Data Recovery Case File · Solid State & Flash · Tied to the Handset

Videos That Will Not Play After Decryption

This enquiry described a sequence that sounds unremarkable and contains one detail that governs everything. A new SD card was installed into an Android phone and all the videos transferred onto it: "once complete, we found that the videos will no longer play. The card was encrypted to the phone, but has since been decrypted." That middle clause is the whole case. Android offers to take a card over completely — encrypting it and binding it to the handset — and when it does, the card stops being a card in any portable sense. Understanding which state it was in, and what "since been decrypted" actually involved, decides whether this is straightforward or genuinely difficult.

The decode: what adopting a card does, and where the key lives

The two ways a phone can use a card: as portable storage, where it is formatted normally and can be pulled out and read anywhere — the arrangement most people assume. Or as adopted storage, where the handset formats it, encrypts it, and treats it as an extension of its own internal storage. Adopted cards are bound to that specific device: the encryption key is held by the phone, not written on the card in usable form. Pull an adopted card out and put it in a computer and it appears as an unrecognised or empty volume, because there is nothing there anybody else can read.

Why the transfer completing is misleading: the videos were copied successfully onto an encrypted volume the phone could read perfectly at the time. Nothing was wrong at that moment. The problem appears later, once something changes about the key relationship — which is exactly what her next clause describes.

What "since been decrypted" might mean, and why it matters enormously: two very different things. If the phone migrated the card back to portable storage — a supported operation that decrypts the contents and rewrites them unencrypted — then the data should be readable and the fault is something else, likely an interruption partway through that migration. But if the card was instead reformatted, or the phone was reset, or the card was simply removed and the encryption relationship abandoned, then the key may no longer exist. On adopted storage the key lives with the handset; reset the handset and the key is gone, and the encrypted contents become permanently unreadable. Establishing which happened is the first job and it costs nothing.

Why the original handset is the most important object in this case: more important than the card. If it still exists, still works, and has not been reset since, it holds the key and remains the route in — the card can be reinserted and the contents read or migrated properly. Anyone in this position should stop and preserve that phone before doing anything else.

What must not happen: the card must not be formatted, and no computer's offer to initialise it should be accepted. And nothing further should be attempted on the phone — particularly not a reset — until the key position is settled.

On the bench

The card was imaged write-blocked before anything else, so that whatever state it was in was preserved while the questions were answered. The encryption state was then established on the image — whether the volume was still encrypted, partially migrated, or genuinely rewritten in the clear — since that single finding decides the route and the honest odds. The originating handset was identified as the key holder and its status established before any decryption was contemplated, and decryption ran strictly against the lawfully-held key on the owner's own device.

The outcome

The card imaged before further action, the encryption state established and the key position settled before anything was proposed. Free assessment, one fixed written figure including VAT; where a chip has to be removed, 50% of parts and labour is payable upfront with the balance only on success — otherwise no recovery, no fee. The decode, for anyone whose card was encrypted to a phone: Android can adopt a card as an extension of internal storage, encrypting it and binding it to that handset with the key held by the phone rather than the card — so an adopted card is unreadable anywhere else by design; whether your content survives depends on what "decrypted" involved, since a proper migration rewrites it in the clear while a reset or reformat destroys the key permanently; the originating handset is the most important object you have, so preserve it and do not reset it.

Our case files are drawn from genuine enquiries received by our laboratory over the past ten years, anonymised to protect client confidentiality. Each one describes the diagnostic and recovery procedure our engineers apply to that fault, using the equipment listed.