Add caip122 namespace for SOL

NOTE: This PR is optimistic and refers to the to be URL for CAIP-122. If you want to read CAIP-122, it's currently under review at - https://github.com/ChainAgnostic/CAIPs/pull/122

namespace-identifier: solana-caip122 title: Solana Namespace - SIWx author: Haardik (@haardikk21) discussions-to: TBA status: Draft type: Standard created: 2022-07-06 updated: 2022-07-06 requires: ["CAIP-122", "CAIP-2", "CAIP-10"]

CAIP-122

For context, see the CAIP-122 specification.

Rationale

In Solana, signatures can only be made over raw bytes, Uint8Arrays in Javascript. This specification provides the signing algorithm to use, the type of the signing algorithm to identify it, and a method for signature creation and verification as required by CAIP-122.

Specification

Signing Algorithm

Solana uses the Ed25519 signing algorithm for signing and verifying messages. Solana keypairs are also just Ed25519 public/private keypairs.

Signature Type

We propose using the signature type solana:ed25519 to refer to the chain and algorithm used uniquely.

Signature Creation

The abstract data model must be converted into a string representation in an unambigious format, and then the string converted to a byte array to be signed over.

We propose the following string format, inspired from EIP-4361.

${domain} wants you to sign in with your Solana account:
${address}

${statement}

URI: ${uri}
Version: ${version}
Nonce: ${nonce}
Issued At: ${issued-at}
Expiration Time: ${expiration-time}
Not Before: ${not-before}
Request ID: ${request-id}
Chain ID: ${chain-id}
Resources:
- ${resources[0]}
- ${resources[1]}
...
- ${resources[n]}

For example,

service.org wants you to sign in with your Solana account:
GwAF45zjfyGzUbd3i3hXxzGeuchzEZXwpRYHZM5912F1

I accept the ServiceOrg Terms of Service: https://service.org/tos

URI: https://service.org/login
Version: 1
Nonce: 32891757
Issued At: 2021-09-30T16:25:24.000Z
Chain ID: 1
Resources:
- ipfs://Qme7ss3ARVgxv6rXqVPiikMJ8u2NLgmgszg13pYrDKEoiu
- https://example.com/my-web2-claim.json

which should then be converted into raw bytes (encoded as base64url for brevity).

c2VydmljZS5vcmcgd2FudHMgeW91IHRvIHNpZ24gaW4gd2l0aCB5b3VyIFNvbGFuYSBhY2NvdW50OgpHd0FGNDV6amZ5R3pVYmQzaTNoWHh6R2V1Y2h6RVpYd3BSWUhaTTU5MTJGMQoKSSBhY2NlcHQgdGhlIFNlcnZpY2VPcmcgVGVybXMgb2YgU2VydmljZTogaHR0cHM6Ly9zZXJ2aWNlLm9yZy90b3MKClVSSTogaHR0cHM6Ly9zZXJ2aWNlLm9yZy9sb2dpbgpWZXJzaW9uOiAxCk5vbmNlOiAzMjg5MTc1NwpJc3N1ZWQgQXQ6IDIwMjEtMDktMzBUMTY6MjU6MjQuMDAwWgpDaGFpbiBJRDogMQpSZXNvdXJjZXM6Ci0gaXBmczovL1FtZTdzczNBUlZneHY2clhxVlBpaWtNSjh1Mk5MZ21nc3pnMTNwWXJES0VvaXUKLSBodHRwczovL2V4YW1wbGUuY29tL215LXdlYjItY2xhaW0uanNvbg

Depending on the method used for signatures, this conversion may or may not happen automatically. For example, when using Phantom Wallet client-side, it performs the conversion automatically. However, if doing something server-side, you likely need to do this conversion yourself.

Signature Verification

Signature verification behaves similarly. We can use standard Ed25519 signature verification. We convert the input message to a bytes representation of the string format, then verify the signature over that. The verification public key should be the Solana wallet address, which is just a base58 encoded Ed25519 public key.

References

EIP-4361: Sign-In with Ethereum
CAIP-10: Account ID Specification
CAIP-2: Blockchain ID Specification
CAIP-122: Sign in With X Specification
Ed25519: Ed25519: high-speed high-security signatures

ChainAgnostic / namespaces