> ## Documentation Index
> Fetch the complete documentation index at: https://hedera-0c6e0218-mintlify-enhance-scheduled-transaction-over.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Signature

<Info>
  This message is deprecated and succeeded by [SignaturePair](/hedera/sdks-and-apis/hedera-api/basic-types/signature-pair) and [SignatureMap ](/hedera/sdks-and-apis/hedera-api/basic-types/signaturemap)messages.
</Info>

A Signature corresponding to a Key. It is a sequence of bytes holding a public key signature from one of the three supported systems (ed25519, RSA-3072, ECDSA with p384). Or, it can be a list of signatures corresponding to a single threshold key. Or, it can be the ID of a smart contract instance, which is authorized to act as if it had a key. If an account has an ed25519 key associated with it, then the corresponding private key must sign any transaction to transfer cryptocurrency out of it. If it has a smart contract ID associated with it, then that smart contract is allowed to transfer cryptocurrency out of it. The smart contract doesn't actually have a key, and doesn't actually sign a transaction. But it's as if a virtual transaction were created, and the smart contract signed it with a private key. A key can also be a "threshold key", which means a list of M keys, any N of which must sign in order for the threshold signature to be considered valid. The keys within a threshold signature may themselves be threshold signatures, to allow complex signature requirements (this nesting is not supported in the currently, but will be supported in a future version of API). If a Signature message is missing the "signature" field, then this is considered to be a null signature. That is useful in cases such as threshold signatures, where some of the signatures can be null.

| Field | Type | Description | ​ |
| - | - | - | - |
| deprecated | ​ | ​ | ​ |
| signature | oneof | ​ | ​ |
| ​ | contract | ​ | Smart contract virtual signature (always length zero) |
| ​ | ed25519 | ​ | Ed25519 signature bytes |
| ​ | RSA\_3072 | ​ | RSA-3072 signature bytes |
| ​ | ECDSA\_384 | ​ | ECDSA p-384 signature bytes |
| ​ | thresholdSignature | ​[ThresholdSignature](/hedera/sdks-and-apis/hedera-api/basic-types/thresholdsignature)​ | A list of signatures for a single N-of-M threshold Key. This must be a list of exactly M signatures, at least N of which are non-null. |
| ​ | signatureList | ​[SignatureList](/hedera/sdks-and-apis/hedera-api/basic-types/signature-list)​ | A list of M signatures, each corresponding to a Key in a KeyList of the same length. |

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