> For the complete documentation index, see [llms.txt](https://blockgram.gitbook.io/blockgram-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://blockgram.gitbook.io/blockgram-docs/about-blockgram/core-features/share-encrypted-files-with-blockchain-proof.md).

# Share Encrypted Files with Blockchain Proof

BlockGram allows users to share sensitive files, media, and documents directly in Telegram chats with end-to-end encryption, while anchoring cryptographic proofs on-chain. This approach combines privacy, decentralization, and verifiability into a seamless file-sharing experience.

#### Secure and Seamless File Sharing

Traditional messaging apps offer limited security and verifiability for file sharing. BlockGram solves these challenges by providing:

* Fully encrypted, peer-to-peer file transfers
* On-chain anchoring of file metadata and hash signatures
* Verifiable proof of authorship, timestamp, and authenticity
* Optional permanent storage on decentralized networks

All of this happens directly in Telegram without requiring extra apps, wallets, or complex setups.

#### File Encryption and Access Control

**Encryption Workflow**

* Files are encrypted on the client device using AES-256 symmetric encryption
* A unique key is generated per file and wrapped with the recipient’s public key using RSA or elliptic curve encryption
* File chunks are transmitted via Telegram servers or optionally stored on decentralized networks like IPFS, Arweave, or Filecoin
* Recipients decrypt files locally using their private key

**Access Control**

* Only the intended recipient can access the file
* Optional expiration or revocation rights can be enforced via smart contracts

**Storage Options**

* Temporary in-chat delivery with encrypted payloads
* Long-term decentralized storage with on-chain hash anchoring

#### Blockchain-Verified Integrity

Every file shared generates a cryptographic hash that is recorded on-chain. This creates a decentralized certificate of authenticity, ensuring the file has not been tampered with and can be independently verified.

#### Advanced Use Cases

* **Legal Documents:** Contracts and agreements can be shared with immutable timestamping and verified recipients
* **Enterprise Workflows:** Encrypted reports with proof of delivery for compliance audits
* **NFT-Backed Media:** Restrict file access to NFT holders, proving ownership or usage rights
* **Time-Locked Sharing:** Smart contracts delay access or enforce download conditions

#### Technical Stack

* Client-side AES-256 encryption for files
* RSA or ECC encryption for key wrapping
* Decentralized storage via IPFS, Arweave, Filecoin
* On-chain hash anchoring for integrity verification
* Optional zk-SNARKs for future zero-knowledge access control

#### Security and Privacy Features

* End-to-end encryption ensures no intermediary can read files
* On-chain hash anchors detect tampering or replay attacks
* Metadata remains private, even with centralized storage
* Planned zero-knowledge proofs will allow verification without revealing file content or user identity

#### Benefits

* Eliminates dependence on cloud drives or third-party sharing tools
* Guarantees verifiable authenticity and authorship
* Preserves privacy while enabling trustless, auditable exchanges
* Enhances Telegram’s file-sharing with blockchain-level securityza