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Make finalization part of the stream

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Fedor Indutny 2024-07-19 19:17:02 -07:00 • committed by GitHub
parent c93a211595
commit 86b4da1ec2
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3 changed files with 122 additions and 55 deletions
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115
ts/AttachmentCrypto.ts
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@ -21,6 +21,7 @@ import { createName, getRelativePath } from './util/attachmentPath';
import { appendPaddingStream, logPadSize } from './util/logPadding';
import { prependStream } from './util/prependStream';
import { appendMacStream } from './util/appendMacStream';
import { finalStream } from './util/finalStream';
import { getIvAndDecipher } from './util/getIvAndDecipher';
import { getMacAndUpdateHmac } from './util/getMacAndUpdateHmac';
import { trimPadding } from './util/trimPadding';
@ -378,6 +379,65 @@ export async function decryptAttachmentV2ToSink(
}),
trimPadding(options.size),
peekAndUpdateHash(plaintextHash),
finalStream(() => {
const ourMac = hmac.digest();
const ourDigest = digest.digest();
strictAssert(
ourMac.byteLength === ATTACHMENT_MAC_LENGTH,
`${logId}: Failed to generate ourMac!`
);
strictAssert(
theirMac != null && theirMac.byteLength === ATTACHMENT_MAC_LENGTH,
`${logId}: Failed to find theirMac!`
);
strictAssert(
ourDigest.byteLength === DIGEST_LENGTH,
`${logId}: Failed to generate ourDigest!`
);
if (!constantTimeEqual(ourMac, theirMac)) {
throw new Error(`${logId}: Bad MAC`);
}
const { type } = options;
switch (type) {
case 'local':
case 'backupThumbnail':
log.info(
`${logId}: skipping digest check since this is a ${type} attachment`
);
break;
case 'standard':
if (!constantTimeEqual(ourDigest, options.theirDigest)) {
throw new Error(`${logId}: Bad digest`);
}
break;
default:
throw missingCaseError(type);
}
if (!outerEncryption) {
return;
}
strictAssert(outerHmac, 'outerHmac must exist');
const ourOuterMac = outerHmac.digest();
strictAssert(
ourOuterMac.byteLength === ATTACHMENT_MAC_LENGTH,
`${logId}: Failed to generate ourOuterMac!`
);
strictAssert(
theirOuterMac != null &&
theirOuterMac.byteLength === ATTACHMENT_MAC_LENGTH,
`${logId}: Failed to find theirOuterMac!`
);
if (!constantTimeEqual(ourOuterMac, theirOuterMac)) {
throw new Error(`${logId}: Bad outer encryption MAC`);
}
}),
sink,
].filter(isNotNil)
);
@ -397,72 +457,17 @@ export async function decryptAttachmentV2ToSink(
await readFd?.close();
}
const ourMac = hmac.digest();
const ourDigest = digest.digest();
const ourPlaintextHash = plaintextHash.digest('hex');
strictAssert(
ourMac.byteLength === ATTACHMENT_MAC_LENGTH,
`${logId}: Failed to generate ourMac!`
);
strictAssert(
theirMac != null && theirMac.byteLength === ATTACHMENT_MAC_LENGTH,
`${logId}: Failed to find theirMac!`
);
strictAssert(
ourDigest.byteLength === DIGEST_LENGTH,
`${logId}: Failed to generate ourDigest!`
);
strictAssert(
ourPlaintextHash.length === HEX_DIGEST_LENGTH,
`${logId}: Failed to generate file hash!`
);
if (!constantTimeEqual(ourMac, theirMac)) {
throw new Error(`${logId}: Bad MAC`);
}
const { type } = options;
switch (type) {
case 'local':
case 'backupThumbnail':
log.info(
`${logId}: skipping digest check since this is a ${type} attachment`
);
break;
case 'standard':
if (!constantTimeEqual(ourDigest, options.theirDigest)) {
throw new Error(`${logId}: Bad digest`);
}
break;
default:
throw missingCaseError(type);
}
strictAssert(
iv != null && iv.byteLength === IV_LENGTH,
`${logId}: failed to find their iv`
);
if (outerEncryption) {
strictAssert(outerHmac, 'outerHmac must exist');
const ourOuterMac = outerHmac.digest();
strictAssert(
ourOuterMac.byteLength === ATTACHMENT_MAC_LENGTH,
`${logId}: Failed to generate ourOuterMac!`
);
strictAssert(
theirOuterMac != null &&
theirOuterMac.byteLength === ATTACHMENT_MAC_LENGTH,
`${logId}: Failed to find theirOuterMac!`
);
if (!constantTimeEqual(ourOuterMac, theirOuterMac)) {
throw new Error(`${logId}: Bad outer encryption MAC`);
}
}
return {
iv,
plaintextHash: ourPlaintextHash,