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fix: support 3DES S/MIME decryption by importing legacy RSAES-PKCS1-v1_5 keys #35

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This commit is contained in:
Linus Rath
2026-03-30 16:00:27 +02:00
parent 789d211a71
commit 8937777bcd
5 changed files with 107 additions and 15 deletions
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components/email/email-viewer.tsx
+3 -1
View File
@@ -1545,7 +1545,7 @@ export function EmailViewer({
if (detection.type === 'enveloped-data') {
// Encrypted message
const { keyRecords, unlockedDecryptionKeys } = smimeStore;
const { keyRecords, unlockedDecryptionKeys, unlockedLegacyDecryptionKeys } = smimeStore;
smimeDebug('[S/MIME] decrypt attempt:', { keyRecordCount: keyRecords.length, unlockedKeyCount: unlockedDecryptionKeys.size, keyRecordIds: keyRecords.map(k => k.id) });
// Short-circuit: no keys imported at all
@@ -1569,6 +1569,7 @@ export function EmailViewer({
cmsBytes: candidate.normalized,
keyRecords,
unlockedKeys: unlockedDecryptionKeys,
legacyUnlockedKeys: unlockedLegacyDecryptionKeys,
});
smimeDebug('[S/MIME] decrypt success with candidate:', {
source: candidate.source,
@@ -1804,6 +1805,7 @@ export function EmailViewer({
smimeStore.autoImportSignerCerts,
smimeStore.keyRecords,
smimeStore.unlockedDecryptionKeys,
smimeStore.unlockedLegacyDecryptionKeys,
smimeStore,
]);
lib/smime/crypto-engine.ts
+6
View File
@@ -274,6 +274,12 @@ export function getLinerCryptoEngine(): pkijs.CryptoEngine {
return linerEngine!;
}
/** Get the webcrypto-liner Crypto instance (for importKey with legacy algorithms). */
export function getLinerCrypto(): Crypto {
ensureLiner();
return linerCryptoInstance!;
}
/**
* Run an async operation with the global PKI.js engine set to webcrypto-liner,
* then restore the previous engine afterwards.
lib/smime/pkcs12-import.ts
+38 -3
View File
@@ -5,7 +5,7 @@ import {
classifyCapabilities,
} from './certificate-utils';
import type { SmimeKeyRecord, Pkcs12ImportResult } from './types';
import { withLinerEngine } from './crypto-engine';
import { withLinerEngine, getLinerCrypto } from './crypto-engine';
const KDF_ITERATIONS = 600_000;
const AES_KEY_LENGTH = 256;
@@ -217,6 +217,8 @@ async function encryptPrivateKey(
export interface UnlockedKeyPair {
signingKey: CryptoKey;
decryptionKey?: CryptoKey;
/** Key imported via webcrypto-liner as RSAES-PKCS1-v1_5 for legacy S/MIME (3DES) messages */
legacyDecryptionKey?: CryptoKey;
}
/** Decrypt stored PKCS#8 bytes and import as non-extractable CryptoKeys for signing and decryption. */
@@ -257,7 +259,22 @@ export async function unlockPrivateKey(
} catch {
// Key may only support decryption (key-encipherment-only cert)
const decryptionKey = await crypto.subtle.importKey('pkcs8', pkcs8Bytes, decryptAlg, false, decryptUsages);
return { signingKey: decryptionKey, decryptionKey };
let legacyDecryptionKey: CryptoKey | undefined;
if (!isEcdsa) {
try {
const linerCrypto = getLinerCrypto();
legacyDecryptionKey = await linerCrypto.subtle.importKey(
'pkcs8',
pkcs8Bytes,
{ name: 'RSAES-PKCS1-v1_5' },
false,
['decrypt'],
);
} catch {
// webcrypto-liner may not be available
}
}
return { signingKey: decryptionKey, decryptionKey, legacyDecryptionKey };
}
// Also import for decryption (separate CryptoKey handle required by Web Crypto)
@@ -268,7 +285,25 @@ export async function unlockPrivateKey(
// Key may only support signing (digitalSignature-only cert)
}
return { signingKey, decryptionKey };
// Import a legacy decryption key via webcrypto-liner for RSAES-PKCS1-v1_5 key transport
// (used by older S/MIME messages encrypted with 3DES, RC2, etc.)
let legacyDecryptionKey: CryptoKey | undefined;
if (!isEcdsa) {
try {
const linerCrypto = getLinerCrypto();
legacyDecryptionKey = await linerCrypto.subtle.importKey(
'pkcs8',
pkcs8Bytes,
{ name: 'RSAES-PKCS1-v1_5' },
false,
['decrypt'],
);
} catch {
// webcrypto-liner may not be available or key format unsupported
}
}
return { signingKey, decryptionKey, legacyDecryptionKey };
}
/** Get decrypted PKCS#8 bytes (for export flow). */
lib/smime/smime-decrypt.ts
+33 -5
View File
@@ -15,8 +15,10 @@ export interface DecryptionInput {
cmsBytes: ArrayBuffer;
/** All imported key records to try matching against */
keyRecords: SmimeKeyRecord[];
/** Unlocked CryptoKey map: keyRecordId → CryptoKey */
/** Unlocked CryptoKey map: keyRecordId → CryptoKey (RSA-OAEP) */
unlockedKeys: Map<string, CryptoKey>;
/** Unlocked legacy CryptoKey map: keyRecordId → CryptoKey (RSAES-PKCS1-v1_5 via webcrypto-liner) */
legacyUnlockedKeys?: Map<string, CryptoKey>;
}
export interface DecryptionResult {
@@ -34,7 +36,7 @@ export interface DecryptionResult {
* @throws Error if no matching key is found, key is locked, or decryption fails
*/
export async function smimeDecrypt(input: DecryptionInput): Promise<DecryptionResult> {
const { cmsBytes, keyRecords, unlockedKeys } = input;
const { cmsBytes, keyRecords, unlockedKeys, legacyUnlockedKeys } = input;
// Parse the CMS ContentInfo wrapper
const contentInfo = parseContentInfo(cmsBytes);
@@ -51,6 +53,19 @@ export async function smimeDecrypt(input: DecryptionInput): Promise<DecryptionRe
for (const { keyRecord, recipientIndex } of matchedRecords) {
const privateKey = unlockedKeys.get(keyRecord.id);
if (!privateKey) {
// Try legacy key (RSAES-PKCS1-v1_5) if no RSA-OAEP key
const legacyKey = legacyUnlockedKeys?.get(keyRecord.id);
if (legacyKey) {
try {
const decrypted = await decryptWithKey(envelopedData, recipientIndex, legacyKey, keyRecord);
return {
mimeBytes: new Uint8Array(decrypted),
keyRecordId: keyRecord.id,
};
} catch {
continue;
}
}
continue; // Key exists but isn't unlocked — skip, caller should unlock first
}
@@ -61,15 +76,28 @@ export async function smimeDecrypt(input: DecryptionInput): Promise<DecryptionRe
keyRecordId: keyRecord.id,
};
} catch {
// This key didn't work, try the next one
// RSA-OAEP key didn't work, try legacy RSAES-PKCS1-v1_5 key
const legacyKey = legacyUnlockedKeys?.get(keyRecord.id);
if (legacyKey) {
try {
const decrypted = await decryptWithKey(envelopedData, recipientIndex, legacyKey, keyRecord);
return {
mimeBytes: new Uint8Array(decrypted),
keyRecordId: keyRecord.id,
};
} catch {
// Legacy key also didn't work, try the next record
}
}
continue;
}
}
// Check if we had matching records but none were unlocked
const hasLockedMatch = matchedRecords.some(m => !unlockedKeys.has(m.keyRecord.id));
const isUnlocked = (id: string) => unlockedKeys.has(id) || (legacyUnlockedKeys?.has(id) ?? false);
const hasLockedMatch = matchedRecords.some(m => !isUnlocked(m.keyRecord.id));
if (hasLockedMatch) {
const lockedRecord = matchedRecords.find(m => !unlockedKeys.has(m.keyRecord.id))!;
const lockedRecord = matchedRecords.find(m => !isUnlocked(m.keyRecord.id))!;
throw new SmimeKeyLockedError(
'S/MIME key is locked. Unlock it to decrypt this message.',
lockedRecord.keyRecord.id,
stores/smime-store.ts
+27 -6
View File
@@ -91,10 +91,12 @@ function clearRememberedUnlocks(): void {
async function restoreRememberedKeys(keyRecords: SmimeKeyRecord[]): Promise<{
unlockedKeys: Map<string, CryptoKey>;
unlockedDecryptionKeys: Map<string, CryptoKey>;
unlockedLegacyDecryptionKeys: Map<string, CryptoKey>;
}> {
const rememberedUnlocks = readRememberedUnlocks();
const unlockedKeys = new Map<string, CryptoKey>();
const unlockedDecryptionKeys = new Map<string, CryptoKey>();
const unlockedLegacyDecryptionKeys = new Map<string, CryptoKey>();
let removedStaleEntries = false;
for (const record of keyRecords) {
@@ -104,11 +106,14 @@ async function restoreRememberedKeys(keyRecords: SmimeKeyRecord[]): Promise<{
}
try {
const { signingKey, decryptionKey } = await unlockPrivateKey(record, passphrase);
const { signingKey, decryptionKey, legacyDecryptionKey } = await unlockPrivateKey(record, passphrase);
unlockedKeys.set(record.id, signingKey);
if (decryptionKey) {
unlockedDecryptionKeys.set(record.id, decryptionKey);
}
if (legacyDecryptionKey) {
unlockedLegacyDecryptionKeys.set(record.id, legacyDecryptionKey);
}
} catch {
delete rememberedUnlocks[record.id];
removedStaleEntries = true;
@@ -119,7 +124,7 @@ async function restoreRememberedKeys(keyRecords: SmimeKeyRecord[]): Promise<{
writeRememberedUnlocks(rememberedUnlocks);
}
return { unlockedKeys, unlockedDecryptionKeys };
return { unlockedKeys, unlockedDecryptionKeys, unlockedLegacyDecryptionKeys };
}
interface SmimePersistedState {
@@ -146,6 +151,7 @@ interface SmimeStore extends SmimePersistedState {
// Runtime only — never persisted
unlockedKeys: Map<string, CryptoKey>;
unlockedDecryptionKeys: Map<string, CryptoKey>;
unlockedLegacyDecryptionKeys: Map<string, CryptoKey>;
isLoading: boolean;
error: string | null;
@@ -189,6 +195,7 @@ export const useSmimeStore = create<SmimeStore>()(
publicCerts: [],
unlockedKeys: new Map(),
unlockedDecryptionKeys: new Map(),
unlockedLegacyDecryptionKeys: new Map(),
isLoading: false,
error: null,
@@ -231,6 +238,10 @@ export const useSmimeStore = create<SmimeStore>()(
...state.unlockedDecryptionKeys,
...restoredKeys.unlockedDecryptionKeys,
]),
unlockedLegacyDecryptionKeys: new Map([
...state.unlockedLegacyDecryptionKeys,
...restoredKeys.unlockedLegacyDecryptionKeys,
]),
isLoading: false,
}));
return;
@@ -332,6 +343,8 @@ export const useSmimeStore = create<SmimeStore>()(
unlockedKeys.delete(id);
const unlockedDecryptionKeys = new Map(state.unlockedDecryptionKeys);
unlockedDecryptionKeys.delete(id);
const unlockedLegacyDecryptionKeys = new Map(state.unlockedLegacyDecryptionKeys);
unlockedLegacyDecryptionKeys.delete(id);
// Remove any identity bindings pointing to this key
const bindings = { ...state.identityKeyBindings };
for (const [identityId, keyId] of Object.entries(bindings)) {
@@ -346,6 +359,7 @@ export const useSmimeStore = create<SmimeStore>()(
keyRecords: state.keyRecords.filter((k) => k.id !== id),
unlockedKeys,
unlockedDecryptionKeys,
unlockedLegacyDecryptionKeys,
identityKeyBindings: bindings,
accountPreferences,
};
@@ -363,7 +377,7 @@ export const useSmimeStore = create<SmimeStore>()(
const record = get().keyRecords.find((k) => k.id === id);
if (!record) throw new Error('Key record not found');
const { signingKey, decryptionKey } = await unlockPrivateKey(record, passphrase);
const { signingKey, decryptionKey, legacyDecryptionKey } = await unlockPrivateKey(record, passphrase);
if (get().rememberUnlockedKeys) {
rememberUnlockedKey(id, passphrase);
}
@@ -374,7 +388,11 @@ export const useSmimeStore = create<SmimeStore>()(
if (decryptionKey) {
unlockedDecryptionKeys.set(id, decryptionKey);
}
return { unlockedKeys, unlockedDecryptionKeys };
const unlockedLegacyDecryptionKeys = new Map(state.unlockedLegacyDecryptionKeys);
if (legacyDecryptionKey) {
unlockedLegacyDecryptionKeys.set(id, legacyDecryptionKey);
}
return { unlockedKeys, unlockedDecryptionKeys, unlockedLegacyDecryptionKeys };
});
},
@@ -385,13 +403,15 @@ export const useSmimeStore = create<SmimeStore>()(
unlockedKeys.delete(id);
const unlockedDecryptionKeys = new Map(state.unlockedDecryptionKeys);
unlockedDecryptionKeys.delete(id);
return { unlockedKeys, unlockedDecryptionKeys };
const unlockedLegacyDecryptionKeys = new Map(state.unlockedLegacyDecryptionKeys);
unlockedLegacyDecryptionKeys.delete(id);
return { unlockedKeys, unlockedDecryptionKeys, unlockedLegacyDecryptionKeys };
});
},
lockAllKeys: () => {
clearRememberedUnlocks();
set({ unlockedKeys: new Map(), unlockedDecryptionKeys: new Map() });
set({ unlockedKeys: new Map(), unlockedDecryptionKeys: new Map(), unlockedLegacyDecryptionKeys: new Map() });
},
getKeyRecordForIdentity: (identityId) => {
@@ -476,6 +496,7 @@ export const useSmimeStore = create<SmimeStore>()(
publicCerts: [],
unlockedKeys: new Map(),
unlockedDecryptionKeys: new Map(),
unlockedLegacyDecryptionKeys: new Map(),
identityKeyBindings: {},
defaultSignIdentity: {},
defaultEncrypt: false,