# Why SignDoc only has one AccountNumber but AuthInfo has multiple SignerInfo?

**URL:** <https://forum.cosmos.network/t/why-signdoc-only-has-one-accountnumber-but-authinfo-has-multiple-signerinfo/4079>\
**Category:** Cosmos-SDK\
**Created:** [October 27, 2020, 9:41am UTC](https://forum.cosmos.network/t/why-signdoc-only-has-one-accountnumber-but-authinfo-has-multiple-signerinfo/4079 "2020-10-27T09:41:19Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![calvinlauco](https://avatars.discourse-cdn.com/v4/letter/c/a8b319/32.png) [@calvinlauco](https://forum.cosmos.network/u/calvinlauco)\
**Post date:** [October 27, 2020, 9:41am UTC](https://forum.cosmos.network/t/why-signdoc-only-has-one-accountnumber-but-authinfo-has-multiple-signerinfo/4079/1 "2020-10-27T09:41:19Z")

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I am studying the ADR20 ([https://github.com/cosmos/cosmos-sdk/blob/master/docs/architecture/adr-020-protobuf-transaction-encoding.md](https://github.com/cosmos/cosmos-sdk/blob/master/docs/architecture/adr-020-protobuf-transaction-encoding.md)) and roughly understand the encoding and signing basics.

I notice there can be multiple `SignerInfo` under `AuthInfo`, each I assume correspond to either 1) the required signer of each message or 2) the required signers if it’s a multisig address? However, in the `SignDoc` structure, only one `AccountNumber` is defined. Does it mean for the same transaction each signer will have a different `SignDoc` and they have to sign with their `AccountNumber`?

Thank you.

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**Author:** ![ebuchman](https://yyz1.discourse-cdn.com/flex031/user_avatar/forum.cosmos.network/ebuchman/32/6645_2.png) [@ebuchman](https://forum.cosmos.network/u/ebuchman)\
**Post date:** [November 20, 2020, 8:17pm UTC](https://forum.cosmos.network/t/why-signdoc-only-has-one-accountnumber-but-authinfo-has-multiple-signerinfo/4079/2 "2020-11-20T20:17:50Z")

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> I notice there can be multiple `SignerInfo` under `AuthInfo` , each I assume correspond to either 1) the required signer of each message or 2) the required signers if it’s a multisig address?

It’s just (1), since for (2) there is logically only 1 account, and the multi signatures are gathered and concatenated and submitted as a single signer.

> Does it mean for the same transaction each signer will have a different `SignDoc` and they have to sign with their `AccountNumber` ?

Yes. Note under `Signature verifiers do:`

```auto
For each required signer:
- Pull account number and sequence from the state.
- Obtain the public key either from state or AuthInfo's signer_infos.
- Create a SignDoc and serialize it using ADR 027.

```