorithm used for attestation - const typeBuffer = certBuffer.slice(0, 2); - certBuffer = certBuffer.slice(2); + const typeBuffer = certInfo.slice(pointer, (pointer += 2)); const type = TPM_ST[typeBuffer.readUInt16BE(0)]; // The name of a parent entity, can be ignored - const qualifiedSignerLength = certBuffer.slice(0, 2).readUInt16BE(0); - certBuffer = certBuffer.slice(2); - const qualifiedSigner = certBuffer.slice(0, qualifiedSignerLength); - certBuffer = certBuffer.slice(qualifiedSignerLength); + const qualifiedSignerLength = certInfo.slice(pointer, (pointer += 2)).readUInt16BE(0); + const qualifiedSigner = certInfo.slice(pointer, (pointer += qualifiedSignerLength)); // Get the expected hash of `attsToBeSigned` - const extraDataLength = certBuffer.slice(0, 2).readUInt16BE(0); - certBuffer = certBuffer.slice(2); - const extraData = certBuffer.slice(0, extraDataLength); - certBuffer = certBuffer.slice(extraDataLength); + const extraDataLength = certInfo.slice(pointer, (pointer += 2)).readUInt16BE(0); + const extraData = certInfo.slice(pointer, (pointer += extraDataLength)); // Information about the TPM device's internal clock, can be ignored - const clockInfoBuffer = certBuffer.slice(0, 17); - certBuffer = certBuffer.slice(17); + const clockInfoBuffer = certInfo.slice(pointer, (pointer += 17)); const clockInfo = { clock: clockInfoBuffer.slice(0, 8), resetCount: clockInfoBuffer.slice(8, 12).readUInt32BE(0), @@ -38,20 +31,15 @@ export default function parseCertInfo(certInfo: Buffer): ParsedCertInfo { }; // TPM device firmware version - const firmwareVersion = certBuffer.slice(0, 8); - certBuffer = certBuffer.slice(8); + const firmwareVersion = certInfo.slice(pointer, (pointer += 8)); // Attested Name - const attestedNameLength = certBuffer.slice(0, 2).readUInt16BE(0); - certBuffer = certBuffer.slice(2); - const attestedName = certBuffer.slice(0, attestedNameLength); - certBuffer = certBuffer.slice(attestedNameLength); + const attestedNameLength = certInfo.slice(pointer, (pointer += 2)).readUInt16BE(0); + const attestedName = certInfo.slice(pointer, (pointer += attestedNameLength)); // Attested qualified name, can be ignored - const qualifiedNameLength = certBuffer.slice(0, 2).readUInt16BE(0); - certBuffer = certBuffer.slice(2); - const qualifiedName = certBuffer.slice(0, qualifiedNameLength); - certBuffer = certBuffer.slice(qualifiedNameLength); + const qualifiedNameLength = certInfo.slice(pointer, (pointer += 2)).readUInt16BE(0); + const qualifiedName = certInfo.slice(pointer, (pointer += qualifiedNameLength)); const attested = { nameAlg: TPM_ALG[attestedName.slice(0, 2).readUInt16BE(0)], diff --git a/packages/server/src/attestation/verifications/tpm/parsePubArea.ts b/packages/server/src/attestation/verifications/tpm/parsePubArea.ts index a9ee374..5f0d63b 100644 --- a/packages/server/src/attestation/verifications/tpm/parsePubArea.ts +++ b/packages/server/src/attestation/verifications/tpm/parsePubArea.ts @@ -4,19 +4,16 @@ import { TPM_ALG, TPM_ECC_CURVE } from './constants'; * Break apart a TPM attestation's pubArea buffer */ export default function parsePubArea(pubArea: Buffer): ParsedPubArea { - let pubBuffer: Buffer = pubArea; + let pointer = 0; - const typeBuffer = pubBuffer.slice(0, 2); - pubBuffer = pubBuffer.slice(2); + const typeBuffer = pubArea.slice(pointer, (pointer += 2)); const type = TPM_ALG[typeBuffer.readUInt16BE(0)]; - const nameAlgBuffer = pubBuffer.slice(0, 2); - pubBuffer = pubBuffer.slice(2); + const nameAlgBuffer = pubArea.slice(pointer, (pointer += 2)); const nameAlg = TPM_ALG[nameAlgBuffer.readUInt16BE(0)]; // Get some authenticator attributes(?) - const objectAttributesInt = pubBuffer.slice(0, 4).readUInt32BE(0); - pubBuffer = pubBuffer.slice(4); + const objectAttributesInt = pubArea.slice(pointer, (pointer += 4)).readUInt32BE(0); const objectAttributes = { fixedTPM: !!(objectAttributesInt & 1), stClear: !!(objectAttributesInt & 2), @@ -32,16 +29,13 @@ export default function parsePubArea(pubArea: Buffer): ParsedPubArea { }; // Slice out the authPolicy of dynamic length - const authPolicyLength = pubBuffer.slice(0, 2).readUInt16BE(0); - pubBuffer = pubBuffer.slice(2); - const authPolicy = pubBuffer.slice(0, authPolicyLength); - pubBuffer = pubBuffer.slice(authPolicyLength); + const authPolicyLength = pubArea.slice(pointer, (pointer += 2)).readUInt16BE(0); + const authPolicy = pubArea.slice(pointer, (pointer += authPolicyLength)); // Extract additional curve params according to type const parameters: { rsa?: RSAParameters; ecc?: ECCParameters } = {}; if (type === 'TPM_ALG_RSA') { - const rsaBuffer = pubBuffer.slice(0, 10); - pubBuffer = pubBuffer.slice(10); + const rsaBuffer = pubArea.slice(pointer, (pointer += 10)); parameters.rsa = { symmetric: TPM_ALG[rsaBuffer.slice(0, 2).readUInt16BE(0)], @@ -50,8 +44,7 @@ export default function parsePubArea(pubArea: Buffer): ParsedPubArea { exponent: rsaBuffer.slice(6, 10).readUInt32BE(0), }; } else if (type === 'TPM_ALG_ECC') { - const eccBuffer = pubBuffer.slice(0, 8); - pubBuffer = pubBuffer.slice(8); + const eccBuffer = pubArea.slice(pointer, (pointer += 8)); parameters.ecc = { symmetric: TPM_ALG[eccBuffer.slice(0, 2).readUInt16BE(0)], @@ -64,10 +57,8 @@ export default function parsePubArea(pubArea: Buffer): ParsedPubArea { } // Slice out unique of dynamic length - const uniqueLength = pubBuffer.slice(0, 2).readUInt16BE(0); - pubBuffer = pubBuffer.slice(2); - const unique = pubBuffer.slice(0, uniqueLength); - pubBuffer = pubBuffer.slice(uniqueLength); + const uniqueLength = pubArea.slice(pointer, (pointer += 2)).readUInt16BE(0); + const unique = pubArea.slice(pointer, (pointer += uniqueLength)); return { type, diff --git a/packages/server/src/helpers/parseAuthenticatorData.ts b/packages/server/src/helpers/parseAuthenticatorData.ts index cce6756..9b13195 100644 --- a/packages/server/src/helpers/parseAuthenticatorData.ts +++ b/packages/server/src/helpers/parseAuthenticatorData.ts @@ -11,14 +11,11 @@ export default function parseAuthenticatorData(authData: Buffer): ParsedAuthenti ); } - let intBuffer = authData; + let pointer = 0; - const rpIdHash = intBuffer.slice(0, 32); - intBuffer = intBuffer.slice(32); - - const flagsBuf = intBuffer.slice(0, 1); - intBuffer = intBuffer.slice(1); + const rpIdHash = authData.slice(pointer, (pointer += 32)); + const flagsBuf = authData.slice(pointer, (pointer += 1)); const flagsInt = flagsBuf[0]; const flags = { @@ -29,9 +26,7 @@ export default function parseAuthenticatorData(authData: Buffer): ParsedAuthenti flagsInt, }; - const counterBuf = intBuffer.slice(0, 4); - intBuffer = intBuffer.slice(4); - + const counterBuf = authData.slice(pointer, (pointer += 4)); const counter = counterBuf.readUInt32BE(0); let aaguid: Buffer | undefined = undefined; @@ -39,33 +34,29 @@ export default function parseAuthenticatorData(authData: Buffer): ParsedAuthenti let credentialPublicKey: Buffer | undefined = undefined; if (flags.at) { - aaguid = intBuffer.slice(0, 16); - intBuffer = intBuffer.slice(16); - - const credIDLenBuf = intBuffer.slice(0, 2); - intBuffer = intBuffer.slice(2); + aaguid = authData.slice(pointer, (pointer += 16)); + const credIDLenBuf = authData.slice(pointer, (pointer += 2)); const credIDLen = credIDLenBuf.readUInt16BE(0); - credentialID = intBuffer.slice(0, credIDLen); - intBuffer = intBuffer.slice(credIDLen); + credentialID = authData.slice(pointer, (pointer += credIDLen)); // Decode the next CBOR item in the buffer, then re-encode it back to a Buffer - const firstDecoded = decodeCborFirst(intBuffer); + const firstDecoded = decodeCborFirst(authData.slice(pointer)); const firstEncoded = Buffer.from(cbor.encode(firstDecoded) as ArrayBuffer); credentialPublicKey = firstEncoded; - intBuffer = intBuffer.slice(firstEncoded.byteLength); + authData = authData.slice((pointer += firstEncoded.byteLength)); } let extensionsDataBuffer: Buffer | undefined = undefined; if (flags.ed) { - const firstDecoded = decodeCborFirst(intBuffer); + const firstDecoded = decodeCborFirst(authData); const firstEncoded = Buffer.from(cbor.encode(firstDecoded) as ArrayBuffer); extensionsDataBuffer = firstEncoded; - intBuffer = intBuffer.slice(firstEncoded.byteLength); + authData = authData.slice((pointer += firstEncoded.byteLength)); } - if (intBuffer.byteLength > 0) { + if (authData.byteLength > pointer) { throw new Error('Leftover bytes detected while parsing authenticator data'); } |