— Cryptographically secure memos for every Nano block

5 min readApr 18, 2021


Announcing a new website and service from SomeNano … NanoMemo!

What is NanoMemo?

Let’s start by answering, what is Nano? Nano is a secure/decentralized, fast, and feeless cryptocurrency. It is digital cash in, arguably, its most efficient form. Nano prides itself in doing one thing and one thing well, fast/feeless/secure peer-to-peer transfer of value. In order to do value transfer well, the Nano protocol must be extremely efficient. This means that the data contained in a Nano Block is kept minimal.

And to that point, a freetext memo field (a descriptor of why the Block was created) does not exist.

NanoMemo looks to fill people/service’s desire for a freetext memo field attached to a Nano Block. NanoMemo allows anyone that creates a Nano Block (makes a transaction with Nano) to write a memo and digitally sign it so that anyone can prove that the entity that created the Nano Block also wrote the memo. Additionally, NanoMemo offers a private memo option that encrypts a memo so that only a specified Nano Account can decrypt and read the memo’s message.

Recent memos from

How do I read a memo?

To read a memo for a specific Nano Block, all you need to know is the Nano Block’s hash. This is a unique identifier for each Nano Block on the Nano Network. Once you have the hash, simply enter it into the search box at the top of and hit enter.

If a memo has been written for that block, you will see the message. If the memo has been encrypted, you will see ciphertext and have the option to enter your private key to decrypt the message if you were the intended recipient.

If no memo has been written, you will only see the details of the Nano Block. If the Nano Block is yours, there will be a link to write and save a memo for that Nano Block.

Example Memos


If you are a developer, you can request memos through the API. Three options:

How do I write a memo?

Screenshot of the form to write a memo

To write a memo, you must have the private key for the Nano Block with which you want to associate your memo. This ensures the authenticity of a memo is inline with its corresponding Nano Block.

On this website you can go to Write Memo to manually write a memo. On that page you will also be given the option to encrypt the memo and set what Nano Account will be able to decrypt and read the memo.


If you are a developer, you can write memos through the API. Two options:

How does NanoMemo work?

Memo Integrity — Digital Signature

NanoMemo uses the exact same digital signature algorithm that Nano Currency uses when signing Nano Blocks.

A digital signature is a mathematical scheme for verifying the authenticity of digital messages or documents. A valid digital signature, where the prerequisites are satisfied, gives a recipient very strong reason to believe that the message was created by a known sender (authentication), and that the message was not altered in transit (integrity). — thanks wikipedia.

In a NanoMemo, the hash of the corresponding Nano Block is appended to a written message and signed with a Nano Account’s private key. The signing Nano Account’s public key is derived from the private key, so the memo can verify it is being signed with the same private key that signed the Nano Block.

Once a NanoMemo is signed, anyone with the Nano Account’s public key can verify the memos integrity (to include authenticity). And the beauty of the Nano Network is that it acts as public key infrastructure. A Nano Account’s public key can be derived from its address (and vice versa).

Memo Confidentiality — Encrypted Message

NanoMemo uses public key encryption to encrypt messages and create an encrypted memo. Referencing the same public and private keys that are used in the signing of the memo, we convert the keys from a Ed25519 signing key pair into Curve25519 key pair suitable for Diffie-Hellman key exchange.

In this type of encryption, a recipient must be known. In NanoMemo, you must specify what Nano Address is the recipient of your encrtyped memo. It can be any Nano Account, even if they are not associated with the corresponding Nano Block.

Once a NanoMemo is encrypted, only someone or something in possession of the decrypting addresses private key will be able to decrypt the message.

And it is worth mentioning that an encrypted memo’s digital signature is calculated from the cipher text, not the decrypted plaintext.