1sealsemantic last-mile verification

Research / Finding

Non-Constant-Time Message Key Comparison in Secret Chat Decryption Violates Security Guidelines

F-TELEGRAM-E2E-001

Public snapshot: 26 Sep 2026. Status, releases and attribution belong to each source below; none is inferred from another record.

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Recorded evidence

—score not recorded
TelegramMessenger/Telegram-iOSReported fixTelegramMessenger/Telegram-iOS

Non-Constant-Time Message Key Comparison in Secret Chat Decryption Violates Security Guidelines

fixed publicly
details
Finding IDs
F-TELEGRAM-E2E-001
Status
fixed publicly
Reported via
Telegram security contact
Note
accepted as LOW. public fix commit 9d33962c013e68dcecd8c26bb23ca232bc52c2a2 on 2026-02-13 replaces direct message-key comparison with constTimeIsEqual; the fix is present in release-12.5.

F-TELEGRAM-E2E-001: Secret handling. Message-key comparison is not constant-time. Reviewed 24 Sep 2026. Mechanism assessed by 1seal.

Mechanism source for F-TELEGRAM-E2E-001

Security area (1seal assessment): Confidentiality. Message-key comparison is not constant-time. Reviewed 24 Sep 2026.

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