How does Snapchat’s My Eyes Only encryption technically work — client‑side key generation and storage?
Executive summary
Snapchat’s “My Eyes Only” (MEO) locks selected Memories with client‑side encryption so that the plaintext is not available to Snapchat; the encryption key is derived from a user‑chosen passcode via a key‑derivation step and the service provides no recovery that preserves existing content if the passcode is lost [1] [2]. Public reporting and community reverse‑engineering indicate the encrypted blob for MEO is a locally encrypted symmetric payload (commonly implemented with AES‑like ciphers) whose decryption depends entirely on the locally derived key, while the passcode or key material is not stored in a recoverable form on Snapchat servers [3] [4] [1].
1. What “client‑side encryption” means for MEO
Client‑side encryption here means snaps moved into MEO are encrypted on the user’s device before upload or storage, so Snapchat’s backend does not hold the unencrypted media and cannot decrypt it without the user’s passcode‑derived key; Snapchat’s documentation and support messaging assert that without the password the company cannot view MEO content and that forgetting the passcode destroys access [2] [1].
2. How the key is derived from the passcode (KDF role and guesses in reporting)
Multiple explainer pieces and help guides state that the MEO encryption key is produced by deriving a stronger cryptographic key from the user’s passcode using a key‑derivation function (KDF) — reporting suggests PBKDF2 or a modern alternative such as Argon2 is likely used to resist brute‑force and dictionary attacks, though Snapchat does not publicly publish the exact KDF parameters [3] [1]. Those sources emphasize that the security model depends heavily on passcode strength because the passcode is the input to the KDF that ultimately protects the symmetric key [4] [1].
3. Symmetric encryption algorithm and what reporting infers
Guides and community reporting repeatedly say MEO uses a symmetric encryption cipher — commonly AES or an AES‑256 equivalent — to encrypt media blobs, but Snapchat hasn’t publicly confirmed the exact algorithm; therefore analyses refer to AES as the likely cipher family for bulk encryption while noting the platform’s public silence on specifics [3] [4].
4. Where the passcode and key material live (storage and hashing)
Reverse‑engineering efforts and community tools indicate Snapchat does not store the plain passcode; instead, device‑side artifacts show the app keeps only hashed/derived values. Multiple GitHub projects report that the 4‑digit MEO PIN is stored in the app database encrypted or hashed with bcrypt on Android devices at /data/data/com.snapchat.android/databases/memories.db, a finding from independent researchers [5] [6]. Snapchat’s own messaging aligns with the idea that the company does not retain a recoverable passcode or key [2].
5. Practical attack and recovery opportunities observed by forensic analysts
Forensics vendors and forum posts note caveats: if snaps were previously viewed or remain in device caches, local copies or cached decrypted versions can sometimes be recovered and decrypted by forensic tools (GrayKey and Axiom are mentioned by practitioners), meaning MEO’s protection is strongest for untouched encrypted blobs but weaker where local plaintext or cached data exists [7]. Community tools also attempt brute‑force workflows on rooted devices, and GitHub projects describe automating PIN guessing against local app files — realities that demonstrate attackers with device access and rooting capabilities can sometimes bypass protections, though Snapchat has rate‑limit and lockout behaviors that complicate automated guessing [5] [6] [8].
6. Tradeoffs, limitations and unanswered technical specifics
The public record describes a clear security model—client‑side KDF → symmetric encryption → no server‑side passcode copy—but leaves important engineering details unverified: exact KDF algorithm and parameters, cipher mode and key management practices, salting conventions, or how biometric unlock interacts with the derived key are not confirmed by Snapchat in the cited sources [3] [1]. Reporting therefore provides a defensible high‑level picture while acknowledging that definitive cryptographic confirmation would require Snapchat’s technical disclosure or independent code/audit access not present in the referenced material [3] [1] [2].